Quartermaster

The x402 toolkit for AI agents

Inspect and audit any x402 endpoint free — then verify settlements, decode payment challenges, and read Base chain data, paid per call in USDC. Plus AI, web, and developer utilities. No accounts, no API keys, no tracking.

Try it now — paste any x402 endpoint, get its decoded payment challenge. Free, no signup.
Powered by the free x402 Inspector. Agents/CI: the paid API has no rate limit.
Payments enabled — USDC on Base & Solana mainnet, settled per call via x402.

x402 V2 compatible - PAYMENT-REQUIRED / PAYMENT-RESPONSE headers, CAIP-2 networks, Bazaar discovery. See discovery.

51 tools, each with its own page, example, and FAQ. New here? Connect it to Claude or an agent, or read the buyer quickstart to pay your first call. Looking for one thing? Search below or browse all tools.

x402 tools

The builder's toolkit for the x402 payment ecosystem — inspect challenges, search the Bazaar, verify settlements. Nobody else's API does this.

$0.01
x402 Audit
Full scored audit of any x402 endpoint.
GET /v1/x402-audit
 $0.002
x402 Inspector API
The paid API for agents/CI. Humans: use the free browser tool.
GET /v1/x402/inspect
 $0.003
x402 Payment Simulator
Pre-flight a payment: cost per rail, and can your wallet afford it.
GET /v1/x402/simulate
 $0.03
Settlement Assurance
Prove a completed x402 payment is real and sound.
GET /v1/settlement-assurance

See all 10 x402 tools →

Crypto & Base

Read-only Base chain lookups for payments and settlement: transactions, balances, receipts, token data, Basenames. Nothing signed, no custody.

$0.002
Transaction Status
Base transaction status and confirmations.
GET /v1/tx
 $0.003
Transaction Decoder
Decode a Base transaction's calldata into a readable call.
GET /v1/tx-decode
 $0.001
Balance Check
ETH and USDC/ERC-20 balance on Base.
GET /v1/balance
 $0.003
Payment Proof
Verify an x402 settlement end to end.
GET /v1/payment-proof

See all 13 crypto & base →

AI

Summaries, translation, embeddings, extraction, moderation, and vision — on Workers AI, no external keys.

$0.01
AI Summarize
Fetch a page and return an AI summary.
GET /v1/summarize
 $0.005
AI Translate
Translate text into any language.
GET /v1/translate
 $0.005
Structured Extraction
JSON Schema in, matching JSON out.
GET /v1/extract-json
 $0.005
AI TL;DR
Summarize raw text you pass in.
GET /v1/tldr
 $0.002
AI Classify
Zero-shot classify text into your own labels.
GET /v1/classify

See all 9 ai →

Web & data

Fetch, read, and understand any public web page.

$0.005
Web Extract
Clean readable text from any web page.
GET /v1/extract
 $0.002
Page Metadata
Title, description, Open Graph, canonical, favicon.
GET /v1/meta
 $0.002
QR Generator
QR codes as SVG or terminal text.
GET /v1/qr
 $0.002
URL Unshortener
Expand a short link and show every redirect hop.
GET /v1/unshorten
 $0.001
HTTP Check
Is a URL up? Status, latency, and redirect in one call.
GET /v1/http-check

See all 7 web & data →

Developer utilities

Deterministic, zero-dependency helpers — handy extras agents reuse constantly.

$0.001
JWT Decoder
Decode a JWT header and payload.
GET /v1/jwt-decode
 $0.001
Text Diff
Line-level diff between two texts.
GET /v1/diff
 $0.001
Random Pick
Pick an option at random — the decision-maker.
GET /v1/pick
 $0.001
Public Holiday Check
Is a date a public holiday in a country?
GET /v1/holiday

See all 8 developer utilities →

Free tools

Open, no payment, no wallet — try the service instantly.

free
IP Info
Your IP, country, city, ASN, timezone.
GET /v1/ip
 free
UUID Generator
Generate UUID v4 values.
GET /v1/uuid

See all 4 free tools →

How payment works

Call a paid endpoint with no payment and you get 402 Payment Required plus machine-readable requirements. Attach payment with any x402 client and retry — two requests, settled in USDC on Base or Solana for a fraction of a cent. Full setup for Claude, Cursor, and agents is on Connect.