Does Flask Work With SQLite?
Flask and SQLite work together seamlessly and are one of the most popular lightweight combinations for Python web applications.
Quick Facts
How Flask Works With SQLite
Flask doesn't include built-in database support, but integrating SQLite is straightforward using Flask-SQLAlchemy, which wraps SQLAlchemy's ORM. SQLite is ideal for Flask because it requires no separate server—the database is just a file on your filesystem, making it perfect for development, prototyping, and small-to-medium production applications. The developer experience is excellent: you define models as Python classes, Flask-SQLAlchemy handles connection pooling and teardown automatically, and migrations are managed with Flask-Migrate (Alembic). For larger applications expecting high concurrency, PostgreSQL might be better, but SQLite handles thousands of requests fine for most use cases. The combination is popular because it eliminates DevOps complexity—no database server to manage, easy to version control, and ideal for embedded analytics or offline-capable applications.
Best Use Cases
Quick Setup
pip install flask flask-sqlalchemyfrom flask import Flask
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
db = SQLAlchemy(app)
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(80), unique=True, nullable=False)
email = db.Column(db.String(120), unique=True, nullable=False)
@app.route('/users', methods=['POST'])
def create_user():
user = User(username='john', email='john@example.com')
db.session.add(user)
db.session.commit()
return {'id': user.id}
if __name__ == '__main__':
with app.app_context():
db.create_all()
app.run()Known Issues & Gotchas
SQLite doesn't handle high write concurrency well—multiple simultaneous writes can cause 'database is locked' errors
Fix: Use connection timeout settings (timeout parameter) and implement retry logic for writes, or migrate to PostgreSQL for production if concurrency becomes an issue
SQLite locks the entire database during writes, not individual tables or rows
Fix: Keep transactions short and minimize write frequency; consider batch operations
Schema migrations can be risky with SQLite due to limited ALTER TABLE support
Fix: Use Flask-Migrate/Alembic for all migrations; test locally first
SQLite doesn't enforce many constraints by default (like foreign keys)
Fix: Enable foreign keys with PRAGMA in your Flask config: db.engine.execute('PRAGMA foreign_keys=ON')
Alternatives
- •Flask + PostgreSQL: Better concurrency and features for production applications
- •Django + SQLite: Full-featured framework with built-in ORM and admin panel
- •FastAPI + SQLAlchemy + SQLite: Modern async alternative with higher performance potential
Resources
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