How do I install HTTPayer?

Copy the stdio config for Cursor, Claude Desktop, Claude Code, or VS Code on this page. It uses the publisher's install, not a PlugMCP proxy.

Does HTTPayer need an API key?

No required environment variable is listed on this record.

What transport does HTTPayer use?

HTTPayer runs locally over stdio.

When was HTTPayer last checked?

Last checked 2026-11-09. x402 micropayments for AI agents — credits-based, no wallets, no blockchain.

HTTPayer MCP server

Power your agent

Add this server

The publisher's own command. Not a PlugMCP endpoint.

Add to Cursor Add to VS Code Run on PlugMCP

Host a copy with our keys and logs.

Local command

npx -y @httpayer/[email protected]

Claude Code has no install link for a local command. Copy the command below and run it in a terminal.

shClaude Code

1claude mcp add io.github.httpayer-mcp -- npx -y @httpayer/mcp@0.1.7

Run in a terminal.

jsonClaude Desktop

1{2  "mcpServers": {3    "io.github.httpayer-mcp": {4      "command": "npx",5      "args": [6        "-y",7        "@httpayer/[email protected]"8      ]9    }10  }11}

claude_desktop_config.json

Local · npmPublisher installStep-by-step: add this in Claude

Remote URL or a command on your machine? How the two installs differ

Run on PlugMCP

Host a copy with our keys and logs.

A new server you create. It is not this listing's official endpoint. Use the publisher install when you want their URL and their credentials.

Launch

Server facts

Local

Transport: stdio
Version: 0.1.7
Last checked

Tools

No tool list yet. Remote servers get one after the first health check.

FAQ

Questions

@httpayer/mcp

MCP (Model Context Protocol) server for HTTPayer. Lets AI agents call x402-enabled APIs using credit balance — no wallets, no blockchain, no Web3 knowledge required.

Dashboard & API keys: app.httpayer.com
npm: @httpayer/mcp
GitHub: httpayer/mcp

Quickstart

With an AI agent (recommended)

Paste this into any MCP-compatible agent (Claude Code, Cursor, Windsurf, OpenCode...):

Set up https://httpayer.com/skill.md

The agent detects your environment and handles everything automatically.

Without an agent (manual)

1. Run setup:

npx @httpayer/mcp setup

Get your API key at app.httpayer.com when prompted.

Flags:

Flag	Description
`--key sk-live-...`	Provide key non-interactively
`--client <name>`	Target client: `claude-code`, `claude-desktop`, `cursor`, `windsurf`, `opencode`, `zed`, `cline`, `warp`, `codex`
`--scope user\|project`	Claude Code scope (default: `user`)
`--yes` / `-y`	Skip all prompts
`--update-key`	Replace existing key

2. Add to your client:

Claude Code:

claude mcp add httpayer --scope user -- npx -y @httpayer/mcp@latest

Claude Desktop (~/Library/Application Support/Claude/claude_desktop_config.json on macOS, %APPDATA%\Claude\claude_desktop_config.json on Windows):

{
  "mcpServers": {
    "httpayer": {
      "command": "npx",
      "args": ["-y", "@httpayer/mcp@latest"]
    }
  }
}

Cursor (.cursor/mcp.json), Windsurf (.windsurf/mcp.json), Cline (.cline/mcp_settings.json):

{
  "mcpServers": {
    "httpayer": {
      "command": "npx",
      "args": ["-y", "@httpayer/mcp@latest"]
    }
  }
}

OpenCode (opencode.json or ~/.config/opencode/config.json):

{
  "mcp": {
    "httpayer": {
      "type": "local",
      "command": ["npx", "-y", "@httpayer/mcp@latest"],
      "enabled": true
    }
  }
}

Zed:

{
  "context_servers": {
    "httpayer": {
      "command": {
        "path": "npx",
        "args": ["-y", "@httpayer/mcp@latest"]
      }
    }
  }
}

3. Restart your client and verify:

Ask your agent: "fetch https://api.httpayer.com/demo/v1/base-weather"

A weather response means HTTPayer is working.

How it works

User prompt
    │
    ▼
AI agent (Claude Code, Cursor, Windsurf...)
    │  uses MCP tools + prompts + resources
    ▼
@httpayer/mcp (local MCP server via npx)
    │  REST calls with x-api-key header
    ▼
api.httpayer.com
    │  proxy handles x402 payment to target
    ▼
Target x402-gated API

Runtime flow

Your client launches the MCP server via npx -y @httpayer/mcp@latest on startup (stdio transport).
The server reads the API key from ~/.httpayer/mcp-config.json.
The agent receives the tool list, system instructions, prompts, and resources in its context.
When the agent calls fetch, the MCP server forwards the request to POST https://api.httpayer.com/proxy.
HTTPayer's proxy detects a 402, pays using your credits, retries, and returns the final response.
The result (status, body, headers) comes back to the agent.

MCP capabilities

This server exposes three MCP primitives so agents get context automatically — without the user having to ask.

Tools

Six tools (see full reference below).

