API Development Services

What we build

REST, GraphQL or gRPC?

Most products need REST, with GraphQL added where front ends benefit from it.

How we design APIs that last

• Design first — OpenAPI or GraphQL schema agreed before coding, so front-end and back-end teams work in parallel.
• Consistent conventions — naming, pagination, filtering and error formats that developers can predict.
• Versioning — a clear policy so changes never break existing clients without notice.
• Security — OAuth 2.0 / OpenID Connect, API keys, rate limiting and input validation.
• Observability — request logging, tracing and usage dashboards.

Documentation and developer experience

• Interactive documentation generated from the specification
• Example requests and responses for every endpoint
• A sandbox environment and test keys for partners
• SDKs or Postman collections where useful
• A changelog and deprecation notices

Designing an API your partners will love

Developers judge an API in the first hour: whether they can get a key, make a successful call and understand the response without asking for help. Good API design is therefore as much about empathy as engineering. We use predictable resource names, plural nouns, consistent date formats and clear error messages that explain what went wrong and how to fix it.

Pagination, filtering and sorting follow the same pattern on every endpoint, so learning one teaches all. Long-running operations return immediately with a job ID rather than timing out. Webhooks are signed so receivers can verify them, retried with backoff when a receiver is down, and visible in a dashboard. Rate limits are documented and communicated through response headers before clients hit them. These details are what separate an API partners recommend from one they tolerate.

Integrating with third-party APIs safely

Most products also consume other companies’ APIs — payments, shipping, CRMs, accounting, AI models. Each external dependency is a risk: it can slow down, change or fail. We isolate integrations behind internal adapters so a provider can be swapped without touching the rest of the code, apply timeouts and circuit breakers so one slow service cannot take down your product, queue non-urgent calls, and log every request and response (with sensitive data masked) for troubleshooting.

Versioning and change management

An API is a contract. Once other teams or partners depend on it, every change carries risk. A clear versioning policy lets you improve the API without breaking the systems built on it.

Whatever the approach, we publish a deprecation policy, announce changes in a changelog, return deprecation headers and monitor which clients still call old versions before switching anything off.

Security checklist for production APIs

• Authentication with OAuth 2.0 / OpenID Connect or scoped API keys — never shared credentials
• Authorisation checked on every request at the object level, not only per endpoint
• Input validation against a schema, with clear error responses
• Rate limiting and quotas per client to prevent abuse and noisy neighbours
• TLS everywhere, secrets in a vault and keys that can be rotated
• Audit logging of sensitive operations without logging personal data unnecessarily
• Automated tests for the OWASP API Security Top 10 risks in the CI pipeline

Performance and reliability

Slow APIs usually come from a few predictable causes: too many database queries per request, missing indexes, large unpaginated responses and synchronous calls to slow third parties. We design for speed from the start with pagination, field selection, caching of read-heavy endpoints and background jobs for long-running work, returning a job ID that clients can poll or receive through a webhook.

Reliability features matter as much as speed: idempotency keys so retried payments or orders are not duplicated, timeouts and circuit breakers around external dependencies, and health checks that monitoring can watch.

A typical API project

1. Discovery1–2 weeks

   Identify consumers, use cases, data ownership and security requirements.

2. Contract first1–2 weeks

   Write the OpenAPI or GraphQL schema and review it with consumers before coding.

3. Build & test3–8 weeks

   Implement endpoints with automated contract, integration and security tests.

4. Developer portal1–2 weeks

   Publish reference docs, guides, sandbox keys and code samples.

5. OperateOngoing

   Monitor latency, errors and usage; evolve the API without breaking clients.

Timings are typical for a focused API; platforms with many consumers take longer.

Questions to ask an API development partner

• How do you design the contract before writing code, and who reviews it?
• How will you test that changes do not break existing consumers?
• What is your approach to authentication, rate limiting and audit logging?
• Which monitoring and alerting will be in place at launch?
• Who owns the documentation, and how is it kept in sync with the code?

See also API testing, enterprise integration and microservices development.

Webhooks and event-driven integrations

Polling an API every few minutes wastes resources and delays updates. Webhooks let your API notify consumers the moment something happens — an order is paid, a ticket is updated, a document is signed. Reliable webhooks need signed payloads so receivers can verify the sender, automatic retries with back-off when a receiver is down, a delivery log consumers can inspect and the ability to replay missed events.

For internal systems with high volumes, we often use a message broker or event bus instead, so services can react to events independently without calling each other directly. This keeps systems loosely coupled and easier to change.

Whichever model fits, we document the event types, payload schemas and delivery guarantees alongside the rest of the API, so integrators know exactly what to expect.

Measuring API health

We track a small set of signals for every production API: request volume per consumer, error rates split by client and server errors, latency at the 95th and 99th percentile, and the age of the oldest version still in use. Alerts fire on sustained changes rather than single spikes, so the team responds to real problems without alarm fatigue. Usage data also shows which endpoints matter most and which can be deprecated safely.

To add API specialists to your team, you can hire backend developers.

Timeline and cost drivers

A focused integration between two systems often takes three to six weeks. A full product or public API takes longer, depending on the number of resources, authentication model, rate-limiting and documentation needs.

APIs often sit behind web applications and CRM integrations.

This page is part of Web Development Services — see the full overview for related services, approach and pricing.