---
title: "SubKit"
description: "SubKit is the source of truth for product catalog, commerce, and access. Apps and backends read entitlements; store and payment providers are verified inputs."
---

# SubKit

SubKit owns versioned products and offerings, normalized subscriptions,
purchases, contracts and payments, distributable access capacity, invitation
reservations, allocations, and the resulting app-user or organization
entitlements. Apple, Google, and payment providers feed SubKit through verified
inputs — they never hold a competing license state.

## Pick your path

- **Build a mobile app** — Integrate purchases and access in Expo / React Native with the `@piparotech/subkit-expo` SDK.
Render offerings, run purchases, and gate features on entitlements. [Start
here](/docs/expo/overview/)
- **Build a backend** — Drive commerce and access from trusted server code with `@piparotech/subkit-node`: customers,
contracts, payments, seats, and entitlement checks. [Start here](/docs/node/overview/)
- **Operate the platform** — Connect stores, manage the catalog, and go live safely with verified reads and confirmed writes.
[Store setup](/docs/stores/overview/)

## The one rule that shapes everything

App code never asks "does this user have a subscription or license?" It asks
"does this **access subject** have this **entitlement**?" Every cause of access —
free enrollment, store subscription, purchase, contract, trial, promotion, or
manual provision — resolves through the same path:

```text
Access Source → Access Pool → Reservation/Allocation → Entitlement Grant
```

Read [Access model](/docs/concepts/access-model/) to understand why this keeps app
logic stable across single subscriptions, club seats, and every commerce cause.

## Architecture in one minute

![SubKit architecture: consumers use authenticated Runtime and Server interfaces; canonical catalog, commerce, and access domains derive grants from verified provider inputs and persistent state.](/subkit-architecture.svg)

Mobile apps use the Runtime API with public, app-bound keys. Trusted backends and
operators use the capability-scoped Server API. Both meet the same canonical
Catalog, Commerce, and Access domains. Store and payment systems remain outside
that boundary: adapters verify their evidence, then SubKit persists normalized
Sources and derives Pools, Allocations, and Grants. No consumer or provider
maintains a parallel license truth.

## Built for machines too

Every page is available as clean Markdown, and SubKit publishes curated
[`/llms.txt`](https://subkit.piparo.tech/docs/llms.txt) context files so coding
agents can load the smallest useful context instead of scraping HTML.

Source: https://subkit.piparo.tech/index.mdx