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A self-hostable Grin payment server for shops, creators, and sites: show a code, Grin lands in your wallet, with a verifiable Grin payment proof on receive. Workspace crates (gp-core / gp-nostr / gp-server / gp-wallet / gp-goblin-sender), a WooCommerce connector, a hosted /pay/<token> checkout, and NIP-44 v3 gift-wrapped payment DMs carried over the Nym mixnet. All secrets are read from the environment; none are committed.
GoblinPay for WooCommerce
Accept Grin (GRIN / MimbleWimble) payments in WooCommerce through a self-hosted
GoblinPay server. The customer pays from their Goblin Wallet by scanning an
nprofile QR code. The payment travels as a gift-wrapped slatepack over Nostr
(optionally over the Nym mixnet). GoblinPay receives it, returns the reply
slatepack to the payer, watches the chain to confirm, and notifies WooCommerce.
This plugin is a thin client. All of the Grin and Nostr work happens in GoblinPay; WooCommerce only talks HTTP to your GoblinPay instance. No BTCPay, no node exposed to the store, no wallet RPC.
What it does
- Adds a "Grin (GRIN)" payment method to both the classic checkout and the WooCommerce Blocks (Cart/Checkout block) checkout.
- On checkout, calls GoblinPay to create an invoice for the order, then either
redirects the customer to GoblinPay's hosted
/pay/<token>page (the default) or shows the Goblin QR on the order-received page (the embedded option). - Marks the order complete when GoblinPay reports the payment, via a signed webhook. If a webhook is missed, the plugin polls GoblinPay for the invoice status as a fallback.
- Declares HPOS (custom order tables) and Cart/Checkout Blocks compatibility.
Requirements
- WordPress with WooCommerce 8.0 or newer (tested against WooCommerce 10.8).
- PHP 8.0 or newer (target host runs PHP 8.2).
- A running GoblinPay server reachable from the WordPress host.
Settings
Open WooCommerce, then Settings, then Payments, then GoblinPay (Grin).
- GoblinPay URL: base URL of your GoblinPay server, for example
http://127.0.0.1:8192. No trailing slash. - API Token: the GoblinPay create-invoice bearer token (
GP_API_TOKENon the server). - Webhook Secret: the shared HMAC secret (
GP_WEBHOOK_SECRETon the server). - Matching mode: how GoblinPay ties an incoming payment to the order. The default, per-invoice identity, gives each order its own QR and is the most reliable. Order reference (memo) and amount-only are also available.
- Checkout experience: redirect to the hosted GoblinPay checkout (the default), or embed the QR on the order-received page.
- Payment window: minutes before an unpaid order is cancelled. Set 0 to disable.
Point your GoblinPay server's GP_WEBHOOK_URL at this site's webhook endpoint,
shown in the Webhook Secret field, which is:
https://YOUR-SITE/wp-json/goblinpay/v1/webhook
Refunds
Refunds are not automated. GoblinPay is receive-only: it never sends Grin. A refund is therefore a manual, out-of-band Grin send by the merchant from a wallet under their control. This plugin marks refunds as unsupported for that reason, the same caveat the Grin BTCPay connector carries.
Security notes
- The webhook is authenticated by an HMAC-SHA256 signature over the exact raw
request body, compared in constant time (
hash_equals). A bad or missing signature is rejected with HTTP 401. - Webhook deliveries are deduplicated on their event id, and order completion is idempotent, so a retried or duplicated delivery is a no-op.
- The QR SVG rendered on the order-received page is passed through a strict
wp_ksesallowlist (svg, g, rect, path, image, title), so a compromised or misconfigured endpoint cannot inject script. - Secrets live in the gateway settings, never in code.
Credit
Built by Claude (Anthropic) for the Goblin project.