Link Finder MCP

An MCP server for the Link Finder API — find backlink opportunities, analyze competitors, discover similar domains with AI embeddings, and manage prospecting projects directly from Claude, ChatGPT, Cursor, or any MCP client.

Secrets are provided only through environment variables, and the server is host-agnostic: run it locally over stdio, or deploy it anywhere (Render or any VM) with a bearer-token-protected HTTP/SSE endpoint.

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Features

All Link Finder API v2 endpoints are exposed as tools:

Tool	Endpoint	Plan	What it does
get_account	getAccount	Booster	Plan, remaining credits, available features
list_platforms	listPlatforms	Booster	Supported netlinking platforms
list_locations	listLocations	Booster	Countries/locations for keyword search
keyword_search	kwSearch	Booster	Find opportunities from keywords (SERP analysis)
competitor_analysis	competitor	Booster	A competitor's available referring domains
ai_search	aiSearch	Booster	AI prospecting with relevance scoring
similar_domains	similarDomains	Booster	AI-embedding lookalike domains (the gem finder)
create_project	createProject	Booster	Create a project
list_projects	listProjects	Booster	List projects with counts
project_favorites	projectFavorites	Booster	Favorites in a project with full metrics
add_favorite	addFavorite	Booster	Add / remove a domain from a project
update_note	updateNote	Booster	Annotate a standout favorite
check_domain	checkDomain	API	Check one domain across all platforms
bulk_check	bulk	API	Check up to 50,000 domains at once
get_search_history	local	—	Read locally saved search history

Plus a guided prompt backlink_workflow that runs the step-by-step interview and prospecting flow.

The server also follows the API's best practices: every search result is saved locally to a data/ folder and logged in data/searchHistory.json so agents can avoid duplicate, credit-wasting searches.

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Requirements

• Python 3.10+
• A Link Finder API key — get it in your account at https://app.link-finder.net/account/ (Booster plan or higher; checkDomain and bulk need the API plan)

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Installation

git clone https://github.com/<you>/link-finder-mcp.git
cd link-finder-mcp

python -m venv .venv && source .venv/bin/activate    # optional but recommended
pip install -r requirements.txt

Copy the example environment file and fill in your key:

cp .env.example .env
# then edit .env and set LINK_FINDER_API_KEY

No credentials in code. The API key is read only from LINK_FINDER_API_KEY and is never accepted as a tool argument, so it can't leak through the model context.

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Configuration

All configuration is via environment variables:

Variable	Required	Default	Description
LINK_FINDER_API_KEY	yes	—	Your Link Finder API key
MCP_TRANSPORT	no	stdio	stdio (local), http (Streamable HTTP, recommended for hosting), or sse (legacy)
MCP_BEARER_TOKEN	hosted only	—	Shared secret clients send as Authorization: Bearer <token>
PORT	no	8000	Port to bind in hosted mode (Render/Railway/Fly inject this)
HOST	no	0.0.0.0	Bind address in hosted mode
MCP_STATELESS_HTTP	no	true	Streamable HTTP only. Stateless = no per-session server state; robust behind proxies/load balancers
MCP_JSON_RESPONSE	no	false	Streamable HTTP only. true returns plain JSON instead of SSE-framed responses (only if your client requires it)
LINK_FINDER_DATA_DIR	no	data	Where results + history are saved (empty = disable)
LINK_FINDER_BASE_URL	no	https://app.link-finder.net/api/v2	Override the API base URL
LINK_FINDER_HTTP_TIMEOUT	no	120	HTTP timeout in seconds
MCP_ALLOWED_HOSTS	no	(empty)	Comma-separated Host allowlist for DNS-rebinding protection. Empty = disabled (works behind any proxy). Supports a :* port wildcard.
MCP_ALLOWED_ORIGINS	no	(empty)	Comma-separated Origin allowlist (used with the above).

Which transport?

• Local clients (Claude Desktop, Cursor, ...) → stdio.
• Hosted (Render or any VM) → http (Streamable HTTP). This is the recommended, proxy-friendly transport; the endpoint lives at /mcp.
• sse is the older transport (endpoint at /sse). It works, but long-lived SSE streams can be buffered or reset by PaaS proxies, which can stall the MCP initialization handshake. Prefer http unless your client only speaks SSE.

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Running locally (stdio)

export PYTHONPATH=src
python -m link_finder_mcp.server

Or debug interactively with the MCP Inspector:

PYTHONPATH=src mcp dev src/link_finder_mcp/server.py

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Use with Claude Desktop

Edit your Claude config:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "link-finder": {
      "command": "python",
      "args": ["-m", "link_finder_mcp.server"],
      "env": {
        "PYTHONPATH": "/absolute/path/to/link-finder-mcp/src",
        "MCP_TRANSPORT": "stdio",
        "LINK_FINDER_API_KEY": "your_link_finder_api_key_here",
        "LINK_FINDER_DATA_DIR": "/absolute/path/to/link-finder-mcp/data"
      }
    }
  }
}

Restart Claude Desktop. You'll see the Link Finder tools under the tools (hammer) icon. Try:

"Check my Link Finder credits, then find French backlink opportunities for the keywords assurance auto;comparateur assurance with DR 20+ and 500+ traffic. Save the best ones to a new project called Assurance Q3."

Claude will chain get_account → keyword_search → create_project → add_favorite, then suggest similar_domains on the top matches.

