RESTful API Development
Production-grade REST APIs in Node.js, Python, and .NET with OpenAPI 3.0 specs, versioning, and consistent error contracts. Every endpoint ships with automated tests and p95 latency targets under 200ms.
Web App
API Development
Robust APIs that power your apps, partners, and integrations.
We design RESTful and GraphQL APIs with proper versioning, authentication, rate limiting, and documentation — built for developers and scale.
Our Offerings
API Development Services We Provide
GraphQL API Development
Apollo and Relay-compatible GraphQL layers that let front-end teams fetch exactly the data they need in one round trip. We implement persisted queries, dataloader batching, and depth limiting to keep performance predictable.
Third-Party API Integration
We connect your systems to Stripe, Salesforce, QuickBooks, Twilio, shipping carriers, and 200+ other services with retry logic and webhook handling. Integrations include sandbox testing and monitoring so failures never go unnoticed.
API Gateway & Microservices
Kong, AWS API Gateway, and Azure APIM setups with rate limiting, authentication, and request transformation at the edge. We decompose monoliths into microservices incrementally, without big-bang rewrites.
API Security & Compliance
OAuth 2.0, JWT, mTLS, and scope-based authorization implemented to OWASP API Security Top 10 standards. For regulated clients we deliver HIPAA-compliant and PCI DSS-aligned API architectures with full audit logging.
API Documentation & Developer Portals
Interactive Swagger/Redoc documentation, Postman collections, and self-serve developer portals with API key management. Good docs cut partner onboarding from weeks to days.
What We Deliver
End-to-End API Development
- REST & GraphQL design
- OAuth & JWT auth
- Rate limiting
- OpenAPI documentation
- Webhook support
- API gateway setup
Why Choose Devlex
Business Outcomes That Matter
✓Enable partner ecosystems
✓Faster frontend development
✓Secure data exchange
✓Future-proof integrations
Technologies
Tools & Stack We Use
We pick the right technology for your goals — not the trendiest framework.
- Node.js
- Python
- GraphQL
- Postman
- Kong
- AWS API Gateway
Our Approach
- Discover — Understand goals & constraints
- Design — Architecture & UX blueprint
- Build — Agile sprints with weekly demos
- Launch — Deploy, test & support
0Years of Experience
0Projects Delivered
0Global Clients
0In-house Experts
0Countries Served
0Code Ownership
How We Work
What You Get In Writing
Terms that go into every agreement we sign. See all client commitments.
A Written Price Before Work Starts
Every job gets a scope and a number in writing first — a fixed price for defined work, or an hourly rate with a capped estimate. If scope changes, we re-quote before we build, not after.
You Own the Code
Source code, designs, and data are yours. We work in your repository where possible, hand over full documentation, and transfer everything at the end. No license fees, no hostage situations.
NDA Before You Share Anything
We sign your NDA — or send ours — before the first technical conversation. Your idea, your data, and your customer information stay confidential during and after the engagement.
FAQ
API Development — FAQs
Everything you need to know before starting your project. Still have questions? Talk to our team.
REST, GraphQL, gRPC, and WebSocket APIs for mobile backends, partner integrations, internal microservices, and public developer platforms. We also build webhook systems and event-driven architectures on Kafka and AWS SQS/SNS.
A focused integration (connecting two systems) takes 2-4 weeks; a full custom API backend for a mobile or web product takes 2-4 months. Public APIs with developer portals and documentation typically run 3-5 months.
Single integrations start around $5,000-$12,000, custom API backends range $20,000-$60,000, and enterprise API platforms with gateways and portals run $60,000+. Hourly work starts at $12/hour for ongoing integration support.
You receive full ownership of all source code, OpenAPI specifications, infrastructure scripts, and documentation on final payment. Everything is delivered in your own Git and cloud accounts from day one if you prefer.
We instrument every API with monitoring (Datadog, CloudWatch, or Grafana), set alerting on error rates and latency, and offer 24/7 support with SLAs. Versioning policies ensure existing consumers never break when we ship new capabilities.
Yes — we design for horizontal scaling with load balancing, Redis caching, and database read replicas, and validate with load tests at 5-10x expected peak. Our APIs in production handle from a few thousand to 50 million+ requests per day.
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