diff --git a/.github/workflows/playwright.yml b/.github/workflows/playwright.yml
index d4c6247269..0a8a942184 100644
--- a/.github/workflows/playwright.yml
+++ b/.github/workflows/playwright.yml
@@ -91,7 +91,7 @@ jobs:
     - name: Install dependencies
       run: bun ci
     - name: Download blob reports from GitHub Actions Artifacts
-      uses: actions/download-artifact@v8
+      uses: actions/download-artifact@v7
       with:
         path: frontend/all-blob-reports
         pattern: blob-report-*
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 9f19448ef5..39771c3fab 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -47,6 +47,13 @@ repos:
         language: unsupported
         pass_filenames: false
 
+      - id: local-ty
+        name: ty check
+        entry: uv run ty check backend/app
+        require_serial: true
+        language: unsupported
+        pass_filenames: false
+
       - id: generate-frontend-sdk
         name: Generate Frontend SDK
         entry: bash ./scripts/generate-client.sh
diff --git a/backend/app/alembic/env.py b/backend/app/alembic/env.py
index 5e2c22f844..fb993cf48c 100755
--- a/backend/app/alembic/env.py
+++ b/backend/app/alembic/env.py
@@ -63,6 +63,7 @@ def run_migrations_online():
 
     """
     configuration = config.get_section(config.config_ini_section)
+    assert configuration is not None
     configuration["sqlalchemy.url"] = get_url()
     connectable = engine_from_config(
         configuration,
diff --git a/backend/app/alembic/versions/1a31ce608336_add_cascade_delete_relationships.py b/backend/app/alembic/versions/1a31ce608336_add_cascade_delete_relationships.py
index 10e47a1456..a5246906df 100644
--- a/backend/app/alembic/versions/1a31ce608336_add_cascade_delete_relationships.py
+++ b/backend/app/alembic/versions/1a31ce608336_add_cascade_delete_relationships.py
@@ -29,7 +29,7 @@ def upgrade():
 
 def downgrade():
     # ### commands auto generated by Alembic - please adjust! ###
-    op.drop_constraint(None, 'item', type_='foreignkey')
+    op.drop_constraint('item_owner_id_fkey', 'item', type_='foreignkey')
     op.create_foreign_key('item_owner_id_fkey', 'item', 'user', ['owner_id'], ['id'])
     op.alter_column('item', 'owner_id',
                existing_type=sa.UUID(),
diff --git a/backend/app/api/routes/items.py b/backend/app/api/routes/items.py
index f1929e5836..f0eb30e4ce 100644
--- a/backend/app/api/routes/items.py
+++ b/backend/app/api/routes/items.py
@@ -41,7 +41,8 @@ def read_items(
         )
         items = session.exec(statement).all()
 
-    return ItemsPublic(data=items, count=count)
+    items_public = [ItemPublic.model_validate(item) for item in items]
+    return ItemsPublic(data=items_public, count=count)
 
 
 @router.get("/{id}", response_model=ItemPublic)
diff --git a/backend/app/api/routes/users.py b/backend/app/api/routes/users.py
index 35f64b626e..1748f58484 100644
--- a/backend/app/api/routes/users.py
+++ b/backend/app/api/routes/users.py
@@ -47,7 +47,8 @@ def read_users(session: SessionDep, skip: int = 0, limit: int = 100) -> Any:
     )
     users = session.exec(statement).all()
 
-    return UsersPublic(data=users, count=count)
+    users_public = [UserPublic.model_validate(user) for user in users]
+    return UsersPublic(data=users_public, count=count)
 
 
 @router.post(
diff --git a/backend/app/core/config.py b/backend/app/core/config.py
index 650b9f7910..e9036cbe56 100644
--- a/backend/app/core/config.py
+++ b/backend/app/core/config.py
@@ -41,7 +41,7 @@ class Settings(BaseSettings):
         list[AnyUrl] | str, BeforeValidator(parse_cors)
     ] = []
 
-    @computed_field  # type: ignore[prop-decorator]
+    @computed_field  # type: ignore[prop-decorator]  # ty: ignore[unused-ignore-comment]
     @property
     def all_cors_origins(self) -> list[str]:
         return [str(origin).rstrip("/") for origin in self.BACKEND_CORS_ORIGINS] + [
@@ -56,7 +56,7 @@ def all_cors_origins(self) -> list[str]:
     POSTGRES_PASSWORD: str = ""
     POSTGRES_DB: str = ""
 
-    @computed_field  # type: ignore[prop-decorator]
+    @computed_field  # type: ignore[prop-decorator]  # ty: ignore[unused-ignore-comment]
     @property
     def SQLALCHEMY_DATABASE_URI(self) -> PostgresDsn:
         return PostgresDsn.build(
@@ -85,7 +85,7 @@ def _set_default_emails_from(self) -> Self:
 
