FastAPI code review, security audit, and deployment services
FastAPI is the fastest-growing Python framework for APIs, and it's what most AI tools reach for when building backend services, especially AI wrappers and data pipelines. Cursor and Claude Code frequently generate FastAPI projects - but vibe coded FastAPI apps often mix async and sync code incorrectly, skip input validation, and ship without proper authentication.
Common FastAPI issues we find
Real problems from FastAPI codebases we've reviewed.
Blocking calls inside async endpoints
Synchronous database calls, file operations, or HTTP requests inside async def endpoints block the entire event loop, making your API unresponsive under load.
Missing authentication on endpoints
API routes that handle sensitive data or actions without any auth middleware - Depends() for authentication is simply not included in the route definition.
No CORS configuration
CORSMiddleware either missing (blocking all cross-origin requests) or set to allow_origins=['*'] (allowing any website to call your API).
Pydantic models without validation constraints
Request models that accept any string length, any number range, and any format. No Field() constraints, so invalid data flows through your system.
Uvicorn dev server in production
Running uvicorn with --reload flag in production, or using a single worker. This means one crash or slow request brings down the whole API.
Missing error handling middleware
Unhandled exceptions return raw 500 errors with stack traces to clients, leaking internal code structure and potentially sensitive information.
No rate limiting on public endpoints
Public API endpoints (especially AI wrapper endpoints that call OpenAI or similar) have no rate limiting, so a single user can run up massive costs.
Database connections not pooled
Creating a new database connection on every request instead of using a connection pool, causing connection exhaustion under load.
FastAPI production checklist
Key checks before deploying your FastAPI app.
Async endpoints only call async functions (no blocking I/O)
Authentication dependency on all protected routes
CORS configured for specific origins (not wildcard)
Pydantic models have Field() validation constraints
Uvicorn running with multiple workers behind a process manager
Global exception handler returns safe error responses
Rate limiting on public and expensive endpoints
Database connection pooling configured (SQLAlchemy or similar)
Health check endpoint for monitoring and load balancers
OpenAPI docs disabled or protected in production
Not sure if your app passes? Our code audit checks all of these and more.
Our FastAPI services
Security Review
Manual security analysis of your application covering API endpoints, authentication, data access, and infrastructure configuration.
Deploy & Ship
From local development to production deployment.
Performance
Identify and fix performance bottlenecks, from slow page loads and unoptimized queries to missing caching.
Infrastructure
Databases, APIs, auth systems, email, file storage, and the backend services your application needs.
AI tools that generate FastAPI code
Our services
Get a professional review of your FastAPI project.
Security Review
Security Review
Expert engineer works on your project directly. Fixed scope, fixed price, no surprises.
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Full Pentest
Enterprise-grade engagement tailored to your needs. Dedicated engineer, ongoing support.
Fix Bugs
Bug Fixing
Expert engineer works on your project directly. Fixed scope, fixed price, no surprises.
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Ongoing Support
Enterprise-grade engagement tailored to your needs. Dedicated engineer, ongoing support.
Refactor Code
Refactoring
Expert engineer works on your project directly. Fixed scope, fixed price, no surprises.
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Full Rewrite
Enterprise-grade engagement tailored to your needs. Dedicated engineer, ongoing support.
All projects start with a free consultation. We scope your project and provide a fixed quote before any work begins.
How it works
Tell us about your app
Share your project details and what you need help with.
Get a clear quote
We respond within 24 hours with scope, timeline, and a fixed price.
Launch with confidence
We get to work, deliver results, and stick around to help.
Frequently asked questions
Is my AI-generated FastAPI backend production-ready?
Almost certainly not. AI tools get the basic routes right but miss async correctness, authentication, rate limiting, and production server configuration. We review and fix all of these before launch.
How do I deploy a FastAPI app properly?
We deploy FastAPI with Uvicorn behind Gunicorn with multiple workers, configure connection pooling, set up health checks, and add monitoring. We deploy to Railway, Render, AWS, or Docker-based platforms.
Can you add authentication to my FastAPI project?
Yes. We implement JWT or OAuth2 authentication with proper dependency injection, token refresh, role-based access control, and secure session handling.
Related resources
Need help with your FastAPI project?
Tell us about your project. We'll respond within 24 hours with a clear plan and fixed quote.