API Development - REST & GraphQL

REST is the right default for most products: it is cache-friendly, well-understood, and straightforward for third-party consumers. GraphQL shines when multiple clients (web, mobile, partner) need to fetch different shapes of the same data without separate endpoints. We help you choose based on your query patterns and team capabilities, and we can run both side by side when needed.

We use URL-based versioning (/api/v1, /api/v2) for public APIs because it is explicit and easy to route. For internal services we often use header-based versioning or a gateway pattern. We always define a deprecation policy upfront - typically a 6-month overlap - so existing integrations are never broken unexpectedly.

Every API we build goes through OWASP Top 10 review. We enforce HTTPS everywhere, implement strict CORS policies, use parameterised queries to prevent SQL injection, and apply rate limiting to mitigate brute-force and DDoS. Secrets are managed through environment variables or a secrets manager - never hardcoded.

Yes. We regularly build integrations with payment gateways (Stripe, PayPal), communication tools (Twilio, SendGrid), CRMs (HubSpot, Salesforce), and cloud storage (S3, GCS). We wrap third-party calls in retry logic, circuit breakers, and fallback handlers so a partner outage does not cascade into your product.

We profile every endpoint against realistic load before launch using tools like k6. Performance patterns we apply include database query optimisation with EXPLAIN ANALYSE, Redis caching for expensive reads, connection pooling, and pagination enforced by design. We set latency budgets (e.g. p99 < 200ms) and alert when they are breached.

Yes. We auto-generate OpenAPI 3.0 specs from our route definitions so documentation is always in sync with the implementation. We also write a developer guide covering authentication flows, common use cases, and error handling. For public APIs we can host an interactive Swagger UI or Redoc page.

We write unit tests for business logic, integration tests that run against a real database, and contract tests that catch breaking schema changes before they reach production. All tests run in CI on every pull request. We aim for meaningful coverage of business-critical paths rather than chasing an arbitrary percentage.

Absolutely. We perform API audits covering security, performance, design consistency, and documentation quality. The output is a prioritised report with specific recommendations. We then work through improvements incrementally so existing consumers are not disrupted.

For webhooks we implement signed payloads (HMAC-SHA256), retry queues with exponential backoff, and idempotency keys so duplicate deliveries are safe. For heavier event-driven architectures we use message queues - SQS, RabbitMQ, or Kafka - depending on throughput and ordering requirements.

It depends on the number of resource types and how much business logic sits behind them. For sizing, the model behind our calculator counts a web backend as 280-460 hours of base work - schema, endpoints, auth wiring, CI and releases - and every integration with a system you already run as a further 70-180 hours. A well-scoped API of that shape runs 8-15 weeks. Larger platforms with many resource types take longer, and we scope them after reviewing your data model. Price it at kultrix.com/cost-calculator.

We recommend starting with a well-structured monolith unless you have a clear organisational or scaling reason to split early. Premature microservices add operational overhead that slows most teams down. When you do need to split, we plan service boundaries around business domains and introduce an API gateway to manage routing and cross-cutting concerns.

Yes. All code written for your project is yours from the moment it is delivered. We transfer full IP rights, provide access to all repositories, and ensure there are no proprietary dependencies that could lock you in. You can hire another team to continue the work at any point.