diff --git a/backend/trip/alembic/versions/26c89b7466f2_trip_multi_users.py b/backend/trip/alembic/versions/26c89b7466f2_trip_multi_users.py
new file mode 100644
index 0000000..3c6c825
--- /dev/null
+++ b/backend/trip/alembic/versions/26c89b7466f2_trip_multi_users.py
@@ -0,0 +1,91 @@
+"""Trip multi-users
+
+Revision ID: 26c89b7466f2
+Revises: 60a9bb641d8a
+Create Date: 2025-08-18 23:19:37.457354
+
+"""
+
+import sqlalchemy as sa
+import sqlmodel.sql.sqltypes
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "26c89b7466f2"
+down_revision = "60a9bb641d8a"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_table(
+        "tripmember",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("user", sqlmodel.sql.sqltypes.AutoString(), nullable=False),
+        sa.Column("invited_by", sqlmodel.sql.sqltypes.AutoString(), nullable=True),
+        sa.Column("invited_at", sa.DateTime(), nullable=False),
+        sa.Column("joined_at", sa.DateTime(), nullable=True),
+        sa.Column("trip_id", sa.Integer(), nullable=False),
+        sa.ForeignKeyConstraint(
+            ["invited_by"],
+            ["user.username"],
+            name=op.f("fk_tripmember_invited_by_user"),
+            ondelete="SET NULL",
+        ),
+        sa.ForeignKeyConstraint(
+            ["trip_id"], ["trip.id"], name=op.f("fk_tripmember_trip_id_trip"), ondelete="CASCADE"
+        ),
+        sa.ForeignKeyConstraint(
+            ["user"], ["user.username"], name=op.f("fk_tripmember_user_user"), ondelete="CASCADE"
+        ),
+        sa.PrimaryKeyConstraint("id", name=op.f("pk_tripmember")),
+    )
+    with op.batch_alter_table("tripchecklistitem", schema=None) as batch_op:
+        batch_op.drop_constraint(batch_op.f("fk_tripchecklistitem_user_user"), type_="foreignkey")
+        batch_op.drop_column("user")
+
+    with op.batch_alter_table("trippackinglistitem", schema=None) as batch_op:
+        batch_op.drop_constraint(batch_op.f("fk_trippackinglistitem_user_user"), type_="foreignkey")
+        batch_op.drop_column("user")
+
+    with op.batch_alter_table("tripitem", schema=None) as batch_op:
+        batch_op.drop_constraint(batch_op.f("fk_tripitem_day_id_tripday"), type_="foreignkey")
+
+    with op.batch_alter_table("tripday", schema=None) as batch_op:
+        batch_op.drop_constraint(batch_op.f("fk_tripday_user_user"), type_="foreignkey")
+        batch_op.drop_column("user")
+
+    with op.batch_alter_table("tripitem", schema=None) as batch_op:
+        batch_op.create_foreign_key(
+            batch_op.f("fk_tripitem_day_id_tripday"),
+            "tripday",
+            ["day_id"],
+            ["id"],
+            ondelete="CASCADE",
+        )
+
+
+def downgrade():
+    with op.batch_alter_table("trippackinglistitem", schema=None) as batch_op:
+        batch_op.add_column(sa.Column("user", sa.VARCHAR(), nullable=False))
+        batch_op.create_foreign_key(
+            batch_op.f("fk_trippackinglistitem_user_user"),
+            "user",
+            ["user"],
+            ["username"],
+            ondelete="CASCADE",
+        )
+
+    with op.batch_alter_table("tripday", schema=None) as batch_op:
+        batch_op.add_column(sa.Column("user", sa.VARCHAR(), nullable=False))
+        batch_op.create_foreign_key(
+            batch_op.f("fk_tripday_user_user"), "user", ["user"], ["username"], ondelete="CASCADE"
+        )
+
+    with op.batch_alter_table("tripchecklistitem", schema=None) as batch_op:
+        batch_op.add_column(sa.Column("user", sa.VARCHAR(), nullable=False))
+        batch_op.create_foreign_key(
+            batch_op.f("fk_tripchecklistitem_user_user"), "user", ["user"], ["username"], ondelete="CASCADE"
+        )
+
+    op.drop_table("tripmember")
diff --git a/backend/trip/models/models.py b/backend/trip/models/models.py
index 3ebdbb5..c09e420 100644
--- a/backend/trip/models/models.py
+++ b/backend/trip/models/models.py
@@ -261,6 +261,7 @@ class Trip(TripBase, table=True):
     shares: list["TripShare"] = Relationship(back_populates="trip", cascade_delete=True)
     packing_items: list["TripPackingListItem"] = Relationship(back_populates="trip", cascade_delete=True)
     checklist_items: list["TripChecklistItem"] = Relationship(back_populates="trip", cascade_delete=True)
+    memberships: list["TripMember"] = Relationship(back_populates="trip", cascade_delete=True)
 
 
 class TripCreate(TripBase):
@@ -279,6 +280,7 @@ class TripReadBase(TripBase):
     image: str | None
     image_id: int | None
     days: int
+    collaborators: list["TripMemberRead"]
 
     @classmethod
     def serialize(cls, obj: Trip) -> "TripRead":
@@ -289,6 +291,7 @@ class TripReadBase(TripBase):
             image=_prefix_assets_url(obj.image.filename) if obj.image else None,
             image_id=obj.image_id,
             days=len(obj.days),
+            collaborators=[TripMemberRead.serialize(m) for m in obj.memberships],
         )
 
 
@@ -298,6 +301,7 @@ class TripRead(TripBase):
     image_id: int | None
     days: list["TripDayRead"]
     places: list["PlaceRead"]
+    collaborators: list["TripMemberRead"]
 
     @classmethod
     def serialize(cls, obj: Trip) -> "TripRead":
@@ -309,17 +313,49 @@ class TripRead(TripBase):
             image_id=obj.image_id,
             days=[TripDayRead.serialize(day) for day in obj.days],
             places=[PlaceRead.serialize(place) for place in obj.places],
+            collaborators=[TripMemberRead.serialize(m) for m in obj.memberships],
         )
 
