x402 payment protocol · Base, Polygon, Arbitrum + Solana

APIs your agent can pay for by the request.

No API keys, no signups, no subscriptions. Every route here is metered in USDC — call it, get an HTTP 402 with the price, sign a payment, and the data comes back. Built on the open x402 protocol.

21
Monetized routes
$0.001–$0.05
Per-call price range
4 chains
Payment networks
0
API keys required
Featured agent

Gold Source Indexing Agent

Send a document as text, a public URL, or a file upload (plain text, HTML or PDF). You get back a section tree that points to the exact source text instead of rewriting it: every section and block has a [start, end) span, its section path and a SHA-256 fingerprint, plus a coverage check that shows whether any text was left out.

  • Text, HTML or PDF
  • URL or file upload
  • Exact [start, end) spans
  • SHA-256 per node
  • Coverage check
  • Stateless
Request — paste into a terminal; the first reply is an HTTP 402 with the price
curl -X POST https://agentx402pay.com/api/gold-index \
  -H "Content-Type: application/json" \
  -d '{"text":"SERVICES AGREEMENT\n\nARTICLE 1 - SERVICES\nProvider will deliver the Services described in Exhibit A.\n\nARTICLE 2 - FEES\nClient pays $2,500 per month, due within 30 days of invoice.\nLate amounts accrue interest as set out in Section 2.3.","filename":"services-agreement.txt"}'
200 OK after payment — abridged from the spec example
{
  "goldMeta": {
    "hash": "2ab4a039efcc241763219a21f101fb51ffaec73696f0e3fd99f1c3ed01122f01",
    "offsetUnit": "utf16-code-unit",
    "nodeCount": 5,
    "coverage": {
      "indexedNonWhitespaceChars": 193,
      "totalNonWhitespaceChars": 193,
      "complete": true
    }
  },
  "tree": {
    "children": [
      {
        "type": "SECTION",
        "title": "ARTICLE 1 - SERVICES",
        "sectionPath": [
          "ARTICLE 1 - SERVICES"
        ],
        "goldPointer": {
          "start": 20,
          "end": 40,
          "fullTextHash": "6a75606bef13f06ed6132c6c61a547351eb8d83cad12eaa20a2cce95608f1616"
        }
      },
      "…"
    ]
  }
}
agent session · AgentX402Pay
402x402 · usdc
$
Payment networks

Pay from whatever chain you already hold USDC on

19 of the 21 routes on this page take payment on all four networks and work the same way on each: sign, retry, get the response. As of August 2026 that includes Ethereum's two largest L2s alongside Base, plus Solana for the non-EVM path. The other 2, /api/generate and /api/ping, take Base only. One address per chain family, same USDC price everywhere.

B
BaseEthereum L2
eip155:8453

Coinbase's L2 — the original network every route here shipped on.

Accepting USDC now
P
PolygonEthereum L2
eip155:137

High-volume, low-fee settlement — added August 2026.

Accepting USDC now
A
ArbitrumEthereum L2
eip155:42161

Optimistic-rollup throughput — added August 2026.

Accepting USDC now
S
SolanaL1
Solana mainnet

Sub-second finality — the non-EVM option, wired since launch.

Accepting USDC now
Protocol pulse

x402 doesn't just run on this server

This is real, live activity across the whole x402 ecosystem — every seller, every facilitator — not just traffic to AgentX402Pay. The same open protocol every route on this page speaks.

Live · x402 protocol, every seller

Real ecosystem-wide activity — not just this server. Data via agentic.market.

Connecting to the live feed…
How it works

Three requests, no dashboard

x402 turns HTTP 402 Payment Required from a dead status code into a working payment flow. There's nothing to configure before your first call. Scroll to watch each step highlight the matching part of the exchange.

1

Call the endpoint

No payment attached, so the server replies 402 with the exact price and payment instructions.

2

Sign a payment

Your wallet (or agent's x402 client) signs a USDC payment for that exact amount — no on-chain transaction yet.

3

Retry and get paid data

Resend the request with the signed payment attached. The payment is verified, the route runs, and the response comes back.

Payment flow

Follows the step you're reading.

GET /api/weather?city=Austin → 402GET
sign $0.01 USDC → BaseSIGN
200 OK · settled on Base200
Endpoints

Everything this server sells

Every route below prices in USDC, settles only after a successful response (a request that fails is not charged), and declares Bazaar-compatible discovery metadata. All take GET requests except /api/gold-index, which takes the document in a POST body.

Flagship examples

6

Each demonstrates a different x402 payment pattern — fixed price, usage-based, dynamic pricing, and payment channels.

HTML page
/protectedfixed

A whole paid page, not a JSON API — same per-route x402 gating as every other endpoint.

No query params required.

https://agentx402pay.com/protected

simulated — no real payment sent
Fixed price
/api/weather$0.01

Live current weather for any city, sourced from Open-Meteo.

  • city= Austin

https://agentx402pay.com/api/weather?city=Austin

simulated — no real payment sent
Usage-based
/api/generateup to $0.05

Buyer authorizes a max in one signature; you charge only for the output actually generated. Base only.

