x402 Universal Payer MCP server

by nirholas·io.github.nirholas/x402-bridge·v1.0.2

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Pay any x402 endpoint on the open web: auto-paying bridge with Bazaar discovery and spend caps.

B83/100grade B

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Safety scan

B83/100

full report

Adoption

Established

206 stars34 downloads/wk

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If you have run it, two minutes of your experience saves the next person an afternoon.

x402 Universal Payer tools (3)

write = sends, deletes, buys or posts

Read from the package source without running it. The installed server may list more.

call_paid_endpoint
Calls any HTTP URL that returns 402 with x402 payment requirements, automatically signing and paying.
list_bazaar_tools
Returns the cached list of x402 Bazaar resources registered as MCP tools on this bridge. Free: reads the in-process cache only, no network and no payment.
refresh_bazaar
Re-queries the x402 Bazaar discovery endpoint and re-registers dynamic tools. Use when new paid services have been added since the bridge started. Free (no payment), but mutates the bridge tool list and results vary with the live Bazaar.

Public scan report

scanner v0.1.9 · 2026-09-22 · same rubric, same numbers if you re-run it

no findings

Code scan9 source files scanned25/25
–Live reliabilityno gateway calls yet and no remote to proben/a
–Tool poisoningtools not inspected (local package is not executed); not countedn/a
Auth qualitystatic API keys via environment variables6/15
Maintenancelast push 0 days ago15/15
Maintainer identityregistry namespace matches repository owner; GitHub account older than a year8/10

Overall 83/100. Components that don't apply are left out of the denominator. Any critical finding is an F.Rubric Appeal a finding JSON

What the publisher says

From the x402 Universal Payer repository's README, as published. We do not edit it. Read it on GitHub

three.ws

Website · Docs · Changelog · X / Twitter · GitHub · $THREE on pump.fun

https://github.com/user-attachments/assets/d52515d1-cb04-4dd6-98bd-fef233312dc4

Give your AI a body. three.ws is an open source (Apache-2.0), browser-native 3D AI agent platform. Type a prompt and Forge generates a textured 3D model, or drop a GLB you already have. Add an LLM brain, register on-chain, and embed anywhere: no plugins, no server uploads, no installs required.

Try it in 60 seconds: open three.ws/forge, type "a brass steampunk owl, full body", and download the GLB. Text→3D, image→3D, and sketch→3D — free draft tier, no account. Jump to the Forge section ↓

Want to build it with us? Your first contribution goes from clone to open pull request in about 15 minutes, with a full worked example. Every good first issue names the file to change and the command that proves it worked. Say hello in Discussions or Telegram.

Meet the avatar: a live 3D model, right here in markdown

Drag to rotate. This is not an image or a video: it is an interactive 3D model rendered natively by GitHub. The avatar was generated from a one-line text prompt on three.ws Forge (free tier), decimated to 1,200 triangles, and embedded as ASCII STL with readme-3d, our open-source toolkit for putting 3D models in any GitHub README, issue, or discussion.

Shortened. The full README is on GitHub.

Nothing above is checked by us. What we check is on the safety report.

Install directly

Runs npx -y @three-ws/mcp-bridge on your machine. Read the scan report first; the gateway never runs local packages.

claude mcp add x402-bridge -- npx -y @three-ws/mcp-bridge

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x402 Universal Payer: common questions

Is x402 Universal Payer MCP server safe?: Mostly: it is graded B (83/100). Read the x402 Universal Payer safety report
How do I install x402 Universal Payer?: It runs on your machine. Copy the Claude Code, Claude Desktop or Cursor config from the install section.
Does x402 Universal Payer need an API key?: Yes. The registry entry asks for MCP_BRIDGE_EVM_PRIVATE_KEY, MCP_BRIDGE_SVM_PRIVATE_KEY.
Is x402 Universal Payer maintained?: The last commit was in the last day (2026-09-22). The latest release is v1.0.2.

Run it through the gateway

Local package. It runs on your machine, not through the gateway.

Rating: —
Safety grade: B · 83/100
Stars: 206
Downloads/wk: 34
Price: Free
Licence: Apache-2.0
Transport: Local · npm
Version: 1.0.2
Category: Everything else
Last release: 2026-09-22

Credentials it needs

MCP_BRIDGE_EVM_PRIVATE_KEYsecret0x-prefixed 32-byte hex private key that funds USDC payments on EVM chains (Base, Arbitrum, …). At least one of the EVM/SVM keys is required. Treat like cash — use a dedicated low-balance wallet.
MCP_BRIDGE_SVM_PRIVATE_KEYsecretSolana secret key that funds USDC payments: base58 64-byte secret key (Phantom / solana-keygen format) or a JSON array of 64 integers. At least one of the EVM/SVM keys is required. Treat like cash.
MCP_BRIDGE_MAX_PRICE_PER_CALL_ATOMICPer-call spending cap in atomic units (USDC has 6 decimals). Payments above this abort with a clear reason.
MCP_BRIDGE_MAX_TOTAL_ATOMICCumulative session spending ceiling in atomic units. Once total spend would exceed it, further payments abort until restart.
MCP_BRIDGE_ALLOWED_PAYTOComma-separated payee allowlist. When set, any payment whose payTo address is not listed is refused.
MCP_BRIDGE_ALLOWED_HOSTSComma-separated hostname allowlist for outbound paid requests. When set, any other host is refused before a request is signed.
MCP_BRIDGE_ALLOW_HTTPSet to 1 to allow http:// targets (local development only). https is enforced otherwise.
MCP_BRIDGE_DISCOVER_LIMITMax number of x402 Bazaar resources to register as dynamic tools at startup. Set 0 to disable discovery.
MCP_BRIDGE_BAZAAR_URLx402 Bazaar discovery endpoint. Override to point at a self-hosted or alternative bazaar.
MCP_BRIDGE_BATCH_DEPOSIT_MULTIPLIERHow many request-amounts to deposit at once when opening an EVM batch-settlement channel.
MCP_BRIDGE_MAX_DEPOSIT_ATOMICHard cap in atomic units on a single batch-settlement channel deposit or top-up.
X402_MCP_BRIDGE_CHANNELS_DIRDirectory for persisted batch-settlement channel state (survives client restarts).
RPC_URL_8453Per-chain RPC override, one variable per chain id (RPC_URL_<chainId>, e.g. RPC_URL_8453 for Base). Defaults to viem's public RPC for that chain.

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