 
+class TripMember(SQLModel, table=True):
+    id: int | None = Field(default=None, primary_key=True)
+    user: str = Field(foreign_key="user.username", ondelete="CASCADE")
+    invited_by: str | None = Field(default=None, foreign_key="user.username", ondelete="SET NULL")
+    invited_at: datetime = Field(default_factory=lambda: datetime.now(UTC))
+    joined_at: datetime | None = None
+
+    trip_id: int = Field(foreign_key="trip.id", ondelete="CASCADE")
+    trip: Trip | None = Relationship(back_populates="memberships")
+
+
+class TripMemberCreate(BaseModel):
+    user: str
+
+
+class TripMemberRead(BaseModel):
+    user: str
+    invited_by: str | None = None
+    invited_at: datetime | None = None
+    joined_at: datetime | None = None
+
+    @classmethod
+    def serialize(cls, obj: TripMember) -> "TripMemberRead":
+        return cls(
+            user=obj.user, invited_by=obj.invited_by, invited_at=obj.invited_at, joined_at=obj.joined_at
+        )
+
+
+class TripInvitationRead(TripReadBase):
+    invited_by: str | None = None
+    invited_at: datetime
+
+
 class TripDayBase(SQLModel):
     label: str
 
 
 class TripDay(TripDayBase, table=True):
     id: int | None = Field(default=None, primary_key=True)
-    user: str = Field(foreign_key="user.username", ondelete="CASCADE")
-
     trip_id: int = Field(foreign_key="trip.id", ondelete="CASCADE")
     trip: Trip | None = Relationship(back_populates="days")
 
@@ -420,7 +456,6 @@ class TripPackingListItemBase(SQLModel):
 
 class TripPackingListItem(TripPackingListItemBase, table=True):
     id: int | None = Field(default=None, primary_key=True)
-    user: str = Field(foreign_key="user.username", ondelete="CASCADE")
 
     trip_id: int = Field(foreign_key="trip.id", ondelete="CASCADE")
     trip: Trip | None = Relationship(back_populates="packing_items")
diff --git a/backend/trip/routers/trips.py b/backend/trip/routers/trips.py
index afd7a7b..04d87a0 100644
--- a/backend/trip/routers/trips.py
+++ b/backend/trip/routers/trips.py
@@ -8,33 +8,120 @@ from ..deps import SessionDep, get_current_username
 from ..models.models import (Image, Place, Trip, TripChecklistItem,
                              TripChecklistItemCreate, TripChecklistItemRead,
                              TripChecklistItemUpdate, TripCreate, TripDay,
-                             TripDayBase, TripDayRead, TripItem,
-                             TripItemCreate, TripItemRead, TripItemUpdate,
-                             TripPackingListItem, TripPackingListItemCreate,
-                             TripPackingListItemRead, TripPackingListItemUpdate,
-                             TripRead, TripReadBase, TripShare,
-                             TripShareURL, TripUpdate)
-from ..security import verify_exists_and_owns
+                             TripDayBase, TripDayRead, TripInvitationRead,
+                             TripItem, TripItemCreate, TripItemRead,
+                             TripItemUpdate, TripMember, TripMemberCreate,
+                             TripMemberRead, TripPackingListItem,
+                             TripPackingListItemCreate,
+                             TripPackingListItemRead,
+                             TripPackingListItemUpdate, TripRead, TripReadBase,
+                             TripShare, TripShareURL, TripUpdate, User)
 from ..utils.utils import (b64img_decode, generate_urlsafe, remove_image,
-                           save_image_to_file)
+                           save_image_to_file, utc_now)
 
 router = APIRouter(prefix="/api/trips", tags=["trips"])
 
 
+def _get_trip_or_404(session, trip_id: int) -> Trip:
+    trip = session.get(Trip, trip_id)
+    if not trip:
+        raise HTTPException(status_code=404, detail="Not found")
+    return trip
+
+
+def _trip_from_token_or_404(session, token: str) -> TripShare:
+    share = session.exec(select(TripShare).where(TripShare.token == token)).first()
+    if not share:
+        raise HTTPException(status_code=404, detail="Not found")
+    return share
+
+
+def _trip_usernames(session, trip_id: int) -> set[str]:
+    owner = session.exec(select(Trip.user).where(Trip.id == trip_id)).first()
+    members = session.exec(select(TripMember.user).where(TripMember.trip_id == trip_id)).all()
+    return {owner} | set(members)
+
+
+def _can_access_trip(session, trip_id: int, username: str) -> bool:
+    # TODO: Optimize, if trip does not exist, trip_owner is none and we keep iterating on members despite trip not found
+    trip_owner = session.exec(select(Trip.user).where(Trip.id == trip_id)).first()
+    if trip_owner == username:
+        return True
+
+    is_member = session.exec(
+        select(TripMember.id)
+        .where(TripMember.trip_id == trip_id, TripMember.user == username, TripMember.joined_at.is_not(None))
+        .limit(1)
+    ).first()
+    return bool(is_member)
+
+
+def _verify_trip_member(session, trip_id: int, username: str) -> None:
+    if not _can_access_trip(session, trip_id, username):
+        raise HTTPException(status_code=404, detail="Not found")
+
+
 @router.get("", response_model=list[TripReadBase])
 def read_trips(
     session: SessionDep, current_user: Annotated[str, Depends(get_current_username)]
 ) -> list[TripReadBase]:
-    trips = session.exec(select(Trip).filter(Trip.user == current_user))
+    trips = session.exec(
+        select(Trip)
+        .join(TripMember, isouter=True)
+        .where(
+            (Trip.user == current_user)
+            | ((TripMember.user == current_user) & (TripMember.joined_at.is_not(None)))
+        )
+        .distinct()
+    )
     return [TripReadBase.serialize(trip) for trip in trips]
 
 
+@router.get("/invitations", response_model=list[TripInvitationRead])
+def read_pending_invitations(
+    session: SessionDep,
+    current_user: Annotated[str, Depends(get_current_username)],
+) -> list[TripInvitationRead]:
+    pending_inviattions = session.exec(
+        select(TripMember, Trip)
+        .join(Trip, Trip.id == TripMember.trip_id)
+        .where(
+            TripMember.user == current_user,
+            TripMember.joined_at.is_(None),
+        )
+    ).all()
+
+    invitations: list[TripInvitationRead] = []
+    for tm, trip in pending_inviattions:
+        base = TripReadBase.serialize(trip)
+        invitations.append(
+            TripInvitationRead(
+                **base.model_dump(),
+                invited_by=tm.invited_by,
+                invited_at=tm.invited_at,
+            )
+        )
+
+    return invitations
+
+
+@router.get("/invitations/pending", response_model=bool)
+def has_pending_invitations(
+    session: SessionDep,
+    current_user: Annotated[str, Depends(get_current_username)],
+) -> bool:
+    pending = session.exec(
+        select(TripMember.id).where(TripMember.user == current_user, TripMember.joined_at.is_(None)).limit(1)
+    ).first()
+    return bool(pending)
+
+
 @router.get("/{trip_id}", response_model=TripRead)
 def read_trip(
     session: SessionDep, trip_id: int, current_user: Annotated[str, Depends(get_current_username)]
 ) -> TripRead:
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
     return TripRead.serialize(db_trip)
 
