Integrating Claude AI into Android apps — a practical guide

Three of my live apps — BotsApp, CalorieIQ, and Ask Anything — are built around Anthropic's Claude API. After shipping all three, I've settled on an integration pattern that is simple, resilient, and cheap to run. This post walks through it end to end.

Never ship your API key in the APK

The single most important rule: the Claude API key never touches the Android app. Anything bundled in an APK can be extracted in minutes. Instead, the app talks to a tiny backend proxy — mine is a single serverless function — which holds the key, enforces per-user rate limits, and forwards requests to the Anthropic API.

This also gives you a kill switch. If a version of the app misbehaves or someone abuses the endpoint, you rotate one server-side key and every client is covered.

Streaming responses with Kotlin coroutines

Waiting three seconds staring at a spinner feels broken; watching an answer type itself out feels alive. The Claude API supports server-sent events, and on Android I consume them with OkHttp and a Kotlin Flow. Each SSE chunk is emitted into the Flow, and Jetpack Compose collects it straight into the message bubble.

The whole streaming layer is about 80 lines of Kotlin. The key detail is cancellation: when the user leaves the screen, the coroutine scope cancels, the OkHttp call is torn down, and you stop paying for tokens nobody will read.

Handling rate limits gracefully

You will hit 429s. Plan for them on day one. My proxy returns a structured error with a retry-after hint, and the app degrades politely: the send button shows a brief cooldown instead of a scary error dialog. Users mostly never notice.

Treat the AI layer like any other unreliable network dependency — because that is exactly what it is.

Costs in practice

With Claude Haiku for short interactions and careful prompt design, my per-user cost stays comfortably in fractions of a cent per session. Cache your system prompts, keep context windows tight, and the economics of AI features in indie apps work out fine.

If you're building something similar and want to compare notes, reach out — I'm always happy to talk shop about AI on Android.