What is Flask-Migrate?

Flask-Migrate is a Flask extension that handles SQLAlchemy database schema migrations using Alembic. Without migrations, db.create_all() only creates new tables but does not modify existing ones — you cannot add columns or change types without dropping and recreating tables. Flask-Migrate tracks schema changes as migration scripts. Commands: flask db init (initialize migration folder). flask db migrate -m "Add phone column" (auto-generate migration from model changes). flask db upgrade (apply pending migrations). flask db downgrade (roll back last migration). Migration scripts are Python files stored in the migrations/ folder and should be committed to version control. Always review auto-generated migrations — Alembic may not detect all changes (e.g., column renames) and may generate incorrect migration SQL.