 
@@ -42,10 +129,7 @@ def read_trip(
 def create_trip(
     trip: TripCreate, session: SessionDep, current_user: Annotated[str, Depends(get_current_username)]
 ) -> TripReadBase:
-    new_trip = Trip(
-        name=trip.name,
-        user=current_user,
-    )
+    new_trip = Trip(name=trip.name, user=current_user)
 
     if trip.image:
         image_bytes = b64img_decode(trip.image)
@@ -55,17 +139,10 @@ def create_trip(
 
         image = Image(filename=filename, user=current_user)
         session.add(image)
-        session.commit()
+        session.flush()
         session.refresh(image)
         new_trip.image_id = image.id
 
-    if trip.place_ids:
-        for place_id in trip.place_ids:
-            db_place = session.get(Place, place_id)
-            verify_exists_and_owns(current_user, db_place)
-            session.add(TripPlaceLink(trip_id=new_trip.id, place_id=db_place.id))
-        session.commit()
-
     session.add(new_trip)
     session.commit()
     session.refresh(new_trip)
@@ -79,8 +156,8 @@ def update_trip(
     trip: TripUpdate,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripRead:
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
 
     if db_trip.archived and (trip.archived is not False):
         raise HTTPException(status_code=400, detail="Bad request")
@@ -100,8 +177,8 @@ def update_trip(
 
         image = Image(filename=filename, user=current_user)
         session.add(image)
-        session.commit()
         session.refresh(image)
+        session.flush()
 
         if db_trip.image_id:
             old_image = session.get(Image, db_trip.image_id)
@@ -117,11 +194,16 @@ def update_trip(
 
     place_ids = trip_data.pop("place_ids", None)
     if place_ids is not None:  # Could be empty [], so 'in'
-        db_trip.places.clear()
+        allowed_users = _trip_usernames(session, trip_id)
+        new_places = []
         for place_id in place_ids:
             db_place = session.get(Place, place_id)
-            verify_exists_and_owns(current_user, db_place)
-            db_trip.places.append(db_place)
+            if not db_place:
+                raise HTTPException(status_code=404, detail="Not found")
+            if db_place.user not in allowed_users:
+                raise HTTPException(status_code=403, detail="Place not accessible by trip members")
+            new_places.append(db_place)
+        db_trip.places = new_places
 
         item_place_ids = {
             item.place.id for day in db_trip.days for item in day.items if item.place is not None
@@ -143,8 +225,8 @@ def update_trip(
 def delete_trip(
     session: SessionDep, trip_id: int, current_user: Annotated[str, Depends(get_current_username)]
 ):
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
 
     if db_trip.archived:
         raise HTTPException(status_code=400, detail="Bad request")
@@ -171,13 +253,13 @@ def create_tripday(
     session: SessionDep,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripDayRead:
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
 
     if db_trip.archived:
         raise HTTPException(status_code=400, detail="Bad request")
 
-    new_day = TripDay(label=td.label, trip_id=trip_id, user=current_user)
+    new_day = TripDay(label=td.label, trip_id=trip_id)
 
     session.add(new_day)
     session.commit()
@@ -193,15 +275,14 @@ def update_tripday(
     session: SessionDep,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripDayRead:
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
 
     if db_trip.archived:
         raise HTTPException(status_code=400, detail="Bad request")
 
     db_day = session.get(TripDay, day_id)
-    verify_exists_and_owns(current_user, db_day)
-    if db_day.trip_id != trip_id:
+    if not db_day or (db_day.trip_id != trip_id):
         raise HTTPException(status_code=400, detail="Bad request")
 
     td_data = td.model_dump(exclude_unset=True)
@@ -221,15 +302,14 @@ def delete_tripday(
     day_id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ):
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
 
     if db_trip.archived:
         raise HTTPException(status_code=400, detail="Bad request")
 
     db_day = session.get(TripDay, day_id)
-    verify_exists_and_owns(current_user, db_day)
-    if db_day.trip_id != trip_id:
+    if not db_day or (db_day.trip_id != trip_id):
         raise HTTPException(status_code=400, detail="Bad request")
 
     session.delete(db_day)
@@ -245,14 +325,14 @@ def create_tripitem(
     session: SessionDep,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripItemRead:
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
 
     if db_trip.archived:
         raise HTTPException(status_code=400, detail="Bad request")
 
     db_day = session.get(TripDay, day_id)
-    if db_day.trip_id != trip_id:
+    if not db_day or (db_day.trip_id != trip_id):
         raise HTTPException(status_code=400, detail="Bad request")
 
     new_item = TripItem(
@@ -266,7 +346,7 @@ def create_tripitem(
         status=item.status,
     )
 
-    if item.place and item.place != "":
+    if item.place is not None:
         place_in_trip = any(place.id == item.place for place in db_trip.places)
         if not place_in_trip:
             raise HTTPException(status_code=400, detail="Bad request")
@@ -287,18 +367,18 @@ def update_tripitem(
     session: SessionDep,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripItemRead:
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
 
     if db_trip.archived:
         raise HTTPException(status_code=400, detail="Bad request")
 
     db_day = session.get(TripDay, day_id)
-    if db_day.trip_id != trip_id:
+    if not db_day or (db_day.trip_id != trip_id):
         raise HTTPException(status_code=400, detail="Bad request")
 
     db_item = session.get(TripItem, item_id)
-    if db_item.day_id != day_id:
+    if not db_item or (db_item.day_id != day_id):
         raise HTTPException(status_code=400, detail="Bad request")
 
     item_data = item.model_dump(exclude_unset=True)
@@ -327,18 +407,18 @@ def delete_tripitem(
     item_id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ):
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
 
     if db_trip.archived:
         raise HTTPException(status_code=400, detail="Bad request")
 
     db_day = session.get(TripDay, day_id)
-    if db_day.trip_id != trip_id:
+    if not db_day or (db_day.trip_id != trip_id):
         raise HTTPException(status_code=400, detail="Bad request")
 
     db_item = session.get(TripItem, item_id)
-    if db_item.day_id != day_id:
+    if not db_item or (db_item.day_id != day_id):
         raise HTTPException(status_code=400, detail="Bad request")
 
     session.delete(db_item)
@@ -351,11 +431,7 @@ def read_shared_trip(
     session: SessionDep,
     token: str,
 ) -> TripRead:
-    share = session.exec(select(TripShare).where(TripShare.token == token)).first()
-    if not share:
-        raise HTTPException(status_code=404, detail="Not found")
-
-    db_trip = session.get(Trip, share.trip_id)
+    db_trip = session.get(Trip, _trip_from_token_or_404(session, token).trip_id)
     return TripRead.serialize(db_trip)
 
