Browser Proof

Browser Proof is evidence-backed web verification for agents.

Browser Proof is a verification component for agents that checks claims on public webpages and returns structured results with evidence text, screenshots, and deterministic JSON.

It is not a general-purpose browser automation product.
It is designed for situations where an agent needs external confirmation with evidence.

What it does

Browser Proof helps agents:

• verify whether a claim appears on a public webpage

• extract supporting evidence text

• capture a screenshot for auditability

• return a stable JSON response for downstream systems

Related MCP server: cross-validated-search

Production access

Production Browser Proof access now requires an API key.

• MCP remote access requires X-API-Key

• HTTP API access requires X-API-Key

• Registry visibility remains public for discovery, but live usage is not anonymous

Current launch plans:

• trial: 20 credits / month

• starter: 1000 credits / month

• pro: 10000 credits / month

Initial credit costs:

• verify_claim: 5 credits

• list_runs: 1 credit

• get_run: 1 credit

• get_run_screenshot: 1 credit

If you need a key for evaluation or paid use, contact RePrompt through the support or sales channel listed for this project.

Typical use cases

• Pricing check: confirm whether a price is actually shown on a page

• Policy validation: verify whether required language appears on a landing page

• Listing QA: confirm whether a job post, real-estate listing, or product page still matches expected facts

• Citation-backed research support: retrieve the exact text used as evidence

Quick start

HTTP API

curl -X POST https://proof.reprompt.jp/api/browser-proof \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://example.com",
    "task": "Check whether this page says it is for use in documentation."
  }'

Example response:

{
  "success": true,
  "answer": "Yes, the page states that it is for use in documentation examples.",
  "evidence_text": "This domain is for use in documentation examples without needing permission.",
  "source_url": "https://example.com",
  "checked_at": "2026-04-08T15:00:00Z",
  "screenshot_url": "supabase://browser-proof-evidence/example.com/root/2026-04-08T15-00-00-000Z.jpg",
  "error": null
}

Notes:

• screenshot_url is currently returned as an internal storage reference string.

• Clients that need a retrievable screenshot URL should use the run retrieval interfaces or MCP tools.

MCP connection

Browser Proof exposes remote MCP endpoints.

• Recommended (Streamable HTTP): https://proof.reprompt.jp/mcp

• SSE: https://proof.reprompt.jp/mcp/sse

See:

• server.json

• examples/

• docs/mcp.md

HTTP endpoints

• POST /api/browser-proof

• GET /api/runs

• GET /api/runs/:id

• GET /api/runs/:id/screenshot

• GET /health

Authentication

Production use requires an API key.

• Preferred header: X-API-Key: YOUR_API_KEY

• Bearer-style client configuration may be supported for compatibility, but X-API-Key is the canonical format

• Do not store live keys in this repository

• Keys are issued individually and may be rate-limited or credit-limited by plan

See:

• docs/auth.md

• examples/mcp/

Limits, retention, and privacy

See:

• docs/limits.md

• docs/retention.md

• docs/privacy.md

If a value is not finalized, mark it as planned or to be finalized. Do not present tentative values as final.

Repository purpose

This repository is the public shelf for Browser Proof:

• discovery

• connection details

• interface reference

• examples

• integration guidance

Implementation details live separately in the private core repository.

Related files

• agent-card.json

• server.json

• openapi.yaml

• schema/

• examples/

• docs/