  • prompt= explain x402 in one paragraph

https://agentx402pay.com/api/generate?prompt=explain%20x402%20in%20one%20paragraph

simulated — no real payment sent
Dynamic price
/api/insights$0.01 / $0.025

Topic attention from Wikipedia page views: 7-day average, week-over-week change and peak day. Premium adds the daily series, spikes and related topics.

  • tier= premium
  • topic= ai agents

https://agentx402pay.com/api/insights?tier=premium&topic=ai%20agents

simulated — no real payment sent
Batch settlement
/api/ping$0.001

Cheap repeatable calls accumulate in one payment channel, settled on a schedule instead of per-call. Base only.

No query params required.

https://agentx402pay.com/api/ping

simulated — no real payment sent
POST
/api/gold-index$0.05

Indexes a document without rewriting it: exact [start, end) text spans, section paths and SHA-256 fingerprints, plus a coverage check.

POST JSON {"text": "..."} or {"url": "..."}, a text/plain body, or a multipart "file" (text, HTML or PDF)

No query params required.

https://agentx402pay.com/api/gold-index

simulated — no real payment sent

Data endpoints

11

Prediction markets, DeFi, crypto market data, and web search — the categories driving the most real usage across the x402 ecosystem today.

/api/polymarket-markets$0.01

Search/list Polymarket prediction markets by volume

  • q= election
  • limit= 10

https://agentx402pay.com/api/polymarket-markets?q=election&limit=10

simulated — no real payment sent
/api/polymarket-market$0.01

Single Polymarket market detail by slug

  • slug= will-btc-hit-100k(required)

https://agentx402pay.com/api/polymarket-market?slug=will-btc-hit-100k

simulated — no real payment sent
/api/kalshi-markets$0.01

Search/list open Kalshi prediction markets

  • q= fed
  • limit= 10

https://agentx402pay.com/api/kalshi-markets?q=fed&limit=10

simulated — no real payment sent
/api/kalshi-market$0.01

Single Kalshi market detail by ticker

  • ticker= FED-24DEC(required)

https://agentx402pay.com/api/kalshi-market?ticker=FED-24DEC

simulated — no real payment sent
/api/defi-tvl$0.01

DeFi protocol TVL, by chain + market cap

  • protocol= aave(required)

https://agentx402pay.com/api/defi-tvl?protocol=aave

simulated — no real payment sent
/api/defi-chains$0.01

Rank blockchains by total DeFi TVL

  • limit= 15

https://agentx402pay.com/api/defi-chains?limit=15

simulated — no real payment sent
/api/crypto-price$0.01

Price + 24h change for one or more coins

  • ids= bitcoin,ethereum(required)
  • vs= usd

https://agentx402pay.com/api/crypto-price?ids=bitcoin%2Cethereum&vs=usd

simulated — no real payment sent
/api/crypto-market$0.01

Rich market data: rank, volume, ATH, and more

  • ids= bitcoin,ethereum(required)
  • vs= usd

https://agentx402pay.com/api/crypto-market?ids=bitcoin%2Cethereum&vs=usd

simulated — no real payment sent
/api/crypto-trending$0.01

Top trending cryptocurrencies right now

No query params required.

https://agentx402pay.com/api/crypto-trending

simulated — no real payment sent
/api/web-search$0.015

Real ranked web search (Exa): title, URL, published date, relevance score

  • q= Base blockchain(required)
  • numResults= 5

https://agentx402pay.com/api/web-search?q=Base%20blockchain&numResults=5

simulated — no real payment sent
/api/prediction-arb$0.05

Same question priced differently on Polymarket and Kalshi, checked for matching outcome, numbers, dates and wording, with live quotes and hedge edge. No match, no charge.

  • q= election
  • limit= 10
  • minDivergencePct= 10

https://agentx402pay.com/api/prediction-arb?q=election&limit=10&minDivergencePct=10

simulated — no real payment sent

On-chain data

4

Multi-chain reads across Base, Ethereum, Polygon, Arbitrum, Optimism — balances, gas prices, ENS, and a safelisted read-only RPC proxy, all built on free public nodes.

/api/rpc$0.01

Safelisted read-only JSON-RPC proxy across five chains

eth_call, eth_getBalance, eth_blockNumber, and more

  • method= eth_blockNumber(required)
  • chain= base
  • params= []

https://agentx402pay.com/api/rpc?method=eth_blockNumber&chain=base&params=%5B%5D

simulated — no real payment sent
/api/wallet-balance$0.01

Native + optional ERC-20 token balance for any address

  • address= 0xd8dA...6045(required)
  • chain= base
  • token= 0x8335...0913

https://agentx402pay.com/api/wallet-balance?address=0xd8dA...6045&chain=base&token=0x8335...0913

simulated — no real payment sent
/api/gas-price$0.01

Current gas price + EIP-1559 fee estimate

  • chain= base

https://agentx402pay.com/api/gas-price?chain=base

simulated — no real payment sent
/api/ens-resolve$0.01

ENS name ⇄ address resolution

  • name= vitalik.eth

https://agentx402pay.com/api/ens-resolve?name=vitalik.eth

simulated — no real payment sent