Guidance for connecting a backend to RevenueCat, which verifies app purchases and stores subscription status. It explains how a server can read or change that status without verifying Google Play receipts itself.

Use it to read subscriber status, grant or revoke access, manage subscriber attributes, and choose between API requests and webhooks for backend updates.

It prevents duplicated receipt-verification code and clarifies which RevenueCat API key and user identifier belong on the server.

rc-backend — Skill for Claude Code by RevenueCat

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add RevenueCat/ai-toolkit --skill rc-backend

Clone the repo

git clone --depth 1 https://github.com/RevenueCat/ai-toolkit

Made for: Claude Code.

Or install revenuecat-play-billing, the plugin that ships this one along with the rest of its 20 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/revenuecat/ai-toolkit/rc-backend/github.svg)](https://agentmods.dev/skills/revenuecat/ai-toolkit/rc-backend)

Your own site

<a href="https://agentmods.dev/skills/revenuecat/ai-toolkit/rc-backend"><img src="https://agentmods.dev/badge/skills/revenuecat/ai-toolkit/rc-backend/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/revenuecat/ai-toolkit/rc-backend"><img src="https://agentmods.dev/badge/skills/revenuecat/ai-toolkit/rc-backend.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 63 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,382 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

Socket pass 12 Jun 2026
Snyk warn 12 Jun 2026
NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 3 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

medium Data Exfiltration · line 73
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
medium Data Exfiltration · line 83
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
medium Data Exfiltration · line 95
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00063	$0.01382
Opus 5	$0.00032	$0.00691
Sonnet 5	$0.00013	$0.00276
Haiku 4.5	$0.00006	$0.00138

Measured 9d ago against content hash 668fcb56184d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

rc-backend scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

backend — 100% identical, 2 lines differ

revenuecat-play-billing/skills/rc-backend/SKILL.md · 137 lines

How it starts

The opening of the file, as written. The whole thing — 137 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Backend Architecture with RevenueCat

You do not build a receipt verification server with RevenueCat. Your backend still has a role, but that role is consuming RevenueCat state, not validating Google Play purchase tokens.

Phase 1: Discovery

RevenueCat's backend is the receipt verification server. When the Android SDK posts a purchase token, RevenueCat's backend:

Calls purchases.subscriptionsv2.get or purchases.products.get against the Google Play Developer API.
Validates the receipt is genuine and matches the expected product.
Records the transaction in its database.
Returns CustomerInfo to the SDK.

Your Android app never calls the Google Play Developer API. Your server does not call it either.

Before writing any backend code, confirm these facts about your deployment:

You have a RevenueCat project with an Android app configured.
You have a secret API key from Project Settings to API Keys (not the public Android SDK key embedded in the app).
You know which app_user_id your SDK uses (the same identifier your auth system uses).
You have decided whether the backend needs real time state (REST API) or event driven state (webhooks).

If your app only gates features inside the client, you may not need a backend component at all. RevenueCat verifies CustomerInfo server side before it reaches the SDK, and EntitlementVerificationMode.INFORMATIONAL or .ENFORCED adds signature verification on the client. Serve premium content from a server only when you can verify entitlement on the server.

Phase 2: Plan

Map each backend responsibility to a RevenueCat mechanism.

Use case	Mechanism	Notes
React to purchase, renewal, cancellation	Webhook receiver	RevenueCat posts normalized events; your server updates its own DB.
Check current entitlement for a user	`GET /v1/subscribers/{app_user_id}`	Secret API key in `Authorization` header.
Grant promotional access (support, refunds, comps)	`POST /v1/subscribers/{app_user_id}/entitlements/{entitlement_id}/promotional`	Server side only.
Revoke promotional access	`POST /v1/subscribers/{app_user_id}/entitlements/{entitlement_id}/revoke_promotionals`	Server side only.
Set subscriber attributes from server side data	`POST /v1/subscribers/{app_user_id}/attributes`	Useful for CRM fields the SDK does not know.
Bulk data export	RevenueCat data export	Scheduled exports to your warehouse.

Read the full file on GitHub · 137 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

9d ago First seen · 137 lines · 63 tokens per session scan A 668fcb56184d

Subscribe to this mod's changes

rc-backend is a skill published in the GitHub repository RevenueCat/ai-toolkit (65 stars, last pushed 7d ago), licensed MIT. It adds 63 tokens to every session and 1,382 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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