 
@@ -365,8 +441,7 @@ def get_shared_trip_url(
     trip_id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripShareURL:
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    _verify_trip_member(session, trip_id, current_user)
 
     share = session.exec(select(TripShare).where(TripShare.trip_id == trip_id)).first()
     if not share:
@@ -381,15 +456,14 @@ def create_shared_trip(
     trip_id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripShareURL:
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    _verify_trip_member(session, trip_id, current_user)
 
     shared = session.exec(select(TripShare).where(TripShare.trip_id == trip_id)).first()
     if shared:
         raise HTTPException(status_code=409, detail="The resource already exists")
 
     token = generate_urlsafe()
-    trip_share = TripShare(token=token, trip_id=trip_id, user=current_user)
+    trip_share = TripShare(token=token, trip_id=trip_id)
     session.add(trip_share)
     session.commit()
     return {"url": f"/s/t/{token}"}
@@ -401,8 +475,7 @@ def delete_shared_trip(
     trip_id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ):
-    db_trip = session.get(Trip, trip_id)
-    verify_exists_and_owns(current_user, db_trip)
+    _verify_trip_member(session, trip_id, current_user)
 
     db_share = session.exec(select(TripShare).where(TripShare.trip_id == trip_id)).first()
     if not db_share:
@@ -419,15 +492,25 @@ def read_packing_list(
     trip_id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> list[TripPackingListItemRead]:
-    p_items = session.exec(
-        select(TripPackingListItem)
-        .where(TripPackingListItem.trip_id == trip_id, TripPackingListItem.user == current_user)
-        .order_by(TripPackingListItem.id.asc())
-    ).all()
+    _verify_trip_member(session, trip_id, current_user)
+    p_items = session.exec(select(TripPackingListItem).where(TripPackingListItem.trip_id == trip_id))
 
     return [TripPackingListItemRead.serialize(i) for i in p_items]
 
 
+@router.get("/shared/{token}/packing", response_model=list[TripPackingListItemRead])
+def read_shared_trip_packing_list(
+    session: SessionDep,
+    token: str,
+) -> list[TripPackingListItemRead]:
+    p_items = session.exec(
+        select(TripPackingListItem).where(
+            TripPackingListItem.trip_id == _trip_from_token_or_404(session, token).trip_id
+        )
+    )
+    return [TripPackingListItemRead.serialize(i) for i in p_items]
+
+
 @router.post("/{trip_id}/packing", response_model=TripPackingListItemRead)
 def create_packing_item(
     session: SessionDep,
@@ -435,11 +518,8 @@ def create_packing_item(
     data: TripPackingListItemCreate,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripPackingListItemRead:
-    item = TripPackingListItem(
-        **data.model_dump(),
-        trip_id=trip_id,
-        user=current_user,
-    )
+    _verify_trip_member(session, trip_id, current_user)
+    item = TripPackingListItem(**data.model_dump(), trip_id=trip_id)
     session.add(item)
     session.commit()
     session.refresh(item)
@@ -454,11 +534,10 @@ def update_packing_item(
     p_id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripPackingListItemRead:
+    _verify_trip_member(session, trip_id, current_user)
     db_item = session.exec(
         select(TripPackingListItem).where(
-            TripPackingListItem.id == p_id,
-            TripPackingListItem.trip_id == trip_id,
-            TripPackingListItem.user == current_user,
+            TripPackingListItem.id == p_id, TripPackingListItem.trip_id == trip_id
         )
     ).one_or_none()
 
@@ -482,11 +561,10 @@ def delete_packing_item(
     p_id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ):
+    _verify_trip_member(session, trip_id, current_user)
     item = session.exec(
         select(TripPackingListItem).where(
-            TripPackingListItem.id == p_id,
-            TripPackingListItem.trip_id == trip_id,
-            TripPackingListItem.user == current_user,
+            TripPackingListItem.id == p_id, TripPackingListItem.trip_id == trip_id
         )
     ).one_or_none()
 
@@ -504,11 +582,8 @@ def read_checklist(
     trip_id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> list[TripChecklistItemRead]:
-    items = session.exec(
-        select(TripChecklistItem).where(
-            TripChecklistItem.trip_id == trip_id, TripChecklistItem.user == current_user
-        )
-    )
+    _verify_trip_member(session, trip_id, current_user)
+    items = session.exec(select(TripChecklistItem).where(TripChecklistItem.trip_id == trip_id))
     return [TripChecklistItemRead.serialize(i) for i in items]
 
 
@@ -532,11 +607,8 @@ def create_checklist_item(
     data: TripChecklistItemCreate,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripChecklistItemRead:
-    item = TripChecklistItem(
-        **data.model_dump(),
-        trip_id=trip_id,
-        user=current_user,
-    )
+    _verify_trip_member(session, trip_id, current_user)
+    item = TripChecklistItem(**data.model_dump(), trip_id=trip_id)
     session.add(item)
     session.commit()
     session.refresh(item)
@@ -551,12 +623,9 @@ def update_checklist_item(
     id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ) -> TripChecklistItemRead:
+    _verify_trip_member(session, trip_id, current_user)
     db_item = session.exec(
-        select(TripChecklistItem).where(
-            TripChecklistItem.id == id,
-            TripChecklistItem.trip_id == trip_id,
-            TripChecklistItem.user == current_user,
-        )
+        select(TripChecklistItem).where(TripChecklistItem.id == id, TripChecklistItem.trip_id == trip_id)
     ).one_or_none()
 
     if not db_item:
@@ -579,11 +648,11 @@ def delete_checklist_item(
     id: int,
     current_user: Annotated[str, Depends(get_current_username)],
 ):
+    _verify_trip_member(session, trip_id, current_user)
     item = session.exec(
         select(TripChecklistItem).where(
             TripChecklistItem.id == id,
             TripChecklistItem.trip_id == trip_id,
-            TripChecklistItem.user == current_user,
         )
     ).one_or_none()
 
