Custom API Development Services

Choose custom when your business logic doesn't map cleanly to a generic platform, when you need a long-lived contract you can version yourself, when authentication and authorisation rules are non-standard, or when integration with your existing systems is going to require sustained engineering effort either way. Stick with off-the-shelf when the platform genuinely covers your use case and the vendor's roadmap is heading where you need to go.

REST is the right choice for predictable resource models, public APIs, and integrations where HTTP semantics and caching matter — particularly when partners or third parties consume the API. GraphQL is the right choice when frontend teams need flexible queries that reduce over-fetching, or when a single API serves multiple frontends with different data requirements. We help you pick during scoping based on consumer profile rather than defaulting to one out of preference.

Yes. We frequently extend or sit alongside existing stacks — Node, Python, Ruby, PHP, .NET, or whatever your business runs. The integration can take the form of adding APIs in front of legacy systems (the strangler-fig pattern), exposing endpoints over an existing database, or providing fresh APIs that integrate with your existing CRM, ERP, or third-party platforms.

Node.js with TypeScript is our default — it gives us full-stack consistency with our frontend work and a mature ecosystem of well-maintained libraries. We also build in Python, Go, and use Next.js Route Handlers for full-stack setups where the API and frontend share a deploy unit. Database choice (PostgreSQL, MySQL, MongoDB) is driven by access patterns alongside our database design team.

Authentication is built around the consumer profile. OAuth 2.0 with refresh-token rotation for public APIs and partner integrations; JWT for internal service-to-service traffic; API keys with scoped permissions for machine-to-machine; session-based auth where it suits the deployment. Authorisation is implemented as role-based or attribute-based access control with the rules expressed once rather than scattered across endpoints — and audit logging is configured by default for any system that will face a security review.

Yes. Every API ships with an OpenAPI or GraphQL schema, developer-facing documentation with worked examples, a Postman collection for quick experimentation, and architecture documentation covering deployment, scaling, and incident response. Documentation is generated from the schema during the build so it stays current rather than drifting over time.

Yes. We deploy to AWS, Vercel, DigitalOcean, or your preferred provider with proper CI/CD, staging environments, and observability tooling configured during deployment. Ongoing hosting, monitoring, patching, and incident response are available on retainer via our managed UK hosting and API testing and monitoring services.

Versioning policy is agreed at the contract design stage — usually via URL path versioning for REST (e.g. /v1/) or schema directives for GraphQL. Breaking changes go through a documented deprecation process with timelines and migration guidance so consumers can adapt without surprises. We are explicit about which changes are breaking versus additive so you can evolve the API safely as your product grows.

You receive a full handover — codebase, documentation, deployment artefacts, runbooks, and a walkthrough with your team if you have one. From there, we are available on retainer for ongoing maintenance, feature evolution, and operational support — or fully handed off to your internal team with the documentation needed to take it forward independently.