App API & Backend Integration

REST is the right call when your mobile app has well-defined screens consuming predictable resources, when third parties or partners might also consume the API, or when HTTP caching matters. GraphQL is the right call when different screens need different data shapes from the same underlying entities, when you want to reduce over-fetching on mobile data connections, or when frontend teams need flexibility to evolve queries without backend changes. We help you pick during scoping — both are credible choices, the right one depends on your specific app.

OAuth 2.0 or JWT with proper refresh-token rotation — refresh tokens stored in iOS Secure Enclave or Android Keystore (not AsyncStorage where they'd be readable on a rooted device), short-lived access tokens, and biometric unlock for sensitive operations via Face ID, Touch ID, or BiometricPrompt where the platform supports it. Session handling accounts for mobile-specific patterns like background app refresh and app-state restoration. PCI-scope minimised by using Stripe's mobile SDKs or platform-native Apple Pay and Google Pay rather than handling card data directly.

Yes. We frequently build or extend backends for existing apps — typically the app was originally built against Firebase or a simple backend that has outgrown its scope, or the existing backend needs to evolve to support new features. We audit the existing integration surface, plan the new architecture, and migrate progressively rather than forcing a big-bang rewrite.

Payment platforms (Stripe, Stripe Connect, PayPal, GoCardless), push notifications (Firebase Cloud Messaging, OneSignal, Apple Push Notification service), analytics (Mixpanel, Amplitude, PostHog, Segment), CRMs (HubSpot, Salesforce), messaging (Twilio, SendGrid), social auth (Google, Apple, Facebook), and most bespoke partner APIs your business needs. Every integration is built with idempotency, signature verification, retry logic, and dead-letter handling — not the demo-path-only implementation that breaks in production.

Yes. Real-time delivered via WebSocket, Server-Sent Events, Pusher, Ably, or Supabase Realtime depending on the workload profile. Chat-like features with presence and typing indicators have different requirements from broadcast price updates, which have different requirements from collaborative document editing. We design the real-time architecture during scoping rather than picking a transport by default.

Yes — that's where most of our engineering effort goes. Duplicate webhooks handled idempotently. Token expiry handled with proper refresh flows. Third-party rate limits handled with exponential backoff. Network failures on mobile handled with queued retries and offline state. Partial outages of upstream services handled with graceful degradation. Reconciliation jobs catch the drift that does occur. The boring multi-year reality of running an app backend in production is what we build for.

Yes. Every API ships with an OpenAPI or GraphQL schema (depending on protocol), developer-facing documentation with worked examples, a Postman collection, 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.

Yes. We audit existing APIs against OWASP API top-10, authentication patterns, error handling, observability, and performance baselines — then propose either targeted upgrades or a strangler-fig refactor depending on the state of the code. Audit reports are written honestly with clear priority ordering, not designed to maximise scope.

Dependency and security patching, performance monitoring with regression detection, integration health monitoring (especially webhook delivery and reconciliation), cost optimisation on cloud infrastructure, and feature evolution. Available as a fixed monthly retainer alongside our API testing & monitoring, managed UK hosting, and database optimisation & maintenance services for full-stack operations.