02035763719 info@app-one.co.uk Monday to Friday, 09:00 – 17:00

API Development & Integrations

Connect your software to the wider world. We design robust APIs and integrate the third-party services your business depends on.

Modern businesses run on connected software. AppOne designs and builds secure, well-documented APIs that let your systems share data cleanly — and we integrate the payment gateways, shipping providers, accounting tools and SaaS platforms you rely on.

We follow REST and GraphQL best practice, with versioning, authentication, rate-limiting and clear documentation, so your integrations are reliable today and easy to extend tomorrow.

What we deliver

Custom API Design

Clean, versioned REST and GraphQL APIs with authentication and rate-limiting.

Third-Party Integration

Stripe, PayPal, accounting, CRM, shipping and hundreds of SaaS platforms.

Webhooks & Events

Real-time, event-driven connections that keep your systems in sync.

Documentation

OpenAPI/Swagger docs so your developers and partners can integrate fast.

Why choose AppOne for API Development & Integrations

  • Secure authentication with OAuth 2.0 and API keys
  • Reliable retries, queuing and error handling
  • Middleware to bridge legacy and modern systems
  • Partner and public API programmes
  • Monitoring, logging and usage analytics

Frequently asked questions

Can you integrate a service that has no API?

Often yes — through secure data exchange, file-based integration or carefully built automation where a service lacks a formal API.

Do you document the APIs you build?

Always. Every API ships with interactive OpenAPI documentation so it is easy to use and maintain.

Ready to build something great?

Tell us about your project and get a free, no-obligation consultation with our UK team.