MCP server that pays x402-gated HTTP endpoints — fetch, and on a 402 authorize, sign, retry
Quick Install
Automated & IDE SetupCopy the AI prompt to install this server into Claude Code, Cursor, or another agent — or use 1-click editor setup below.
One-click editor setup isn’t available for this listing yet — we don’t have a confirmed install command, and we’d rather show nothing than point your editor at the wrong package or host. Follow the project’s own setup instructions, linked above.
Manual Client & Custom JSON ConfigExpand JSON ▾
No confirmed setup config for this listing yet. We only publish a config block when the install details come from the project itself — its README, its docs, or a verified owner. We haven’t found those for mcp-x402-pay, and we’d rather show nothing than a guess you’d paste into your client. Follow the project’s own setup instructions for the current steps.
Documentation Overview
@cryptoapis-io/mcp-x402-pay
This is the BUYER side of x402 — the tool an agent uses to spend (pay for a resource). Merchants who want to charge for an API use the middleware SDK (
@cryptoapis-io/x402-merchant-sdk), not an MCP tool.
An MCP server that lets an AI agent find and pay x402-gated HTTP endpoints.
x402_pay— fetches a URL and, if the server returns402 Payment Required, authorizes the payment via the CryptoAPIs buyer service, signs locally, retries, and returns the paid response.x402_discover— browses the facilitator's catalogue of x402 resources and their prices, so an agent can find a paid API instead of only calling one it was handed.
Non-custodial: the private key is passed per request and never leaves the process (no HTTP server — stdio only).
Supported today: EVM (eip712, e.g. Base USDC) and Solana. Tron, Bitcoin/UTXO, XRP and Kaspa are
upcoming — wired but not yet enabled; paying on them returns a clear family_not_yet_supported
("coming soon") result.
Run
Prerequisite — an agent walletId
x402_pay pays from a CryptoAPIs agent wallet (walletId). Create one ONCE per blockchain+network
before paying — a single POST to the buyer API returns the id (non-custodial: you register only your
PUBLIC address):
network MUST be the CAIP-2 id (eip155:8453, solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp, …), not a
bare name — and exactly one of address (any chain; required for Solana/Kaspa) or xpub
(xpub-capable chains). A malformed body returns a clear 400 malformed_request. Set the returned id as
X402_WALLET_ID (or pass walletId).
Tool: x402_pay
| Input | Required | Description |
|---|---|---|
url | ✓ | the (possibly paywalled) resource |
apiKey | ✓ | your CryptoAPIs key (X402_BUYER feature) — only used to call the buyer /authorize |
walletId | ✓ | the wallet record id from POST /wallets (a registry _id) — NOT the on-chain address (an address gets wallet_not_found) |
privateKey | ✓ | the wallet's EVM key — signs locally, never sent anywhere |
method/body/headers | the request to make | |
allowedNetworks | restrict which CAIP-2 networks to pay on | |
maxAmount | safety cap — refuse if the required atomic-unit amount exceeds it | |
allowedHosts | restrict WHICH SITES may be paid, e.g. ["api.acme.com"] (leading dot = subdomains). A url outside the list is refused before any network call. Falls back to X402_ALLOWED_HOSTS (comma-separated) — pin it there to keep the allowlist outside the model's reach |
Returns { status, paid, body, settlement? }. On a 402 with no acceptable option (or over maxAmount),
paid:false with a reason — nothing is signed or paid.
Tool: x402_discover
Browse the x402 "Bazaar" — the registered x402 resources and what each charges (spec §8).
| Input | Required | Description |
|---|---|---|
type | filter by resource type, e.g. "http" | |
limit | page size, 1–100 (default 20) | |
offset | rows to skip, for paging (default 0) | |
facilitatorBaseUrl | override the facilitator (QA/local) |
Returns { resources: [{ resource, type, x402Version, accepts, lastUpdated, metadata? }], pagination }.
Public — no API key, no wallet, spends nothing, so it is always safe to call. Note accepts[].amount
is in atomic units (USDC 6-decimals: "10000" = $0.01) — convert before quoting a price to a user.
Pass a chosen resource to x402_pay to actually buy it.
Flow
fetch(url). Not 402 → return it.- 402 → pick an
acceptsentry (allowlist-aware), authorize via buyer/authorize→ the signing artifact. - Sign locally (
@cryptoapis-io/mcp-signerevm_signtyped-data) → build the x402PaymentPayload(wire scheme is alwaysexact; the family is innetwork). - Retry with the base64
X-PAYMENTheader; return the paid response + theX-PAYMENT-RESPONSEsettlement.
Security
The private key is a tool parameter and may be logged by MCP clients or stored in conversation
history — use only in trusted local environments. This mirrors @cryptoapis-io/mcp-signer.
Related MCP Servers
Reviews
No reviews yet — be the first to share how this listing worked for you.
Frequently Asked Questions about MCP X402 Pay
AllMCPs Directory Badge
Showcase your server listing on GitHub or your project documentation. Embed this dynamic SVG badge to highlight official listing status and live engagement.
Badge Style:
Live Dynamic SVG Preview
Markdown (GitHub README)
[](https://allmcps.com/mcp/mcp-x402-pay)HTML Embed
<a href="https://allmcps.com/mcp/mcp-x402-pay"><img src="https://allmcps.com/api/badge/mcp-x402-pay?style=directory" alt="MCP X402 Pay on AllMCPs" /></a>