x402 Universal Payer MCP Server

Connect this server

This server runs on your own machine — install it with the package manager and the client starts it for you. Package name taken from the official registry entry.

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

{
  "mcpServers": {
    "x402-bridge": {
      "command": "npx",
      "args": [
        "-y",
        "@three-ws/mcp-bridge"
      ]
    }
  }
}

[mcp_servers.x402-bridge]
command = "npx"
args = ["-y", "@three-ws/mcp-bridge"]

{
  "mcpServers": {
    "x402-bridge": {
      "command": "npx",
      "args": [
        "-y",
        "@three-ws/mcp-bridge"
      ]
    }
  }
}

{
  "servers": {
    "x402-bridge": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@three-ws/mcp-bridge"
      ]
    }
  }
}

Optional settings from the registry entry, left out of the block above: MCP_BRIDGE_EVM_PRIVATE_KEY (0x-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_KEY (Solana 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_ATOMIC (Per-call spending cap in atomic units (USDC has 6 decimals). Payments above this abort with a clear reason), MCP_BRIDGE_MAX_TOTAL_ATOMIC (Cumulative session spending ceiling in atomic units. Once total spend would exceed it, further payments abort until restart), MCP_BRIDGE_ALLOWED_PAYTO (Comma-separated payee allowlist. When set, any payment whose payTo address is not listed is refused), MCP_BRIDGE_ALLOWED_HOSTS (Comma-separated hostname allowlist for outbound paid requests. When set, any other host is refused before a request is signed), MCP_BRIDGE_ALLOW_HTTP (Set to 1 to allow http:// targets (local development only). https is enforced otherwise), MCP_BRIDGE_DISCOVER_LIMIT (Max number of x402 Bazaar resources to register as dynamic tools at startup. Set 0 to disable discovery), MCP_BRIDGE_BAZAAR_URL (x402 Bazaar discovery endpoint. Override to point at a self-hosted or alternative bazaar), MCP_BRIDGE_BATCH_DEPOSIT_MULTIPLIER (How many request-amounts to deposit at once when opening an EVM batch-settlement channel), MCP_BRIDGE_MAX_DEPOSIT_ATOMIC (Hard cap in atomic units on a single batch-settlement channel deposit or top-up), X402_MCP_BRIDGE_CHANNELS_DIR (Directory for persisted batch-settlement channel state (survives client restarts)), RPC_URL_8453 (Per-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).