BSV 402 Payments

Automatic BRC-0121 payments for HTTP 402 resources via any available BSV wallet

BSV 402 Payments brings native micropayment support to your browser. When a website requires payment to access content — signaled by the standard HTTP 402 status code — this extension automatically handles the payment flow in the background, so you can access paid content as seamlessly as free content. Try it out by using this demo website: https://now.bsvblockchain.tech Prerequisite: You'll need a BRC-100 Wallet like https://desktop.bsvb.tech How it works The extension implements the BRC-0121 Simple 402 Payments protocol (https://brc.dev/121). When you navigate to a resource that returns HTTP 402 Payment Required, the extension: Reads the payment requirements from the server's response headers (amount in satoshis and the server's identity key) Connects to your BSV wallet to construct a payment transaction using the BRC-29 payment derivation protocol Retries your original request with the payment proof attached as HTTP headers The server validates the payment and serves the content All of this happens transparently — you just see the page load. Wallet connection This extension does not store keys or manage funds. It connects to an external BSV wallet that implements the BRC-100 Wallet Interface. Wallet discovery is automatic via the @bsv/sdk WalletClient, which checks for any available wallet substrate including: • BSV Desktop (desktop wallet application) • Any other BRC-100 compatible wallet running locally or accessible via supported transport A compatible wallet must be running for payments to succeed. All spending authorization and permission management is handled by the wallet — the extension never makes payments without wallet approval. Privacy • No data is collected, stored, or transmitted to any third party • No browsing history is tracked • No analytics or telemetry • The extension only activates when a server returns HTTP 402 with BRC-0121 headers • All communication is between your browser, the content server, and your local wallet Permissions explained • "Read and change all your data on all websites" (host_permissions: ) — Required to observe HTTP response headers on any website. The extension cannot predict which sites implement the 402 payment protocol. • "webRequest" — Used to detect HTTP 402 responses and read the x-bsv-sats and x-bsv-server response headers. • "declarativeNetRequest" — Used to attach payment proof headers (x-bsv-beef, x-bsv-sender, x-bsv-prefix, x-bsv-suffix, x-bsv-vout) to the retry request. • "tabs" — Used to reload the page after payment headers are installed. Technical details • Manifest V3 Chrome extension (service worker only, no content scripts, no UI) • Implements BRC-0121 (Simple 402 Payments) and BRC-100 (Wallet Interface) • Payment transactions use BRC-29 key derivation and BRC-95 BEEF transaction format • Source code: https://github.com/bsv-blockchain/402-extension • License: Open BSV License v4 Requirements • A BRC-100 compatible BSV wallet (such as BSV Desktop https://desktop.bsvb.tech) must be running • The wallet must be authenticated and have sufficient funds • Chrome 120 or later