API DevelopmentServices
Well-designed REST and GraphQL interfaces that let your apps, partners and systems share data reliably and securely.
API Development Services: what the work involves
An API is a promise to everyone who builds against it. Mobile apps, partner systems and your own web front end all depend on its shape staying predictable, its errors being readable and its security being sound. When APIs grow without a design, endpoints multiply, naming drifts, one client breaks when another is fixed, and nobody knows which fields are safe to change. A clean contract is what keeps a growing system from tying itself in knots.
DevKey designs APIs contract-first. We agree resources, naming, pagination, error formats and authentication before writing handlers, publish an OpenAPI or GraphQL schema as the source of truth, and generate documentation and typed clients from it. Rate limits, idempotency keys, input validation and structured logging are built in, and versioning rules allow you to evolve the interface without breaking existing consumers.
Core features
Contract-first design
Resources, fields and behaviours are specified in an OpenAPI or GraphQL schema reviewed with you before implementation begins.
Authentication and authorisation
API keys, OAuth or token-based sessions with scoped permissions, so each consumer can reach only what it should.
Validation and consistent errors
Inputs are validated at the boundary and failures return structured, documented errors that client developers can act on.
Versioning and deprecation policy
Changes are introduced without breaking existing clients, with versions, deprecation notices and a clear timeline for retirement.
Documentation and test sandbox
Interactive reference docs, example requests and a sandbox environment let integrators test without touching production data.
Rate limiting, logging and monitoring
Throttling, request tracing and dashboards show who is calling what, protect the backend and make incidents faster to diagnose.
What we get right before launch
Breaking the unknown consumer
Once an API is public, you cannot see every client. We treat field removal and meaning changes as breaking, add rather than alter, and watch usage by version before retiring anything.
REST or GraphQL
GraphQL suits varied client needs, while REST is simpler to cache and to hand to partners. We recommend based on who will consume the API, and can offer both over the same services.
Idempotency and retries
Networks fail and clients retry. For payments and orders we accept idempotency keys so a repeated request creates one result, not two charges.
Tools and technology
- Node.js
- TypeScript
- REST
- GraphQL
- PostgreSQL
- Prisma
- Redis
- Docker
- Message queues
Common questions, answered
Should we choose REST or GraphQL?
REST is simple, widely understood and easy to cache, which suits partner integrations. GraphQL helps when many clients need different slices of data. We often start with REST and add GraphQL where the need is clear.
Can you document our existing API?
Yes. We can reverse-engineer endpoints, produce an OpenAPI specification and add tests that lock in current behaviour. That gives you a safe base for refactoring or opening the API to others later.
How do you secure the API?
Through authentication, scoped permissions, input validation, rate limiting and encrypted transport, with secrets kept out of code. We also log access and review common risks such as broken object-level authorisation.
How are changes released without breaking apps?
We version the API, keep old versions working during an announced overlap and avoid removing fields abruptly. Usage per version is monitored so retirement happens only when real clients have moved.
More Custom Business Software services
All Custom Business Software servicesSystem Integration Services
Connect the systems you already run so that data is entered once, flows where it is needed and stays consistent everywhere.
Multi-Tenant SaaS Development
One platform serving many organisations, each with isolated data, its own branding and configuration, and no chance of seeing one another's records.
Payment Gateway Integration Services
Accept payments in your website or app through the gateways your customers use, with confirmations, refunds and reconciliation handled properly.
Ready to start your API Development Services project?
Tell us what you need and we will come back with a clear scope, timeline and the questions worth answering before any build starts.