@@ -593,3 +662,122 @@ def delete_checklist_item(
     session.delete(item)
     session.commit()
     return {}
+
+
+@router.get("/{trip_id}/members", response_model=list[TripMemberRead])
+def read_trip_members(
+    session: SessionDep, trip_id: int, current_user: Annotated[str, Depends(get_current_username)]
+) -> list[TripMemberRead]:
+    _verify_trip_member(session, trip_id, current_user)
+
+    members: list[TripMemberRead] = []
+    owner = session.exec(select(Trip.user).where(Trip.id == trip_id)).first()
+    members.append(TripMemberRead(user=owner, invited_by=None, invited_at=None, joined_at=None))
+
+    db_members = session.exec(select(TripMember).where(TripMember.trip_id == trip_id)).all()
+    members.extend(TripMemberRead.serialize(m) for m in db_members)
+    return members
+
+
+@router.post("/{trip_id}/members", response_model=TripMemberRead)
+def invite_trip_member(
+    session: SessionDep,
+    trip_id: int,
+    data: TripMemberCreate,
+    current_user: Annotated[str, Depends(get_current_username)],
+) -> TripMemberRead:
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
+
+    if db_trip.user == data.user:
+        raise HTTPException(status_code=409, detail="The resource already exists")
+
+    exists = session.exec(
+        select(TripMember.id)
+        .where(
+            TripMember.trip_id == trip_id,
+            TripMember.user == data.user,
+        )
+        .limit(1)
+    ).first()
+    if exists:
+        raise HTTPException(status_code=409, detail="The resource already exists")
+
+    db_user = session.get(User, data.user)
+    print(data.user, db_user)
+    if not db_user:
+        raise HTTPException(status_code=404, detail="Not found")
+
+    new_member = TripMember(trip_id=trip_id, user=data.user, invited_by=current_user)
+    session.add(new_member)
+    session.commit()
+    session.refresh(new_member)
+    return TripMemberRead.serialize(new_member)
+
+
+@router.delete("/{trip_id}/members/{username}")
+def delete_trip_member(
+    session: SessionDep,
+    trip_id: int,
+    username: str,
+    current_user: Annotated[str, Depends(get_current_username)],
+):
+    print("yo")
+    db_trip = _get_trip_or_404(session, trip_id)
+    _verify_trip_member(session, trip_id, current_user)
+
+    if current_user == db_trip.user and current_user == username:
+        raise HTTPException(status_code=400, detail="Bad request")
+
+    if current_user != db_trip.user and current_user != username:
+        raise HTTPException(status_code=403, detail="Forbidden")
+
+    member = session.exec(
+        select(TripMember).where(
+            TripMember.user == username,
+            TripMember.trip_id == trip_id,
+        )
+    ).one_or_none()
+    if not member:
+        raise HTTPException(status_code=404, detail="Not found")
+
+    session.delete(member)
+    session.commit()
+    return {}
+
+
+@router.post("/{trip_id}/members/accept")
+def accept_invite(
+    session: SessionDep,
+    trip_id: int,
+    current_user: Annotated[str, Depends(get_current_username)],
+):
+    db_member = session.exec(
+        select(TripMember).where(TripMember.trip_id == trip_id, TripMember.user == current_user)
+    ).one_or_none()
+    if not db_member:
+        raise HTTPException(status_code=404, detail="Not found")
+    if db_member.joined_at:
+        raise HTTPException(status_code=409, detail="Already a member")
+    db_member.joined_at = utc_now()
+    session.add(db_member)
+    session.commit()
+    return {}
+
+
+@router.post("/{trip_id}/members/decline")
+def decline_invite(
+    session: SessionDep,
+    trip_id: int,
+    current_user: Annotated[str, Depends(get_current_username)],
+):
+    db_member = session.exec(
+        select(TripMember).where(TripMember.trip_id == trip_id, TripMember.user == current_user)
+    ).one_or_none()
+    if not db_member:
+        raise HTTPException(status_code=404, detail="Not found")
+    if db_member.joined_at:
+        raise HTTPException(status_code=409, detail="Already a member")
+    session.delete(db_member)
+    session.commit()
+    return {}
diff --git a/backend/trip/utils/utils.py b/backend/trip/utils/utils.py
index 7d4ddb4..19f4c2e 100644
--- a/backend/trip/utils/utils.py
+++ b/backend/trip/utils/utils.py
@@ -1,5 +1,5 @@
 import base64
-from datetime import date
+from datetime import UTC, date, datetime
 from io import BytesIO
 from pathlib import Path
 from secrets import token_urlsafe
@@ -48,6 +48,10 @@ def remove_image(path: str):
         raise Exception("Error deleting image:", exc, path)
 