Prompts

Name	Description
`httpayer-context`	Injects full HTTPayer payment context into the agent. Clients that support prompts will load this automatically at session start.

Compatible clients (Claude Desktop, Cursor, and others) call prompts/list on connection and inject these into the agent's context proactively.

Resources

URI	Description
`httpayer://skill.md`	Full setup guide, trigger patterns, available endpoints, and workflow. Clients can pull this on demand as grounding context.

MCP tools reference

`get_balance`

Check credit balance and daily usage.

Input: none

Example response:

{
  "account_id": "account_123",
  "mainnet": {
    "credits_balance": 50000,
    "daily_limit": 100000,
    "daily_spend": 15500,
    "daily_remaining": 84500
  }
}

`fetch`

Make an HTTP request to any x402-enabled endpoint. Payment is handled automatically.

Input:

Field	Type	Required	Description
`url`	string	yes	Target URL
`method`	string	no	`GET`, `POST`, `PUT`, `DELETE`, `PATCH` — default `GET`
`body`	object	no	JSON request body
`params`	object	no	Query string parameters
`headers`	object	no	Additional request headers
`timeout`	number	no	Timeout in seconds, max 120

Example response:

{
  "status": 200,
  "body": { "data": "..." },
  "headers": { "content-type": "application/json" }
}

On 502, the response includes webhook_id for async polling.

`simulate`

Dry-run a fetch. Returns cost estimate without spending credits.

Input: Same as fetch (except timeout).

Example response:

{
  "requiresPayment": true,
  "proxyFeeBreakdown": {
    "targetAmount": 0.01,
    "proxyFee": 0.0003,
    "totalCreditsCharged": 10.3
  }
}

`get_topup_link`

Returns the dashboard URL to add credits. Show to user when balance is low.

Input: none

`check_limits`

Check global HTTPayer system daily limits and remaining capacity.

Input: none

`get_webhook_status`

Poll the status of an async operation. Use when fetch returns a 502 with webhook_id.

Input: webhook_id (string, required)

Status values: pending, success, success_refunded, payment_failed, upstream_error, internal_error, rate_limited

HTTPayer API reference

Authentication: x-api-key: sk-live-... header on all requests.

Method	Path	Tool
`GET`	`/v1/credits/balance`	`get_balance`
`POST`	`/proxy`	`fetch`
`POST`	`/proxy/sim`	`simulate`
`GET`	`/limits`	`check_limits`
`GET`	`/webhooks/{id}`	`get_webhook_status`

Proxy endpoint

POST https://api.httpayer.com/proxy

{
  "api_url": "https://target.example.com/endpoint",
  "method": "GET",
  "json": { "key": "value" },
  "params": { "query": "param" },
  "headers": { "Custom-Header": "value" },
  "timeout": 30
}

Only api_url and method are required.

Status codes:

Code	Meaning
`200`	Success
`402`	Insufficient credits
`429`	Rate limited
`500`	Proxy error
`502`	Target refused payment — includes `webhook_id`

Configuration

API key stored at: ~/.httpayer/mcp-config.json

{ "apiKey": "sk-live-..." }

To update: npx @httpayer/mcp setup --update-key

x402 protocol overview

x402 is an HTTP-native micropayment protocol using the 402 Payment Required status code.

Without HTTPayer:

Client hits endpoint → gets 402 + payment requirements
Client pays on-chain (requires wallet + USDC)
Client retries with payment proof

With HTTPayer:

Client calls POST /proxy { api_url, method, ... }
HTTPayer detects 402, pays using your credits
HTTPayer retries and returns the final response

All blockchain interaction happens on HTTPayer's side.

Credit system

Unit	Value
1 credit	0.001 USDC
1 USDC	1,000 credits
Proxy fee	3% of target payment

Top up at app.httpayer.com. Below 100 credits, the agent will prompt you to top up.

Error handling

Setup errors

Situation	Behavior
Key format invalid	Print error, exit 1
Key rejected (401)	Print "API key rejected", exit 1
Network unreachable	Print reason, exit 1

MCP tool errors

All errors return isError: true — the server stays alive and the agent gets a readable message.

Situation	Message
No config	`"No HTTPayer API key configured. Run: npx @httpayer/mcp setup"`
API non-2xx	`"HTTPayer {status}: {body}"`
Unknown tool	`"Unknown tool: {name}"`

Add this server

Host a copy with our keys and logs.

Server facts

Tools

Questions

How do I install HTTPayer?

Does HTTPayer need an API key?

What transport does HTTPayer use?

When was HTTPayer last checked?

Documentation

@httpayer/mcp

Quickstart

With an AI agent (recommended)

Without an agent (manual)

How it works

Runtime flow

MCP capabilities

Tools

Prompts

Resources

MCP tools reference

get_balance

fetch

simulate

get_topup_link

check_limits

get_webhook_status

HTTPayer API reference

Proxy endpoint

Configuration

x402 protocol overview

Credit system

Error handling

Setup errors

MCP tool errors

`get_balance`

`fetch`

`simulate`

`get_topup_link`

`check_limits`

`get_webhook_status`