Custom API engineering services
Custom API Engineering & Integration
Secure, documented REST and GraphQL APIs that connect your core software to the CRM, payment, marketplace, and ERP systems your business already runs on — built to be maintained, not just to work once.
Integrations built in a hurry become the next outage.
Every additional integration is another point of failure if it’s not engineered properly, undocumented endpoints, no rate limiting, no retry logic. Custom API engineering treats integrations as first-class infrastructure, not a quick script glued between two systems.
- Integrations that break silently with no error visibility
- Undocumented APIs only one engineer understands
- Rate limits or auth failures causing data sync gaps
- A patchwork of point-to-point connections nobody has mapped
What a custom API engagement covers
We build APIs and integrations the same way we build core product: documented, tested, and owned by you.
API design & specification
REST or GraphQL contracts defined upfront with an OpenAPI specification before implementation starts.
Secure implementation
Authentication, rate limiting, input validation, and audit logging built into every endpoint.
Third-party & legacy integration
Connectors for CRM, payment, marketplace, and ERP systems, including adapters for legacy backends.
Monitoring & documentation
Generated documentation and error monitoring so integrations stay maintainable long after launch.
Talk to a senior engineer before you commit to a build.
Free 15 minute discovery call. No account managers, no sales script.
How we engineer integrations that don’t become outages
Contract-first design
The API contract is defined and reviewed before a single endpoint is implemented.
Secure, tested build
Authentication, validation, and automated tests built in from the first commit.
Sandbox integration testing
Every third-party connection is tested against sandbox credentials before going live.
Documented handoff
Generated API documentation and monitoring dashboards handed over with the code.
Why API integration services need engineering ownership, not just a connector
Most API integration platforms on the market solve the easy 80% of a connection and leave founders to debug the hard 20% themselves. Custom API engineering exists for that remaining 20%: the edge cases, rate limits, and data model mismatches that a generic connector was never built to handle. REST API development services done properly treat every integration as production infrastructure, not a temporary bridge.
As more B2B API integration services move toward event-driven architectures, an enterprise API connector development partner needs to be fluent in both REST and GraphQL API engineering, not just one. Third party API integration work increasingly requires secure API gateway development as a baseline, not an add-on — a custom API integration company that treats security as an afterthought is building your next incident, not preventing it.
Trusted by founders and technical leaders
Our marketplace sync used to fail silently once a week. It’s been fully stable since they rebuilt the integration layer.
They documented every endpoint so well that our own team could take over maintenance without a handoff call.
The API gateway they built has handled every rate-limit spike from our partners without a single dropped request.
Our marketplace sync used to fail silently once a week. It’s been fully stable since they rebuilt the integration layer.
They documented every endpoint so well that our own team could take over maintenance without a handoff call.
The API gateway they built has handled every rate-limit spike from our partners without a single dropped request.
Questions US founders ask about this service
Define the resource model and contract first, build against an OpenAPI specification, then implement with automated tests and generated documentation so the API stays accurate as it evolves.
Through OAuth2 or API-key authentication, strict rate limiting, input validation at every endpoint, encrypted transport, and audit logging of every request touching sensitive data.
By building an adapter layer that translates between the legacy system’s data model and a modern API contract, so the legacy backend doesn’t need to be rewritten to participate in new integrations.
Consistent error response formats, exponential backoff on retries, circuit breakers for failing dependencies, and clear rate-limit headers so consuming systems can self-throttle instead of failing silently.
API integrations touch your most sensitive data flows. A partner with direct engineering ownership, US-based accountability, and a sandbox-first process reduces the risk of a broken integration taking down production systems.