index.md

id	domain-middleware
title	Middleware
kind	reference
last_updated	2026-07-27
version	n/a
last_verified	2026-07-27
review_cadence_days	90
status	stable
tags	packages middleware

Middleware Domain

Express.js middleware and client utilities for adding cryptographic authentication and micropayment gating to HTTP services. There are two distinct payment paths: @bsv/payment-express-middleware layers payment requirements on top of authenticated Express routes, while @bsv/402-pay is an independent HTTP 402 flow that can work without auth middleware.

Packages

Package	Purpose
@bsv/auth	Framework-neutral signed, expiry-bound, single-use wallet proofs with an injected replay store.
@bsv/auth-express-middleware	Express middleware implementing BRC-103 peer-to-peer mutual authentication via BRC-104 HTTP transport.
@bsv/payment-express-middleware	Authenticated legacy x-bsv-payment middleware with replay-safe payment acceptance.
@bsv/402-pay	Independent BRC-121 client and server HTTP 402 flow that does not require auth middleware.