     EMAIL_RESET_TOKEN_EXPIRE_HOURS: int = 48
 
-    @computed_field  # type: ignore[prop-decorator]
+    @computed_field  # type: ignore[prop-decorator]   # ty: ignore[unused-ignore-comment]
     @property
     def emails_enabled(self) -> bool:
         return bool(self.SMTP_HOST and self.EMAILS_FROM_EMAIL)
diff --git a/backend/app/main.py b/backend/app/main.py
index 9a95801e74..2d9c7444df 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -23,7 +23,7 @@ def custom_generate_unique_id(route: APIRoute) -> str:
 # Set all CORS enabled origins
 if settings.all_cors_origins:
     app.add_middleware(
-        CORSMiddleware,
+        CORSMiddleware,  # ty: ignore
         allow_origins=settings.all_cors_origins,
         allow_credentials=True,
         allow_methods=["*"],
diff --git a/backend/app/models.py b/backend/app/models.py
index b5132e0e2c..1c65e2f6ac 100644
--- a/backend/app/models.py
+++ b/backend/app/models.py
@@ -31,7 +31,7 @@ class UserRegister(SQLModel):
 
 # Properties to receive via API on update, all are optional
 class UserUpdate(UserBase):
-    email: EmailStr | None = Field(default=None, max_length=255)  # type: ignore
+    email: EmailStr | None = Field(default=None, max_length=255)  # type: ignore    # ty: ignore[unused-ignore-comment]
     password: str | None = Field(default=None, min_length=8, max_length=128)
 
 
@@ -80,7 +80,7 @@ class ItemCreate(ItemBase):
 
 # Properties to receive on item update
 class ItemUpdate(ItemBase):
-    title: str | None = Field(default=None, min_length=1, max_length=255)  # type: ignore
+    title: str | None = Field(default=None, min_length=1, max_length=255)  # type: ignore   # ty: ignore[unused-ignore-comment]
 
 
 # Database model, database table inferred from class name
diff --git a/backend/app/utils.py b/backend/app/utils.py
index ac029f6342..03a0c16891 100644
--- a/backend/app/utils.py
+++ b/backend/app/utils.py
@@ -4,7 +4,7 @@
 from pathlib import Path
 from typing import Any
 
-import emails  # type: ignore
+import emails  # type: ignore    # ty: ignore[unused-ignore-comment]
 import jwt
 from jinja2 import Template
 from jwt.exceptions import InvalidTokenError
diff --git a/backend/pyproject.toml b/backend/pyproject.toml
index 66b4d66683..89a5bdd74e 100644
--- a/backend/pyproject.toml
+++ b/backend/pyproject.toml
@@ -25,6 +25,7 @@ dependencies = [
 dev = [
     "pytest<8.0.0,>=7.4.3",
     "mypy<2.0.0,>=1.8.0",
+    "ty>=0.0.25",
     "ruff<1.0.0,>=0.2.2",
     "prek>=0.2.24,<1.0.0",
     "coverage<8.0.0,>=7.4.3",
@@ -75,3 +76,6 @@ sort = "-Cover"
 
 [tool.coverage.html]
 show_contexts = true
+
+[tool.ty.terminal]
+error-on-warning = true
diff --git a/backend/scripts/lint.sh b/backend/scripts/lint.sh
index b3b2b4ecc7..ccc981e490 100644
--- a/backend/scripts/lint.sh
+++ b/backend/scripts/lint.sh
@@ -4,5 +4,6 @@ set -e
 set -x
 
 mypy app
+ty check app
 ruff check app
 ruff format app --check
diff --git a/uv.lock b/uv.lock
index aef1e5bb8d..312035345c 100644
--- a/uv.lock
+++ b/uv.lock
@@ -87,6 +87,7 @@ dev = [
     { name = "prek" },
     { name = "pytest" },
     { name = "ruff" },
+    { name = "ty" },
 ]
 
 [package.metadata]
@@ -115,6 +116,7 @@ dev = [
     { name = "prek", specifier = ">=0.2.24,<1.0.0" },
     { name = "pytest", specifier = ">=7.4.3,<8.0.0" },
     { name = "ruff", specifier = ">=0.2.2,<1.0.0" },
+    { name = "ty", specifier = ">=0.0.25" },
 ]
 
 [[package]]
@@ -2169,6 +2171,30 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/23/d1/136eb2cb77520a31e1f64cbae9d33ec6df0d78bdf4160398e86eec8a8754/tomli-2.4.0-py3-none-any.whl", hash = "sha256:1f776e7d669ebceb01dee46484485f43a4048746235e683bcdffacdf1fb4785a", size = 14477, upload-time = "2026-01-11T11:22:37.446Z" },
 ]
 
+[[package]]
+name = "ty"
+version = "0.0.26"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/18/94/4879b81f8681117ccaf31544579304f6dc2ddcc0c67f872afb35869643a2/ty-0.0.26.tar.gz", hash = "sha256:0496b62405d62de7b954d6d677dc1cc5d3046197215d7a0a7fef37745d7b6d29", size = 5393643, upload-time = "2026-03-26T16:27:11.067Z" }
+wheels = [
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+]
+
 [[package]]
 name = "typer"
 version = "0.21.1"