Custom API Integration Services Built for Performance, Security & Scale
Your CRM doesn't talk to your billing system. Your mobile app fetches data through a different backend than your web dashboard. Your partner integration breaks every time they update their API because nobody versioned yours. And every time your engineering team needs to connect a new service, it takes six weeks of custom plumbing instead of six hours. These aren't rare problems — they're the predictable result of building without an API strategy.
As a custom api development company with 150+ APIs designed, built, and deployed across REST, GraphQL, and webhook architectures, Dcrayons builds the integration layer that makes your entire technology stack work as one system. Our api development and integration services have delivered sub-50ms average response times under production load, 99.99% uptime across all managed API infrastructure, and integration timelines that drop from weeks to days through well-documented, versioned endpoints with Swagger/OpenAPI specifications.
Every custom api integration services project starts with an integration audit: we map your current data flows, identify bottlenecks and single points of failure, define authentication and authorization requirements (OAuth 2.0, JWT, API keys), plan rate limiting and throttling strategies, and produce an API architecture specification with endpoint documentation before writing a single line of code.
Our API Development Process: From Integration Audit to Production Deployment
A six-phase methodology that eliminates the three biggest API failures — breaking changes, performance degradation under load, and security vulnerabilities in authentication flows.
Integration Audit & Architecture Design
1-2 week deep-dive: current data flow mapping across all systems, bottleneck identification, authentication and authorization audit, rate limiting requirements, and API consumer analysis. The output: an OpenAPI specification with endpoint definitions, data models, authentication flows, and versioning strategy — everyone agrees on the contract before development begins.
API Design & Contract Definition
RESTful resource modeling or GraphQL schema design following industry best practices: consistent naming conventions, proper HTTP status codes, pagination strategies, filtering and sorting parameters, and HATEOAS links where appropriate. Swagger/OpenAPI 3.0 specification generated and shared with all consumers for parallel frontend and mobile development — no waiting for backend completion.
Backend Development & Data Layer
Node.js (Express/Fastify), .NET (ASP.NET Core), or Python (FastAPI/Django REST) backend with PostgreSQL, SQL Server, or MongoDB. Connection pooling, query optimization, and caching layers (Redis) that deliver sub-50ms response times. Database migrations managed through versioned schema changes. Every API endpoint includes input validation, error handling, and structured logging for debugging.
Authentication, Security & Rate Limiting
OAuth 2.0 authorization flows (authorization code, client credentials, PKCE for SPAs), JWT token management with refresh rotation, API key generation and automated rotation, IP allowlisting, and rate limiting per consumer tier. Input sanitization against injection attacks. OWASP API Security Top 10 compliance. Penetration testing of all authentication endpoints before production deployment.
Testing, Load Testing & Documentation
Automated testing pyramid: unit tests for business logic, integration tests for database operations, and contract tests validating API responses against OpenAPI specs. Load testing with k6 simulating 10x expected peak traffic. Interactive API documentation via Swagger UI and Redoc. Postman collections with example requests for every endpoint — ready for consumer teams to import and start integrating immediately.
Deployment, Monitoring & Versioning
AWS API Gateway or custom reverse proxy deployment with auto-scaling, blue-green releases, and canary routing. Real-time monitoring via Datadog APM tracking response times, error rates, and throughput per endpoint. Semantic versioning (v1, v2) with deprecation notices and sunset timelines. Webhook delivery monitoring with automatic retry and dead-letter queues. Post-launch: 99.99% uptime SLA with 15-minute incident response.
API Performance From 150+ Production Integrations
Production metrics measured through Datadog APM, New Relic, and custom monitoring — not Postman test results or staging benchmarks.
150+ APIs Deployed. Sub-50ms Response. 99.99% Uptime.
Backend engineers averaging 8+ years building production APIs. Node.js, .NET, and Python specialists with AWS API Gateway, GraphQL Federation, and microservices architecture expertise.
< 50ms
Average API Response Time Under Production Load
What CTOs and Engineering Leads Say About Our API Development
APIs That Scale. Integrations That Last.
Services That Complement Your API Development Project
A well-architected API layer delivers maximum value when supported by these services that build the applications and infrastructure consuming your APIs.
Digital Marketing
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Technology
Our internet marketing company goes beyond surface-level SEO. We combine AI-powered automation with white-hat SEO practices to help you achieve higher organic rankings and ensure your brand remains visible in AI search results.
Creative & Strategy
Our internet marketing company goes beyond surface-level SEO. We combine AI-powered automation with white-hat SEO practices to help you achieve higher organic rankings and ensure your brand remains visible in AI search results.
Our API Development Technology Stack
REST. GraphQL. Webhooks. Production-Proven.
REST API & OpenAPI Standards
RESTful API design following Richardson Maturity Model with proper resource naming, HTTP methods, status codes, and pagination.
