Freemius JavaScript

Type-safe Freemius integration toolkit: a production-focused TypeScript/JavaScript SDK plus a React / Next.js Starter Kit for implementing subscriptions, one‑off purchases, license & entitlement validation, and a secure self-service customer portal.

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Looking for a step‑by‑step walkthrough of backend checkout generation, secure purchase validation, local entitlement storage, webhook‑driven license lifecycle syncing, and feature gating logic? Check out the guides below.

• Next.js / React Starter Kit Integration.
• Framework Agnostic Integration.

We also have the React Starter Kit you can use on your front-end to quickly render Checkout overlays, pricing tables, and a customer portal.

Support / Questions

• Core SDK Docs: https://freemius.com/help/documentation/saas-sdk/js-sdk/
• Next.js Integration: https://freemius.com/help/documentation/saas-sdk/framework/nextjs/
• General Integration Flow: https://freemius.com/help/documentation/saas-sdk/js-sdk/integration/
• React Starter Kit: https://freemius.com/help/documentation/saas-sdk/react-starter/
• Issues / Bug Reports: https://github.com/Freemius/freemius-js/issues

Please open an issue for reproducible defects or clearly scoped feature gaps that align with the minimal, execution‑oriented philosophy of this repository.

Features & Packages

@freemius/sdk (Server / Edge Runtimes)

Focused, framework‑agnostic primitives for securely interacting with the Freemius platform:

• Typed API Client: Fine-tuned OpenAPI-derived API classes to easily interact with the Freemius REST API.
• Checkout Utilities: Create Checkout URLs or Options for the Overlay mode, sandbox mode, redirect result parsing etc.
• Webhook Processing: HMAC‑SHA256 signature verification + event listener abstraction
• Purchases & Entitlements: License retrieval, entitlement state validation, minimal model helpers

See the full documentation for all exported capabilities.

React Starter Kit (Next.js / React)

An opinionated, production‑ready reference implementation showing how to operationalize the SDK inside a modern React / Next.js stack. Built with shadcn/ui + Tailwind CSS.

Included building blocks:

• Checkout: CheckoutProvider + context wiring for invoking overlay checkout from any component
• Pricing / Paywall: Subscribe & Topup components for plan display, subscription initiation, and credit top‑ups
• Customer Portal: Authenticated portal UI for subscription, billing method, and invoice management

See the Starter Kit docs for component APIs and integration notes.

Security Notes

Hard requirements for a correct integration:

• Secrets: Never expose API_KEY, SECRET_KEY, or signing material to the browser or untrusted execution contexts.
• Webhooks: Always verify the HMAC‑SHA256 signature using the raw, unparsed request body before mutating state.

Contributing

1. Fork & clone
2. npm install
3. Create a feature branch (e.g. feat/<concise-scope>)
4. Implement change; run local builds / lint; add or update a changeset (npx changeset) if publishing a package change
5. Commit with a precise, imperative message
6. Open a PR referencing any related issue(s)

Read Contribution Principles for more details.

License

MIT © Freemius Inc

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Payments, tax handling, subscription lifecycle management, and licensing are abstracted so you can focus on product functionality rather than billing infrastructure.

https://freemius.com