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CaptchaAI MCP Server

CaptchaAI MCP Server

Official
by CaptchaAI

CaptchaAI MCP Server

Official Model Context Protocol (MCP) server for CaptchaAI, built with FastMCP and backed by the official captchaai Python SDK.

Exposes token-mode (pure API, no browser required) tools so AI assistants and automation agents can inspect account capacity, check supported CAPTCHA types, and solve challenges.

Tools

Tool

Description

API Key Needed

get_supported_captchas

List the 8 token-mode CAPTCHA types with required/optional arguments and proxy/UA notes

No

get_threads

Get account thread usage (threads, working_threads, free_threads)

Yes

get_balance

Get account balance string (balance)

Yes

solve_captcha

Solve a CAPTCHA in token mode and return task_id, solution, and user_agent

Yes

Related MCP server: captchaflow

Supported captcha_type Values

  • recaptcha_v2 (supports invisible=True and enterprise=True)

  • recaptcha_v3 (requires action; supports enterprise=True and min_score)

  • turnstile

  • cloudflare_challenge (requires proxy + proxytype ("HTTP" or "HTTPS"); returns user_agent)

  • geetest (requires gt + challenge; returns {challenge, validate, seccode})

  • captchafox (requires proxy + proxytype ("HTTP" or "HTTPS"); returns user_agent)

  • friendly_captcha

  • lemin (requires captcha_id + div_id; returns {answer, challenge_uuid})

Installation

Install directly from PyPI with pip or run via uvx:

pip install captchaai-mcp

Or run from a local clone:

git clone https://github.com/CaptchaAI/captchaai-mcp.git
cd captchaai-mcp
uv sync

Set your API key:

export CAPTCHAAI_API_KEY="YOUR_32_CHAR_API_KEY"

Running

# STDIO (default — for Claude Desktop, Cursor, Windsurf, etc.)
uvx captchaai-mcp
# or from source:
uv run captchaai-mcp

# Streamable HTTP (serves at http://127.0.0.1:8000/mcp)
uvx captchaai-mcp --transport streamable-http --host 127.0.0.1 --port 8000
NOTE

PreferCAPTCHAAI_API_KEY in the environment over --api-key on multi-user hosts so the key is not visible in process listings. When using --transport streamable-http, bind to loopback or place it behind an authenticating TLS reverse proxy.

MCP Client Configuration

See the full MCP Client Integration Guide for step-by-step setup with Claude Code, OpenAI Codex CLI, Cursor, Claude Desktop, VS Code, Windsurf, and Antigravity.

Using uvx (recommended):

{
  "mcpServers": {
    "captchaai": {
      "command": "uvx",
      "args": ["captchaai-mcp"],
      "env": {
        "CAPTCHAAI_API_KEY": "YOUR_32_CHAR_API_KEY"
      }
    }
  }
}

Or from a local checkout:

{
  "mcpServers": {
    "captchaai": {
      "command": "uv",
      "args": [
        "run",
        "--directory",
        "/path/to/captchaai-mcp",
        "captchaai-mcp"
      ],
      "env": {
        "CAPTCHAAI_API_KEY": "YOUR_32_CHAR_API_KEY"
      }
    }
  }
}

Development & Tests

# Run MCP server tests
uv run pytest -q

# Inspect the MCP server manifest
uv run fastmcp inspect src/captchaai_mcp/server.py:create_server

License

MIT — see LICENSE.

Available Tools

4 tools
get_balanceGet BalanceA
Read-only

Get the CaptchaAI account balance as returned by the API.

Inputs: no named parameters. Returns: object

get_supported_captchasGet Supported CaptchasA
Read-onlyIdempotent

List all supported token-mode CAPTCHA types with required/optional arguments and capabilities.

Works without an API key.

Inputs: no named parameters. Returns: object

get_threadsGet ThreadsA
Read-only

Get CaptchaAI thread usage: total threads, active working_threads, and free_threads.

Inputs: no named parameters. Returns: object

solve_captchaSolve CaptchaA

Solve a CAPTCHA in token mode (no browser) and return the solved token or payload.

Blocks until solved (typically 10-80s). Call get_supported_captchas() first to check which arguments are required for the chosen captcha_type. When user_agent is returned (Enterprise, Cloudflare Challenge, CaptchaFox), reuse it when submitting the token.

Inputs: website_url (required), captcha_type (required), gt, proxy, +13 more. Returns: object

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

Loading tool schema changelog…

    TDQS

    A3.9/5.0

    Scored across 4 tools

    Disambiguation5/5

    Each tool targets a distinct concern: two account-metric reads (threads vs. balance), one capability-discovery call, and one solve action. The descriptions make clear what each returns (working_threads/free_threads vs. monetary balance), and solve_captcha is unmistakably the only action tool. No two tools can plausibly be swapped.

    Naming Consistency5/5

    All four names follow a strict verb_noun snake_case pattern: get_threads, get_balance, get_supported_captchas, solve_captcha. The get_* reads and the solve_* action are predictable, and a new tool would obviously be named by the same convention.

    Tool Count4/5

    Four tools is a tight, purposeful surface for a narrow service (discover types, solve, check capacity, check balance). It is at the low end of the comfortable 3-15 range, and a small amount of padding (e.g., a combined account-status or error-lookup tool) would round it out, but nothing here feels redundant.

    Completeness4/5

    The core lifecycle is covered: get_supported_captchas to discover required args, then solve_captcha, with get_threads/get_balance for capacity and billing. Minor gaps exist around failure handling — no way to poll/retrieve a timed-out or asynchronous solve, and no reporting of failed solves — but the primary workflow has no dead ends.

    Maintenance

    ActivityMaintained
    ResponsivenessNo recent community issues

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