You will get I will build secure REST or GraphQL APIs using Django, FastAPI, or Node.js
Project details
I’m a Senior Backend Engineer with 15+ years of experience building secure, production-ready APIs for web and mobile applications.
If you need a REST or GraphQL API and don’t want to worry about framework choices, architecture, or security details, I can design and build a clean backend using Django, FastAPI, or Node.js — based on what best fits your needs.
I help clients build APIs that are reliable, maintainable, and easy to extend. This includes authentication, business logic, database integration, and clear API contracts for frontend or mobile teams.
I can help you with:
• REST or GraphQL API design and implementation
• Authentication and authorization (JWT, OAuth)
• PostgreSQL or MySQL database integration
• Business logic and data validation
• APIs for React, mobile apps, or third-party integrations
• Secure, production-ready backend services
How I work:
1. Review requirements and define API scope
2. Design clean endpoints and data models
3. Implement secure backend logic
4. Test endpoints and edge cases
5. Deliver clean, maintainable API code
This service is ideal for startups, internal tools, or teams needing a reliable backend API without framework lock-in.
If you need a REST or GraphQL API and don’t want to worry about framework choices, architecture, or security details, I can design and build a clean backend using Django, FastAPI, or Node.js — based on what best fits your needs.
I help clients build APIs that are reliable, maintainable, and easy to extend. This includes authentication, business logic, database integration, and clear API contracts for frontend or mobile teams.
I can help you with:
• REST or GraphQL API design and implementation
• Authentication and authorization (JWT, OAuth)
• PostgreSQL or MySQL database integration
• Business logic and data validation
• APIs for React, mobile apps, or third-party integrations
• Secure, production-ready backend services
How I work:
1. Review requirements and define API scope
2. Design clean endpoints and data models
3. Implement secure backend logic
4. Test endpoints and edge cases
5. Deliver clean, maintainable API code
This service is ideal for startups, internal tools, or teams needing a reliable backend API without framework lock-in.
Programming Languages
JavaScript, Python, TypeScriptCoding Expertise
Cross Browser & Device Compatibility, 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
API documentation
(+ 1 Day)
+$50Frequently asked questions
About Cosmel
Senior Backend Engineer | FastAPI, Django, Rails, Node | API Debugging
Tres Rios, Costa Rica - 1:17 am 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.
Review requirements & confirm API architecture
I will review your requirements, clarify any questions, and define the API architecture — including database schema, authentication flow, and endpoint structure.
Develop secure API endpoints
I will build the requested REST or GraphQL endpoints with clean, scalable code using Django, FastAPI, or Node.js. This includes request validation, authentication, and database integration.