 
+def utc_now():
+    return datetime.now(UTC)
+
+
 def parse_str_or_date_to_date(cdate: str | date) -> date:
     if isinstance(cdate, str):
         try:
diff --git a/src/src/app/components/trip/trip.component.html b/src/src/app/components/trip/trip.component.html
index 08aece1..64c7284 100644
--- a/src/src/app/components/trip/trip.component.html
+++ b/src/src/app/components/trip/trip.component.html
@@ -15,6 +15,7 @@
     <div class="flex items-center gap-2 print:hidden">
       @if (!trip?.archived) {
       <div class="hidden md:flex items-center gap-2">
+        <p-button pTooltip="Manage users" text (click)="openMembersDialog()" icon="pi pi-users" />
         <p-button pTooltip="Share Trip" text (click)="shareDialogVisible = true" icon="pi pi-share-alt" />
         <p-button pTooltip="Archive Trip" text (click)="toggleArchiveTrip()" icon="pi pi-box" severity="warn" />
         <div class="border-l border-solid border-gray-700 h-4"></div>
@@ -615,4 +616,60 @@
       }
     </div>
   </section>
+</p-dialog>
+
+<p-dialog header="Members" [draggable]="false" [dismissableMask]="true" [modal]="true"
+  [(visible)]="membersDialogVisible" styleClass="w-[95%] md:w-[40%] lg:w-[30%]">
+  <section class="p-4 max-w-full max-h-[80%] md:max-h-[600px]">
+    <div class="flex justify-center">
+      <p-button (click)="addMember()" icon="pi pi-plus" label="Member" text />
+    </div>
+
+    <div class="divide-y divide-gray-100 mt-4 pb-4">
+      @for (m of tripMembers; track m.user) {
+      <div class="flex items-center justify-between gap-x-6 py-5">
+        <div class="flex items-center min-w-0 gap-x-4">
+          <div class="size-12 flex flex-none rounded-full items-center justify-center" [ngClass]="{
+            'bg-red-100': !m.invited_at,
+            'bg-gray-50': m.invited_at && !m.joined_at,
+            'bg-blue-100': m.invited_at && m.joined_at
+            }">
+            <i class="pi pi-user"></i>
+          </div>
+
+          <div class="flex min-w-0 gap-x-4">
+            <span class="capitalize truncate font-semibold text-gray-900">{{ m.user }}</span>
+          </div>
+        </div>
+
+        <div class="flex items-center gap-2">
+          <span
+            class="text-center bg-gray-100 text-gray-800 text-xs px-2.5 py-0.5 rounded-md group-hover:hidden dark:bg-gray-100/85">-
+            {{ currency$ | async }}</span>
+
+          <div class="hidden shrink-0 sm:flex sm:flex-col sm:items-end">
+            @if (!m.invited_at) {
+            <span
+              class="text-center bg-red-100 text-red-800 text-xs px-2.5 py-0.5 rounded-md group-hover:hidden dark:bg-red-100/85">Owner</span>
+            }
+
+            @if (m.invited_at && !m.joined_at) {
+            <span
+              class="text-center bg-gray-100 text-gray-800 text-xs px-2.5 py-0.5 rounded-md group-hover:hidden dark:bg-gray-100/85">Invited</span>
+            }
+
+            @if (m.joined_at) {
+            <span
+              class="text-center bg-blue-100 text-blue-800 text-xs px-2.5 py-0.5 rounded-md group-hover:hidden dark:bg-blue-100/85">Member</span>
+            }
+          </div>
+
+          @if (m.invited_at) {
+          <p-button text (click)="deleteMember(m.user)" icon="pi pi-trash" severity="danger" />
+          }
+        </div>
+      </div>
+      }
+    </div>
+  </section>
 </p-dialog>
\ No newline at end of file
diff --git a/src/src/app/components/trip/trip.component.ts b/src/src/app/components/trip/trip.component.ts
index f8574e6..da205b7 100644
--- a/src/src/app/components/trip/trip.component.ts
+++ b/src/src/app/components/trip/trip.component.ts
@@ -16,6 +16,7 @@ import {
   TripStatus,
   PackingItem,
   ChecklistItem,
+  TripMember,
 } from "../../types/trip";
 import { Place } from "../../types/poi";
 import {
@@ -57,6 +58,7 @@ import { takeUntilDestroyed } from "@angular/core/rxjs-interop";
 import { CheckboxChangeEvent, CheckboxModule } from "primeng/checkbox";
 import { TripCreatePackingModalComponent } from "../../modals/trip-create-packing-modal/trip-create-packing-modal.component";
 import { TripCreateChecklistModalComponent } from "../../modals/trip-create-checklist-modal/trip-create-checklist-modal.component";
+import { TripInviteMemberModalComponent } from "../../modals/trip-invite-member-modal/trip-invite-member-modal.component";
 
 @Component({
   selector: "app-trip",
@@ -106,6 +108,8 @@ export class TripComponent implements AfterViewInit {
   checklistDialogVisible = false;
   checklistItems: ChecklistItem[] = [];
   dispchecklist: ChecklistItem[] = [];
+  membersDialogVisible = false;
+  tripMembers: TripMember[] = [];
 
   map?: L.Map;
   markerClusterGroup?: L.MarkerClusterGroup;
@@ -134,6 +138,14 @@ export class TripComponent implements AfterViewInit {
             this.openChecklist();
           },
         },
+        {
+          label: "Members",
+          icon: "pi pi-users",
+          iconClass: "text-blue-500!",
+          command: () => {
+            this.openMembersDialog();
+          },
+        },
         {
           label: "Edit",
           icon: "pi pi-pencil",
@@ -1552,4 +1564,84 @@ export class TripComponent implements AfterViewInit {
       },
     });
   }
+
+  openMembersDialog() {
+    if (!this.trip) return;
+
+    if (!this.tripMembers.length)
+      this.apiService
+        .getTripMembers(this.trip.id)
+        .pipe(take(1))
+        .subscribe({
+          next: (items) => {
+            this.tripMembers = [...items];
+          },
+        });
+    this.membersDialogVisible = true;
+  }
+
+  addMember() {
+    if (!this.trip) return;
+
+    const modal: DynamicDialogRef = this.dialogService.open(
+      TripInviteMemberModalComponent,
+      {
+        header: "Invite member",
+        modal: true,
+        appendTo: "body",
+        closable: true,
+        dismissableMask: true,
+        width: "40vw",
+        breakpoints: {
+          "1260px": "70vw",
+          "600px": "90vw",
+        },
+      },
+    );
+
+    modal.onClose.pipe(take(1)).subscribe({
+      next: (user: string | null) => {
+        if (!user) return;
+
+        this.apiService
+          .inviteTripMember(this.trip!.id, user)
+          .pipe(take(1))
+          .subscribe({
+            next: (member) => {
+              this.tripMembers = [...this.tripMembers, member];
+            },
+          });
+      },
+    });
+  }
+
+  deleteMember(username: string) {
+    const modal = this.dialogService.open(YesNoModalComponent, {
+      header: "Confirm deletion",
+      modal: true,
+      closable: true,
+      dismissableMask: true,
+      breakpoints: {
+        "640px": "90vw",
+      },
+      data: `Delete ${username.substring(0, 50)} from Trip ?`,
+    });
+
+    modal.onClose.pipe(take(1)).subscribe({
+      next: (bool) => {
+        if (!bool) return;
+        this.apiService
+          .deleteTripMember(this.trip!.id, username)
+          .pipe(take(1))
+          .subscribe({
+            next: () => {
+              const index = this.tripMembers.findIndex(
+                (p) => p.user == username,
+              );
+              if (index > -1) this.tripMembers.splice(index, 1);
+            },
+          });
+      },
+    });
+  }
 }
diff --git a/src/src/app/components/trips/trips.component.html b/src/src/app/components/trips/trips.component.html
index ea9c294..9a6751b 100644
--- a/src/src/app/components/trips/trips.component.html
+++ b/src/src/app/components/trips/trips.component.html
@@ -4,7 +4,10 @@
       <img src="favicon.png" (click)="gotoMap()" class="cursor-pointer w-24" />
     </div>
     <div class="flex gap-2">
-      <p-button icon="pi pi-map" (click)="gotoMap()" text />
+      <div class="relative">
+        <p-button icon="pi pi-bell" (click)="toggleInvitations()" text />
+        @if(hasPendingInvitations) {<div class="absolute top-1 right-2 size-2 bg-red-400 rounded-full"></div>}
+      </div>
       <p-button icon="pi pi-plus" (click)="addTrip()" text />
     </div>
   </div>
@@ -19,7 +22,13 @@
 
