Building a api / backend service with FastAPI? Let us review it.
Expert code review for api / backend services built with FastAPI. We fix FastAPI-specific security gaps, optimize performance, and handle deployment. From $19.
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.
API / Backend Service challenges to solve
Key api / backend service concerns that AI-generated code often misses.
Authentication and API keys
Every endpoint needs to verify the caller's identity. AI tools create endpoints without auth, or with auth that's easy to bypass. You need token-based auth, API key management, and proper session handling.
Input validation
Every parameter, request body, and header value must be validated before use. AI-generated APIs trust client data, which leads to injection attacks, data corruption, and crashes from unexpected input.
Rate limiting and abuse prevention
Without rate limits, anyone can hammer your API — brute-forcing passwords, scraping data, or running up your infrastructure costs. Rate limiting must be per-user and per-endpoint.
Error handling and status codes
APIs should return appropriate HTTP status codes (400 for bad input, 401 for unauthorized, 404 for not found, 500 for server errors) with helpful error messages. AI tools often return 200 for everything or expose internal error details.
What we check
Key areas we review for FastAPI api / backend service projects.
Authentication on every endpoint — no unprotected routes
Input validation — every parameter validated with schema
Rate limiting — per-user, per-endpoint limits configured
Error responses — correct status codes, no internal detail leaks
Not sure if your app passes? Our code audit ($19) checks all of these and more.
Start with a self-serve audit
Get a professional review of your FastAPI api / backend service project at a fixed price.
External Security Scan
Black-box review of your public-facing app. No code access needed.
- OWASP Top 10 vulnerability check
- SSL/TLS configuration analysis
- Security header assessment
- Expert review within 24h
Code Audit
In-depth review of your source code for security, quality, and best practices.
- Security vulnerability analysis
- Code quality review
- Dependency audit
- Architecture review
- Expert + AI code analysis
Complete Bundle
Both scans in one package with cross-referenced findings.
- Everything in both products
- Cross-referenced findings
- Unified action plan
100% credited toward any paid service. Start with an audit, then let us fix what we find.
How it works
Tell us about your app
Share your project details and what you need help with.
Expert + AI audit
A human expert assisted by AI reviews your code within 24 hours.
Launch with confidence
We fix what needs fixing and stick around to help.
Frequently asked questions
Can you review a api / backend service built with FastAPI?
Yes. We regularly audit FastAPI api / backend service projects and understand the specific patterns and pitfalls of this combination. Our review covers security, performance, and deployment readiness.
What issues do you find in FastAPI api / backend services?
Common issues include blocking calls inside async endpoints and missing authentication on endpoints on the FastAPI side, combined with api / backend service-specific concerns like authentication and api keys and input validation. We check for all of these and more.
How do I make my FastAPI api / backend service production-ready?
Start with our code audit ($19) to get a prioritized list of issues. For FastAPI api / backend service projects, the typical path is: fix security gaps, address api / backend service-specific requirements, optimize FastAPI performance, then configure deployment. We provide a fixed quote after the audit.
How long does it take to audit a FastAPI api / backend service?
Our code audit delivers a full report within 24 hours. For FastAPI api / backend service projects, we check security, architecture, performance, and deployment readiness across all FastAPI-specific patterns. Fixes are scoped separately with a fixed quote.
Related resources
FastAPI by Use Case
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