@xpayr/extension-kit

Crypto-native licensing for browser extensions. The license is the paying wallet — no email, no license keys, no accounts, no chargebacks.

const xpayr = XPayrKit('prod_my_extension');

const user = await xpayr.getUser();
if (user.licensed) {
  unlockProFeatures();
} else {
  xpayr.openCheckout();
}

Why this exists

Chrome Web Store payments shut down in February 2021. Every extension developer now needs an external payment layer, and the leading option requires a Stripe account — which excludes developers in Turkey, Pakistan, Nigeria, Bangladesh, Indonesia, Egypt and many other countries entirely.

Crypto payment gateways stop at "payment received". They give you a webhook, not a license: no entitlement store, no SDK, no cross-device verification. You end up building the hard half yourself.

This kit is the missing half.

| | ExtensionPay | Paddle / Lemon Squeezy | Crypto gateways | XPayr Kit | |---|---|---|---|---| | Fee | 5% + Stripe's 2.9%+30¢ | 5% + 50¢ | 0.5–1% | 2.9% flat | | Works without Stripe | ❌ | ⚠️ | ✅ | ✅ | | Entitlement/licensing layer | ✅ | ⚠️ partial | ❌ | ✅ | | Chargebacks | yes | yes | none | none | | Merchant of record (tax) | ❌ | ✅ | ❌ | ❌ |

First $300 of sales are free.

Install

npm install @xpayr/extension-kit

Or copy src/index.js into your extension — it has zero dependencies and no build step.

Manifest (MV3)

{
  "permissions": ["storage", "alarms"],
  "externally_connectable": { "matches": ["https://xpayr.com/*"] }
}

No host_permissions, so installing your extension shows no scary permission warning. externally_connectable makes unlock instant; without it the SDK falls back to a short polling window, so it still works.

Background script

import XPayrKit from '@xpayr/extension-kit';

const xpayr = XPayrKit('prod_my_extension');
xpayr.startBackground();   // required — wires token delivery + daily refresh

xpayr.onLicenseChanged.addListener(user => {
  console.log(user.licensed ? 'unlocked' : 'locked');
});

API

| Method | Description | |---|---| | getUser() | Offline-first license check. Verifies the cached ES256 token locally, so it returns in ~0 ms and works with no network. | | openCheckout() | Opens the hosted checkout in a new tab. Buyer picks any supported network/token. | | openRestore() | "I already bought this" — unlocks another device by signing with the paying wallet. | | refresh() | Forces online revalidation (picks up refunds/revocations). | | getPlans() | Public product info: price, plan type, allowed networks. | | onLicenseChanged | Fires whenever the license state changes. |

user object

{
  licensed: boolean,      // gate your features on this
  plan: 'lifetime' | 'prepaid_year' | 'trial' | null,
  wallet: string | null,  // the wallet the license is bound to
  paidAt: Date | null,
  expiresAt: Date | null, // null for lifetime
  source: 'cache' | 'network',
  staleSince: Date | null // set while running on offline grace
}

How verification works

1. The buyer pays from their wallet on the hosted checkout.
2. XPayr records the entitlement against the wallet address that paid.
3. The buyer signs a free, single-use message (no funds move) proving they control that wallet.
4. XPayr returns an ES256-signed JWT, scoped to your product (aud) and valid 7 days.
5. The SDK verifies that token locally with WebCrypto on every getUser() and silently renews it once a day.

Offline for a while? The SDK keeps the license working for 30 days past the token's expiry, then soft-locks with a prompt to reconnect — no one gets locked out mid-flight.

Refunded a customer? Revoke in the dashboard: refresh fails immediately and the token dies within 7 days.

Migrating from ExtensionPay

| ExtPay | XPayr Kit | |---|---| | ExtPay('extension-id') | XPayrKit('prod_code') | | extpay.startBackground() | xpayr.startBackground() | | user.paid | user.licensed | | user.email | user.wallet | | openPaymentPage() | openCheckout() | | openLoginPage() (email magic link) | openRestore() (wallet signature — instant) | | onPaid.addListener (needs a content script) | onLicenseChanged.addListener (no content script) | | getPlans() | getPlans() |

Honest limitations

• Client-side licensing is a deterrent, not DRM. Anyone determined can patch a local check — true of every library in this category. What this model adds is that "sharing a license" means sharing a wallet signature, and nobody lends out their wallet.
• Not a merchant of record. You are responsible for your own tax reporting. Paddle/Lemon Squeezy handle that; that is what their higher fee buys.
• The buyer needs a wallet. For crypto-native audiences that is a non-issue; for general consumers, run a fiat rail alongside this one.
• No pull-based subscriptions. Crypto has no card-on-file. v1 supports lifetime and prepaid annual licenses.

Links

• Product & docs: https://xpayr.com
• Pricing: 2.9% flat, first $300 free
• Non-custodial by design: XPayr never holds your funds or keys

License

MIT — see LICENSE. The XPayr name and logo are trademarks; see TRADEMARKS.md.