       <div class="absolute inset-0 bg-black/5 flex flex-col justify-end p-4 text-white">
         <h3 class="text-lg font-semibold line-clamp-2">{{ trip.name }}</h3>
-        <p class="text-sm ">{{ trip.days || 0 }} {{ trip.days > 1 ? 'days' : 'day'}}</p>
+
+        <div class="flex items-center gap-2 text-sm">
+          <p>{{ trip.days || 0 }} {{ trip.days > 1 ? 'days' : 'day'}}</p>
+          @if (trip.collaborators.length) {- <p>{{ trip.collaborators.length + 1 }} user{{ trip.collaborators.length > 0
+            ? 's'
+            : '' }}</p>}
+        </div>
 
         <i
           class="pi pi-arrow-right text-xl absolute right-4 bottom-4 h-4 opacity-0 -translate-x-4 group-hover:opacity-100 group-hover:translate-x-0 transition-all duration-300"></i>
@@ -48,4 +57,40 @@
     }
     }
   </div>
-</div>
\ No newline at end of file
+</div>
+
+<p-dialog header="Invitations" [draggable]="false" [dismissableMask]="true" [modal]="true"
+  [(visible)]="invitationsDialogVisible" styleClass="w-[95%] md:w-[40%] lg:w-[30%]">
+  <section class="p-4 max-w-full max-h-[80%] md:max-h-[600px]">
+    <div class="divide-y divide-gray-100">
+      @for (inv of invitations; track inv.id) {
+      <div class="flex items-center justify-between gap-x-6 py-5">
+        <div class="flex items-center min-w-0 gap-x-4">
+          <img [src]="inv.image" class="w-20 rounded-full object-cover">
+
+          <div class="flex flex-col min-w-0 gap-1">
+            <div class="capitalize truncate text-md font-semibold text-gray-900">{{ inv.name }}</div>
+            <div class="text-xs md:text-sm text-gray-500">On <i>{{ inv.invited_at | date: 'short'}}</i>, <i>{{
+                inv.invited_by
+                }}</i> invited you to collaborate </div>
+
+            <div class="flex justify-center md:hidden gap-4">
+              <p-button text (click)="acceptInvitation(inv.id)" icon="pi pi-check" severity="success" />
+              <p-button text (click)="declineInvitation(inv.id)" icon="pi pi-times" severity="danger" />
+            </div>
+          </div>
+        </div>
+
+        <div class="hidden md:flex gap-4">
+          <p-button text (click)="acceptInvitation(inv.id)" icon="pi pi-check" severity="success" />
+          <p-button text (click)="declineInvitation(inv.id)" icon="pi pi-times" severity="danger" />
+        </div>
+      </div>
+      } @empty {
+      <div class="text-center">
+        No invitation
+      </div>
+      }
+    </div>
+  </section>
+</p-dialog>
\ No newline at end of file
diff --git a/src/src/app/components/trips/trips.component.ts b/src/src/app/components/trips/trips.component.ts
index eb88f85..c24632e 100644
--- a/src/src/app/components/trips/trips.component.ts
+++ b/src/src/app/components/trips/trips.component.ts
@@ -2,11 +2,13 @@ import { Component, OnInit } from "@angular/core";
 import { ApiService } from "../../services/api.service";
 import { ButtonModule } from "primeng/button";
 import { SkeletonModule } from "primeng/skeleton";
-import { TripBase } from "../../types/trip";
+import { TripBase, TripInvitation } from "../../types/trip";
 import { DialogService, DynamicDialogRef } from "primeng/dynamicdialog";
 import { TripCreateModalComponent } from "../../modals/trip-create-modal/trip-create-modal.component";
 import { Router } from "@angular/router";
 import { forkJoin, take } from "rxjs";
+import { DatePipe } from "@angular/common";
+import { DialogModule } from "primeng/dialog";
 
 interface TripBaseWithDates extends TripBase {
   from?: Date;
@@ -16,12 +18,15 @@ interface TripBaseWithDates extends TripBase {
 @Component({
   selector: "app-trips",
   standalone: true,
-  imports: [SkeletonModule, ButtonModule],
+  imports: [SkeletonModule, ButtonModule, DialogModule, DatePipe],
   templateUrl: "./trips.component.html",
   styleUrls: ["./trips.component.scss"],
 })
 export class TripsComponent implements OnInit {
   trips: TripBase[] = [];
+  hasPendingInvitations = false;
+  invitations: TripInvitation[] = [];
+  invitationsDialogVisible = false;
 
   constructor(
     private apiService: ApiService,
@@ -39,6 +44,12 @@ export class TripsComponent implements OnInit {
           this.sortTrips();
         },
       });
+    this.apiService
+      .getHasTripsInvitations()
+      .pipe(take(1))
+      .subscribe({
+        next: (bool) => (this.hasPendingInvitations = bool),
+      });
   }
 