OpenAPI 3.0 specifications generated from code annotations for always-accurate documentation. Swagger UI and Redoc for interactive API exploration. Our rest api development services deliver APIs that external teams can integrate with in hours, not weeks.
GraphQL & Federation
Apollo Server or Hasura GraphQL with schema-first design, type safety, and resolver optimization.
GraphQL Federation for microservices architectures where multiple teams own different subgraphs. Dataloader pattern for N+1 query prevention. Ideal for mobile apps and dashboards that need flexible data fetching without over-fetching — reducing payload sizes by 40-60% compared to REST.
Node.js, .NET & Python Backends
Express/Fastify (Node.js) for high-throughput event-driven APIs, ASP.NET Core (.NET) for enterprise-grade APIs with strong typing and dependency injection, FastAPI (Python) for ML/AI-integrated endpoints.
PostgreSQL, SQL Server, MongoDB, and Redis for data persistence and caching. Each technology chosen based on your team's expertise and your application's performance requirements.
AWS API Gateway & Infrastructure
AWS API Gateway for managed API hosting with throttling, caching, and WAF protection.
Lambda for serverless API endpoints that scale to zero. CloudWatch and Datadog APM for real-time monitoring. GitHub Actions CI/CD with automated OpenAPI validation, contract testing, and staged rollouts. Terraform infrastructure-as-code for reproducible API environments across dev, staging, and production.
The Dcrayons API Development Difference
Why 76% of Clients Return for More Integrations
Sub-50ms Response Times — Production performance, not Postman benchmarks. Caching, connection pooling, and query optimization deliver speed at scale.
API-First Documentation — OpenAPI specs, Swagger UI, and Postman collections. Your consumers integrate in hours, not weeks of reverse-engineering.
Security by Design — OAuth 2.0, JWT rotation, rate limiting, and OWASP API Top 10 compliance. Zero authentication breaches across all clients.
76% Come Back — Most agencies build and leave. 76% of our API clients return for additional integrations and microservices expansion.
Most agencies build APIs that work in Postman. We build APIs that work under 10,000 concurrent requests at 3 AM when your partner's batch job hits your endpoints and your monitoring needs to catch the 0.1% of requests that exceed SLA. That level of production-readiness starts with understanding your data model, your consumer patterns, and your scaling trajectory before designing a single endpoint.
It's also why 76% of our API clients return for additional integrations. When your business acquires a company with a different tech stack, when your mobile app needs real-time WebSocket connections, or when your enterprise clients demand a bespoke api integration with their procurement system — you call the custom api development company that already understands your data architecture and authentication infrastructure. That continuity eliminates months of reverse-engineering and prevents the integration conflicts that plague agency switches.
API Development FAQs
Simple REST APIs (CRUD operations, authentication, 10-20 endpoints): $10,000-$30,000. Complex integration APIs (multiple third-party systems, real-time sync, webhook infrastructure): $30,000-$80,000. Enterprise API platforms (microservices architecture, GraphQL federation, API gateway): $80,000-$200,000+. We provide fixed-price quotes after a 1-2 week integration audit — no hourly billing surprises.
REST for standard CRUD operations with predictable data shapes and strong caching requirements. GraphQL for mobile apps and dashboards that need flexible data fetching, where different screens need different subsets of the same data. Many projects benefit from both: REST for external partner APIs (simpler to consume) and GraphQL for internal frontend consumption. Our audit evaluates your specific consumer patterns to recommend the right approach.
Simple REST APIs (10-20 endpoints): 4-8 weeks. Complex integration platforms (50+ endpoints, multiple third-party connections): 10-16 weeks. Microservices migration from monolith: 16-24 weeks (phased). We deliver in 2-week sprints with working endpoints at every milestone — your frontend team can start integrating from sprint 2, not waiting until the API is 'finished.'
Semantic versioning (v1, v2) with URL-based or header-based version routing. Breaking changes only in major versions with minimum 6-month deprecation notices and sunset timelines. Non-breaking additions (new fields, new endpoints) ship without version bumps. Automated contract testing catches accidental breaking changes before they reach production. Your consumers never wake up to a broken integration.
Defense-in-depth: OAuth 2.0 authorization with PKCE for SPAs, JWT tokens with automated refresh rotation, API key management with per-consumer rate limits, IP allowlisting for server-to-server integrations, input validation against injection attacks, and WAF protection at the API gateway layer. Every API passes OWASP API Security Top 10 review and penetration testing before production deployment.
Yes. Managed API packages ($2,000+/month) include real-time APM monitoring (Datadog/New Relic), error rate alerting with PagerDuty escalation, performance regression detection, uptime monitoring with 99.99% SLA, dependency update management, and a dedicated Slack channel. We also provide consumer support — helping your partners and internal teams integrate with your API through documentation updates and debugging assistance.