x402-browser-bridge

npm install x402-browser-bridge

The problem

An enormous amount of commerce still lives behind a form. No API, no partner programme, no webhook — just a page, a submit button, and a confirmation screen. An agent that can pay for things cannot use any of it.

A bridge closes that gap: declare the click path once, expose it as an x402 endpoint, and the agent buys the outcome without ever knowing a browser was involved.

Pricing

Prices come from the flow files, so adding a YAML file adds a priced route — no code change.

A flow

name: demo-booking
price: "$0.05"
allowHosts: [localhost, 127.0.0.1]     # the security boundary. Required.

inputs:
  name:  { type: string, required: true }
  email: { type: string, required: true, pattern: '[^@\s]+@[^@\s]+\.[^@\s]+' }
  date:  { type: string, required: true, pattern: '\d{4}-\d{2}-\d{2}' }

steps:
  - goto: "{{baseUrl}}/demo/booking.html"
  - type:   { selector: "#name",  value: "{{inputs.name}}" }
  - type:   { selector: "#email", value: "{{inputs.email}}" }
  - select: { selector: "#party", value: "{{inputs.partySize}}" }
  - screenshot: form
  - click: "#submit"
  - waitFor: "#confirmation:not([hidden])"
    timeoutMs: 8000
  - screenshot: confirmation

extract:
  reference: { selector: "#reference" }
  errorMessage: { selector: "#error:not([hidden])", optional: true }

Steps: goto · click · type · select · press · waitFor · waitForText · wait · scroll · screenshot. A flow cannot execute arbitrary JavaScript — templating is {{inputs.x}} and {{baseUrl}}, nothing more. Adding a flow is a config change with a reviewable diff.

Failure is an artifact, not an error

A failed run is still a 200: the payment settled before the browser started, so a bare 500 would take the money and teach the caller nothing. Instead you get the step that broke, a screenshot of the page at that moment, and whatever the site said — which is usually the actual answer ("no tables available"), not a bug.

What fails free, before payment: unknown flow (404), malformed inputs (400), and no browser available (503).

Safety model

Both rails, always

Docs