You will get I will build fast, scalable REST APIs with FastAPI
Project details
I’m a Senior Backend Engineer with 15+ years of experience building clean, scalable REST APIs using FastAPI.
I help startups and teams design and implement production-ready APIs that are fast, secure, and easy to maintain. Whether you need a new backend service, internal API, or feature expansion, I deliver reliable FastAPI solutions built the right way.
I can help you with:
• REST API design and endpoint implementation
• Request validation and error handling
• Authentication and authorization (JWT, OAuth)
• PostgreSQL database integration
• Async endpoints and background tasks
• API documentation (OpenAPI / Swagger)
• Deployment-ready FastAPI services
How I work:
1. Review requirements and define API scope
2. Design clean endpoints and data models
3. Implement secure, scalable FastAPI code
4. Test endpoints and edge cases
5. Deliver documented, production-ready APIs
This service is ideal for new projects, internal tools, or extending existing backends with new API functionality.
I help startups and teams design and implement production-ready APIs that are fast, secure, and easy to maintain. Whether you need a new backend service, internal API, or feature expansion, I deliver reliable FastAPI solutions built the right way.
I can help you with:
• REST API design and endpoint implementation
• Request validation and error handling
• Authentication and authorization (JWT, OAuth)
• PostgreSQL database integration
• Async endpoints and background tasks
• API documentation (OpenAPI / Swagger)
• Deployment-ready FastAPI services
How I work:
1. Review requirements and define API scope
2. Design clean endpoints and data models
3. Implement secure, scalable FastAPI code
4. Test endpoints and edge cases
5. Deliver documented, production-ready APIs
This service is ideal for new projects, internal tools, or extending existing backends with new API functionality.
Programming Languages
JavaScript, Python, TypeScriptCoding Expertise
Performance Optimization, SecurityWhat's included
| Service Tiers |
Starter
$60
|
Standard
$150
|
Advanced
$350
|
|---|---|---|---|
| Delivery Time | 2 days | 4 days | 7 days |
Number of Revisions | 1 | 2 | 3 |
Number of Pages | 0 | 0 | 0 |
Design Customization | - | - | - |
Content Upload | - | - | - |
Responsive Design | - | - | - |
Source Code | - | - | - |
Optional add-ons
You can add these on the next page.
Fast Delivery
+$40 - $120
Additional Endpoint
(+ 1 Day)
+$50Frequently asked questions
About Cosmel
Senior Backend Engineer | FastAPI, Django, Rails, Node | API Debugging
Tres Rios, Costa Rica - 1:00 pm local time
I specialize in Python (FastAPI, Django), Ruby on Rails, Node.js, PostgreSQL, and AWS, with deep expertise in API design, debugging, backend optimization, and serverless/cloud deployments.
Clients hire me to:
• Fix backend bugs, performance issues, failing endpoints, and 500 errors
• Diagnose and resolve API issues in FastAPI, Django, Rails, or Node
• Build secure, scalable REST and GraphQL APIs from scratch
• Improve database performance and eliminate bottlenecks (PostgreSQL, Redis)
• Modernize backend systems and migrate workloads to AWS (Lambda, API Gateway, S3, RDS)
• Develop automation, background workers, and distributed systems
• Add new backend features, integrations, and complex logic
Why technical teams trust me:
• I identify root causes quickly and fix them cleanly
• I understand real-world production systems and edge cases
• I write maintainable, well-tested code that survives scale
• I communicate clearly, give proactive updates, and deliver on time
• I reduce risk — no breaking changes, no surprises
Why Work With Me
• 15+ years experience across backend, APIs, architecture, and debugging
• Production-grade solutions, not “quick patches”
• Clear communication and expectations
• Strong ownership and delivery on deadlines
• Experience working with U.S. companies and distributed teams
• Ability to quickly understand existing systems and ship reliable results
Tech Stack
Python, FastAPI, Django, Node.js, TypeScript, Ruby on Rails
PostgreSQL, Redis
AWS Lambda, API Gateway, S3, RDS, CloudFront
REST, GraphQL, CI/CD, Docker
If you need a backend engineer who can take ownership, solve difficult problems, and deliver production-ready APIs and backend systems — let’s talk.
Steps for completing your project
After purchasing the project, send requirements so Cosmel can start the project.
Delivery time starts when Cosmel receives requirements from you.
Cosmel works on your project following the steps below.
Revisions may occur after the delivery date.
Analyze requirements
I will review your specifications, confirm all endpoints, data models, and dependencies, and ensure we have a complete, accurate API plan.
Build the FastAPI endpoints
I will implement all requested API routes with proper validation, error handling, authentication (if required), and clean, maintainable code.