FastAPI Schema Diff.
Compare Alembic migrations.
Zero setup.

Alembic Migration Review

Compare alembic revision --autogenerate outputs before and after model changes. Verify that SQLAlchemy migrations produced exactly the schema you expected.

SQLModel & Pydantic Sync

Diff schemas generated from SQLModel tables with Pydantic-validated columns. Detects Optional[int] → int nullability changes and Field default modifications.

SQLAlchemy Column Changes

Detects String(50) → Text(), Integer → BigInteger, and Enum value changes. Warns when length reductions could truncate data.

Relationship & Foreign Key

Validates relationship() and ForeignKey constraints. Detects missing or changed foreign keys that could break FastAPI's dependency-injected database sessions.

Enum & Check Constraint

Compares PostgreSQL ENUM types and CheckConstraint declarations. Catches schema drift that breaks Pydantic model validation or OpenAPI schema generation.

Privacy First

Your schema never leaves the browser. Compare production FastAPI schemas safely without uploading sensitive table structures to a third-party server.

Add a new column

ALTER TABLE users
  ADD COLUMN is_active BOOLEAN DEFAULT TRUE;

Extend enum values

ALTER TYPE status_enum ADD VALUE 'archived';
ALTER TABLE posts
  ALTER COLUMN status TYPE status_enum;

Add a foreign key

ALTER TABLE comments
  ADD CONSTRAINT comments_post_id_fkey
  FOREIGN KEY (post_id) REFERENCES posts(id)
  ON DELETE CASCADE;

Add a check constraint

ALTER TABLE products
  ADD CONSTRAINT chk_price_positive
  CHECK (price >= 0);