The subscription stack for Expo apps.

Our opinionated stack for a subscription Expo app: Expo and EAS own builds, updates, and submission; RevenueCat owns store purchases and receipt validation; Amba owns everything after the purchase — auth, entitlement state, segments, push campaigns, streaks, and analytics. An AI agent provisions the Amba layer over MCP in about ten seconds; the full wiring is a 30-minute job.

This is a recipe, not a survey — and we are one of its three layers, so read it as a first-party opinion with the receipts shown. The division of labor is the whole idea: each layer does the thing it is genuinely best at, and the seams between them are explicit. Expo never touches your backend; RevenueCat never runs your engagement loop; Amba never validates a receipt. Features in your app check one thing — an Amba entitlement — so every layer composes through one explicit seam instead of fusing into a ball of vendor glue. Every command, tool call, and SDK line below is verified; the timed budget covers software wiring, not App Store paperwork.

The connective tissue is one webhook: RevenueCat reports subscription events to Amba, and Amba turns them into entitlements, segment membership, and push targeting. Details on exactly what syncs: /integrations/revenuecat.

1. 01

   Provision the Amba layer

   ~1 min

   Point your coding agent at the hosted MCP server and have it sign up. amba_developer_signup mints a developer token and a provisioned project — client key and server key included — with no browser; the project goes active in about ten seconds.

   Agent connects + provisions

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   $ claude mcp add --transport http amba https://mcp.amba.dev/mcp
   
   amba_developer_signup { "email": "you@app.com", "password": "<min 8 chars>" }
   → returns pat + project with client_key and server_key

2. 02

   Install both SDKs

   ~3 min

   Two installs. The Amba Expo SDK is pure JS over HTTPS and runs in Expo Go; react-native-purchases is a native module, so purchases need a development build — that constraint is RevenueCat-on-Expo, not this stack.

   Install

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   npx expo install @layers/amba-expo @react-native-async-storage/async-storage
   npx expo install react-native-purchases

3. 03

   Configure both SDKs with one shared user identity

   ~5 min

   Configure Amba with the project keys the agent handed back, configure RevenueCat with its public SDK key, and use ONE stable user key on both sides: RevenueCat's app_user_id must equal the Amba user's external_id so webhook events resolve to the same person.

   App startup

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   import { Amba } from '@layers/amba-expo';
   import Purchases from 'react-native-purchases';
   
   await Amba.configure({ projectId: 'proj_…', clientKey: 'amba_ck_…' });
   await Amba.auth.signInAnonymously();
   
   // One identity across layers: RevenueCat's app_user_id must match the
   // Amba user's external_id so subscription events land on the same person.
   Purchases.configure({ apiKey: '<RevenueCat public SDK key>' });
   await Purchases.logIn('<your stable user key — set as external_id in Amba>');

4. 04

   Declare the entitlement contract in Amba

   ~5 min

   The agent defines the entitlement your app gates on and maps the store products that grant it. Features check the entitlement, never a product or a store — one seam, checked in one place, no matter how your catalog grows.

   Entitlement + product map

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   amba_entitlements_define
     { "project_id": "proj_…", "key": "pro", "display_name": "Pro" }
   
   amba_products_create
     { "project_id": "proj_…", "product_id": "pro_yearly",
       "grants_entitlement_id": "pro",
       "store_product_refs": { "app_store": "com.yourapp.pro.yearly",
                               "play_store": "pro-yearly" } }

5. 05

   Connect RevenueCat to Amba

   ~5 min

   amba_integrations_configure stores your RevenueCat secret API key plus a webhook secret and returns the exact webhook_url. Register that URL in RevenueCat's webhook settings with the same Authorization header value, then verify with amba_integrations_test. From now on every purchase, renewal, and expiration syncs server-side.

   The one webhook

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   amba_integrations_configure
     { "project_id": "proj_…", "provider": "revenuecat",
       "config": { "secret_api_key": "<RC secret API key>",
                   "webhook_secret": "<long random string>" } }
     → webhook_url: https://api.amba.dev/webhooks/revenuecat?project_id=proj_…
   
   amba_integrations_test { "project_id": "proj_…", "provider": "revenuecat" }

6. 06

   Sell with RevenueCat, gate with Amba

   ~5 min

   The paywall and purchase flow run on RevenueCat's SDK. Your feature gates read Amba — server-synced entitlement state, no receipt parsing in the app, survives reinstalls and device switches.

   Feature gate

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   // Purchase happens through RevenueCat's SDK on device.
   // Gating reads Amba — synced server-side by the webhook.
   const isPro = await Amba.entitlements.has('pro');
   
   // After a reinstall or device switch, force a re-sync.
   await Amba.entitlements.restore();

7. 07

   Wire the engagement loop

   ~6 min

   This is the part the other two layers do not do: a live "active subscribers" segment from the synced subscription properties, a push campaign targeting it, a streak to bring users back daily, and optionally a reward rule on entitlement.granted.

   Subscription state drives engagement

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   amba_segments_create
     { "project_id": "proj_…", "name": "Active subscribers",
       "rules": { "operator": "AND", "conditions": [
         { "field": "properties.subscription_active", "op": "eq", "value": true }
       ] } }
   
   amba_push_campaigns_create
     { "project_id": "proj_…", "name": "Pro welcome",
       "title": "You're in", "body": "Pro is live on this device.",
       "segment_id": "<segment id>" }
   
   amba_streaks_create
     { "project_id": "proj_…", "name": "Daily practice",
       "qualifying_event": "session_completed" }

A server or a webhook handler

RevenueCat events land on a hosted Amba endpoint with dedup, ordering guards, and retries built in. There is no handler to write, no queue to run, nothing to deploy or babysit.

A receipt-validation service

RevenueCat owns store receipt validation end to end. Your app never parses a receipt, and your backend never talks to App Store or Play billing APIs.

A cron for subscriber lists

Segments re-evaluate when subscription state changes and on a schedule. "Lapsed subscribers" is a live cohort, not a nightly export.

A separate push provider

Campaigns, segment targeting, and scheduling are built into Amba, delivering over APNs and FCM. One fewer SDK, one fewer dashboard, one fewer bill.

A second pipeline for engagement analytics

Amba.events.track feeds funnels, retention, and segment rules in the same backend. RevenueCat keeps the revenue analytics — that split is intentional, not a gap.