Tip: in Claude Desktop you can also attach the backlink_workflow prompt (the "+" / prompts menu) to launch the full guided interview.

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Use with ChatGPT

ChatGPT supports remote MCP servers (Developer mode / custom connectors and the Responses API tools of type mcp). For that you need the server reachable over HTTPS with a bearer token — see Deploy on Render.

Option A — ChatGPT Developer Mode / Connectors (UI)

1. Deploy the server (e.g. on Render) with MCP_TRANSPORT=http and a strong MCP_BEARER_TOKEN.
2. In ChatGPT: Settings → Connectors → Advanced → Developer mode, then Create a connector.
3. Set the server URL to your deployment's MCP endpoint, e.g. https://your-app.onrender.com/mcp.
4. Add an Authorization header: Bearer <your MCP_BEARER_TOKEN>.
5. Save, then enable the connector in a chat and ask it to find backlinks.

Option B — OpenAI Responses API (programmatic)

from openai import OpenAI

client = OpenAI()

resp = client.responses.create(
    model="gpt-4.1",
    tools=[
        {
            "type": "mcp",
            "server_label": "link-finder",
            "server_url": "https://your-app.onrender.com/mcp",
            "headers": {"Authorization": "Bearer YOUR_MCP_BEARER_TOKEN"},
            "require_approval": "never",
        }
    ],
    input="Use Link Finder to find Spanish (language 2724) backlink "
          "opportunities for 'hosting wordpress' with TF 15+ and report a table.",
)

print(resp.output_text)

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Use with Cursor

Add to ~/.cursor/mcp.json (or the project .cursor/mcp.json):

{
  "mcpServers": {
    "link-finder": {
      "command": "python",
      "args": ["-m", "link_finder_mcp.server"],
      "env": {
        "PYTHONPATH": "/absolute/path/to/link-finder-mcp/src",
        "LINK_FINDER_API_KEY": "your_link_finder_api_key_here"
      }
    }
  }
}

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Deploy on Render (or any VM)

The server is host-agnostic. In hosted mode it binds 0.0.0.0:$PORT and protects the MCP endpoints with a bearer token. The recommended hosted transport is Streamable HTTP (MCP_TRANSPORT=http), served at /mcp.

A ready-made render.yaml is included:

services:
  - type: web
    name: link-finder-mcp
    runtime: python
    buildCommand: pip install -r requirements.txt
    startCommand: python -m link_finder_mcp.server
    envVars:
      - key: PYTHONPATH
        value: src
      - key: MCP_TRANSPORT
        value: http
      - key: LINK_FINDER_API_KEY
        sync: false
      - key: MCP_BEARER_TOKEN
        sync: false

1. Push this repo to GitHub.
2. In Render: New → Blueprint, point it at the repo.
3. Set the two secret env vars (LINK_FINDER_API_KEY, MCP_BEARER_TOKEN) in the dashboard.
4. Deploy. Your MCP endpoint will be https://<service>.onrender.com/mcp.

The same works on any VM / PaaS — just set the env vars and run python -m link_finder_mcp.server. Set MCP_TRANSPORT=sse (endpoint /sse) only if your client requires the legacy SSE transport.

Point your client at the /mcp endpoint with the bearer token:

{
  "url": "https://your-app.onrender.com/mcp",
  "headers": { "Authorization": "Bearer YOUR_MCP_BEARER_TOKEN" }
}

Note on saved data: on ephemeral hosts (like Render's default disk) the data/ folder is not persistent. Mount a persistent disk, or set LINK_FINDER_DATA_DIR to a mounted path, if you want the search history to survive restarts. Local (stdio) usage persists normally.

Troubleshooting

• Failed to validate request: Received request before initialization was complete (repeating, on SSE) — the MCP initialize handshake is stalling. With the legacy SSE transport the initialize response travels back over the long-lived GET /sse stream, and PaaS proxies (Render included) often buffer or reset that stream so it never reaches the client. Fix: use MCP_TRANSPORT=http (Streamable HTTP, endpoint /mcp), which doesn't depend on a persistent stream and runs stateless by default.
• SSE error: Non-200 status code (421) / Invalid Host header — this is DNS-rebinding protection rejecting the proxy's public hostname. The server disables host checking by default (the bearer token already guards it), so a fresh deploy works out of the box. If you set MCP_ALLOWED_HOSTS, make sure it includes your public host, e.g. your-app.onrender.com.
• GET / → 404 / POST <path> → 405 in the logs — harmless. Each transport serves on its own path (/mcp for Streamable HTTP, /sse + /messages/ for SSE); probes hitting other paths/methods are expected. Point your client at the right path for your transport.

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How credits work

• Credits are shared across the web app, browser extension, and API.
• keyword_search costs 1 keywords_search credit per keyword; competitor_analysis 1 per request; ai_search 1 per request; similar_domains 1 per domain (or per project search).
• Credits are only consumed when results are found.
• Always call get_account first to check remaining credits and which features your plan unlocks.

Reading results

Each domain result includes fields you can filter and sort on: title, domain, dr (Ahrefs), tf/cf (Majestic), rd, traffic, ttf0 (topic), ai_lang, gg_news, and per-platform prices (-2 = not found, -1 = price unavailable, >0 = price in the chosen currency). Each platform also has a _url field with the direct purchase link, and best_price_platform names the cheapest one.

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License

MIT — see LICENSE.