   gotoMap() {
@@ -137,4 +148,50 @@ export class TripsComponent implements OnInit {
     }
     return labels;
   }
+
+  toggleInvitations() {
+    if (!this.invitations.length)
+      this.apiService
+        .getTripsInvitations()
+        .pipe(take(1))
+        .subscribe({
+          next: (items) => {
+            this.invitations = [...items];
+          },
+        });
+    this.invitationsDialogVisible = true;
+  }
+
+  removeInvitationAndHide(trip_id: number) {
+    this.invitations = this.invitations.filter((inv) => inv.id != trip_id);
+    this.hasPendingInvitations = !!this.invitations.length;
+    this.invitationsDialogVisible = false;
+  }
+
+  acceptInvitation(trip_id: number) {
+    this.apiService
+      .acceptTripMemberInvite(trip_id)
+      .pipe(take(1))
+      .subscribe({
+        next: () => {
+          const index = this.invitations.findIndex((inv) => inv.id == trip_id);
+          if (index > -1) {
+            this.trips = [...this.trips, this.invitations[index]];
+            this.sortTrips();
+          }
+          this.removeInvitationAndHide(trip_id);
+        },
+      });
+  }
+
+  declineInvitation(trip_id: number) {
+    this.apiService
+      .declineTripMemberInvite(trip_id)
+      .pipe(take(1))
+      .subscribe({
+        next: () => {
+          this.removeInvitationAndHide(trip_id);
+        },
+      });
+  }
 }
diff --git a/src/src/app/modals/trip-invite-member-modal/trip-invite-member-modal.component.html b/src/src/app/modals/trip-invite-member-modal/trip-invite-member-modal.component.html
new file mode 100644
index 0000000..6c9a135
--- /dev/null
+++ b/src/src/app/modals/trip-invite-member-modal/trip-invite-member-modal.component.html
@@ -0,0 +1,9 @@
+<div pFocusTrap class="grid items-center gap-4">
+  <p-floatlabel variant="in">
+    <input class="col-span-2" id="name" [formControl]="memberForm" (keypress.enter)="closeDialog()" pInputText fluid />
+    <label for="name">Name</label>
+  </p-floatlabel>
+
+  <div class="mt-4 text-right">
+    <p-button (click)="closeDialog()" [disabled]="!memberForm.value">Invite</p-button>
+  </div>
\ No newline at end of file
diff --git a/src/src/app/modals/trip-invite-member-modal/trip-invite-member-modal.component.scss b/src/src/app/modals/trip-invite-member-modal/trip-invite-member-modal.component.scss
new file mode 100644
index 0000000..e69de29
diff --git a/src/src/app/modals/trip-invite-member-modal/trip-invite-member-modal.component.ts b/src/src/app/modals/trip-invite-member-modal/trip-invite-member-modal.component.ts
new file mode 100644
index 0000000..5bd1f0f
--- /dev/null
+++ b/src/src/app/modals/trip-invite-member-modal/trip-invite-member-modal.component.ts
@@ -0,0 +1,32 @@
+import { Component } from "@angular/core";
+import { FormControl, ReactiveFormsModule } from "@angular/forms";
+import { ButtonModule } from "primeng/button";
+import { DynamicDialogRef } from "primeng/dynamicdialog";
+import { FloatLabelModule } from "primeng/floatlabel";
+import { InputTextModule } from "primeng/inputtext";
+import { FocusTrapModule } from "primeng/focustrap";
+
+@Component({
+  selector: "app-trip-invite-member-modal",
+  imports: [
+    FloatLabelModule,
+    InputTextModule,
+    ButtonModule,
+    ReactiveFormsModule,
+    FocusTrapModule,
+  ],
+  standalone: true,
+  templateUrl: "./trip-invite-member-modal.component.html",
+  styleUrl: "./trip-invite-member-modal.component.scss",
+})
+export class TripInviteMemberModalComponent {
+  memberForm = new FormControl("");
+  constructor(private ref: DynamicDialogRef) {}
+
+  closeDialog() {
+    if (!this.memberForm.value) return;
+
+    // Normalize data for API POST
+    this.ref.close(this.memberForm.value);
+  }
+}
diff --git a/src/src/app/services/api.service.ts b/src/src/app/services/api.service.ts
index 4ecf23a..af58513 100644
--- a/src/src/app/services/api.service.ts
+++ b/src/src/app/services/api.service.ts
@@ -1,5 +1,5 @@
 import { inject, Injectable } from "@angular/core";
-import { HttpClient } from "@angular/common/http";
+import { HttpClient, HttpHeaders } from "@angular/common/http";
 import { Category, Place } from "../types/poi";
 import { BehaviorSubject, map, Observable, shareReplay, tap } from "rxjs";
 import { Info } from "../types/info";
@@ -11,7 +11,9 @@ import {
   Trip,
   TripBase,
   TripDay,
+  TripInvitation,
   TripItem,
+  TripMember,
 } from "../types/trip";
 
 const NO_AUTH_HEADER = {
@@ -312,6 +314,51 @@ export class ApiService {
     );
   }
 
+  getHasTripsInvitations(): Observable<boolean> {
+    return this.httpClient.get<boolean>(
+      `${this.apiBaseUrl}/trips/invitations/pending`,
+    );
+  }
+
+  getTripsInvitations(): Observable<TripInvitation[]> {
+    return this.httpClient.get<TripInvitation[]>(
+      `${this.apiBaseUrl}/trips/invitations`,
+    );
+  }
+
+  getTripMembers(trip_id: number): Observable<TripMember[]> {
+    return this.httpClient.get<TripMember[]>(
+      `${this.apiBaseUrl}/trips/${trip_id}/members`,
+    );
+  }
+
+  deleteTripMember(trip_id: number, username: string): Observable<null> {
+    return this.httpClient.delete<null>(
+      `${this.apiBaseUrl}/trips/${trip_id}/members/${username}`,
+    );
+  }
+
+  inviteTripMember(trip_id: number, user: string): Observable<TripMember> {
+    return this.httpClient.post<TripMember>(
+      `${this.apiBaseUrl}/trips/${trip_id}/members`,
+      { user },
+    );
+  }
+
+  acceptTripMemberInvite(trip_id: number): Observable<null> {
+    return this.httpClient.post<null>(
+      `${this.apiBaseUrl}/trips/${trip_id}/members/accept`,
+      {},
+    );
+  }
+
+  declineTripMemberInvite(trip_id: number): Observable<null> {
+    return this.httpClient.post<null>(
+      `${this.apiBaseUrl}/trips/${trip_id}/members/decline`,
+      {},
+    );
+  }
+
   checkVersion(): Observable<string> {
     return this.httpClient.get<string>(
       `${this.apiBaseUrl}/settings/checkversion`,
diff --git a/src/src/app/types/trip.ts b/src/src/app/types/trip.ts
index 9c297c2..e685109 100644
--- a/src/src/app/types/trip.ts
+++ b/src/src/app/types/trip.ts
@@ -7,6 +7,7 @@ export interface TripBase {
   archived?: boolean;
   user: string;
   days: number;
+  collaborators: TripMember[];
 }
 
 export interface Trip {
@@ -16,6 +17,7 @@ export interface Trip {
   archived?: boolean;
   user: string;
   days: TripDay[];
+  collaborators: TripMember[];
 
   // POST / PUT
   places: Place[];
@@ -62,6 +64,18 @@ export interface FlattenedTripItem {
   status?: TripStatus;
 }
 
+export interface TripMember {
+  user: string;
+  invited_by: string;
+  invited_at: string;
+  joined_at?: string;
+}
+
+export interface TripInvitation extends TripBase {
+  invited_by: string;
+  invited_at: string;
+}
+
 export interface SharedTripURL {
   url: string;
 }
@@ -78,4 +92,4 @@ export interface ChecklistItem {
   id: number;
   text: string;
   checked?: boolean;
-}
\ No newline at end of file
+}