MCP Front
Auth proxy for Model Context Protocol servers - adds authentication to MCP tools for Claude.ai, Claude Code, Cursor, Gemini
What is MCP Front?
MCP Front is a Model Context Protocol (MCP) server that allows AI assistants like Claude, Cursor, and VS Code to auth proxy for model context protocol servers - adds authentication to mcp tools for claude.ai, claude code, cursor, gemini
Auth proxy for Model Context Protocol servers - adds authentication to MCP tools for Claude.ai, Claude Code, Cursor, Gemini
This server falls under the Developer Tools category on MCPgee, the world's largest MCP server directory with 33,000+ servers.
Features
- Auth proxy for Model Context Protocol servers - adds authent
Use Cases
Maintainer
Works with
Installation
Manual Installation
npx mcp-frontConfiguration
Configuration Details
claude_desktop_config.json
Performance
Response Metrics
Resource Usage
How to Set Up and Use MCP Front
mcp-front is an authentication gateway written in Go that sits between Claude (or any MCP client) and your internal MCP servers. Without it, MCP servers have no built-in multi-user auth — you either expose them to the internet or run a separate instance per user. mcp-front solves this by adding OAuth 2.0 authentication (supporting Google, Azure AD, GitHub, and any OIDC provider) and per-user session isolation, so your whole team can securely use Claude against internal databases, APIs, and tools without modifying the MCP servers themselves. It proxies stdio, SSE, and streamable HTTP MCP backends and injects per-user API keys automatically for services like Notion or Linear.
Prerequisites
- Go 1.21 or later (for building from source), or Docker
- A domain with HTTPS configured (for production OAuth; localhost works for local development)
- An identity provider configured for OAuth — Google Workspace, Azure AD, GitHub, or any OIDC-compliant provider
- The MCP servers you want to protect already deployed and accessible from the mcp-front host
- An MCP-compatible client such as Claude.ai, Claude Desktop, Claude Code, or Cursor
Install mcp-front
Install via Go or pull the Docker image. For local development, the Go install is simplest.
# Via Go
go install github.com/stainless-api/mcp-front/cmd/mcp-front@main
# Or pull the Docker image
docker pull dgellow/mcp-front:latestCreate a config.json file
Define your proxy address, base URL, and the MCP servers to protect. For local testing you can use static bearer tokens instead of OAuth. The example below proxies the filesystem MCP server.
{
"version": "v0.0.1-DEV_EDITION_EXPECT_CHANGES",
"proxy": {
"baseURL": "http://localhost:8080",
"addr": ":8080"
},
"mcpServers": {
"filesystem": {
"transportType": "stdio",
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"],
"serviceAuths": [
{
"type": "bearer",
"tokens": ["dev-token-123"]
}
]
}
}
}Start mcp-front
Run the server pointing at your config file. In Docker mode mount the config as a volume.
# With Go binary
mcp-front -config config.json
# With Docker
docker run -p 8080:8080 \
-v $(pwd)/config.json:/app/config.json \
dgellow/mcp-front:latestAdd the mcp-front SSE endpoint to your MCP client
In Claude.ai or Claude Desktop, add a new MCP server with the SSE URL pointing to mcp-front, using the bearer token defined in your config.
{
"mcpServers": {
"filesystem-via-mcp-front": {
"url": "http://localhost:8080/filesystem/sse",
"headers": {
"Authorization": "Bearer dev-token-123"
}
}
}
}Configure OAuth for production
Replace the static bearer token auth with an OIDC provider block in config.json. Set your identity provider's issuer URL, client ID, and client secret. Users will be redirected to log in via your provider on first connection.
MCP Front Examples
Client configuration
MCP client config pointing at a locally running mcp-front instance with a static dev bearer token. In production, Claude will redirect to your OAuth provider instead of using a static token.
{
"mcpServers": {
"internal-tools": {
"url": "https://your-domain.com/filesystem/sse",
"headers": {
"Authorization": "Bearer your-team-token"
}
}
}
}Prompts to try
Once mcp-front is running and your backend MCP servers are proxied, use the same prompts you would use with those servers directly — mcp-front is transparent to the AI.
- "List the files in /tmp via the filesystem tool"
- "Read the contents of /tmp/notes.txt"
- "Which MCP tools are available through this connection?"
- "Create a file at /tmp/hello.txt with the text 'hello from Claude'"
- "Show me what tools are exposed by the internal-tools MCP server"Troubleshooting MCP Front
Claude connects to the SSE endpoint but immediately disconnects
Check that the bearer token in your MCP client's Authorization header matches one of the tokens in the serviceAuths section of your config.json. Token mismatches cause an immediate 401 which closes the connection.
The stdio MCP server subprocess fails to start
mcp-front runs the stdio server as a child process. Ensure the command (e.g. npx) is available in the PATH of the mcp-front process. When running in Docker, the target binary must also be installed inside the container.
OAuth redirect loop or 'organization not allowed' error
mcp-front validates that authenticated users belong to your configured organization or domain. Verify the allowedDomains or allowedOrganization field in your OIDC provider config matches your users' email domains exactly.
Frequently Asked Questions about MCP Front
What is MCP Front?
MCP Front is a Model Context Protocol (MCP) server that auth proxy for model context protocol servers - adds authentication to mcp tools for claude.ai, claude code, cursor, gemini It connects AI assistants to external tools and data sources through a standardized interface.
How do I install MCP Front?
Follow the installation instructions on the MCP Front GitHub repository. Clone the repo, install dependencies, and add the server config to your AI client.
Which AI clients work with MCP Front?
MCP Front works with all major MCP-compatible AI clients including Claude Desktop, Claude Code, Cursor, VS Code (GitHub Copilot), Windsurf, and Cline.
Is MCP Front free to use?
Yes, MCP Front is open source and available under the NOASSERTION license. You can use it freely in both personal and commercial projects.
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