Manifold MCP server

Manifold

One interface. Many connections. Manifold.

English | 日本語

Manifold is a gateway that acts as an MCP server while connecting to multiple external MCP servers and OpenAPI / Swagger-compliant REST APIs on the backend.

Why "Manifold"?

The name Manifold comes from an engine's intake manifold.

An intake manifold is the component that distributes air and fuel evenly and efficiently from a single inlet to multiple cylinders. We named this project Manifold because its structure is similar.

Architecture

MCP Client
    │
    ▼
┌─────────────┐
│   Manifold  │   ← this server
└─────────────┘
    │       │
    ▼       ▼
External  OpenAPI / Swagger
MCP       REST API Server
Server

Features

• OpenAPI / Swagger → MCP conversion: Automatically generates MCP tools from OpenAPI 3.x / Swagger 2.x specifications
• Static tool catalog: Inspect the MCP tools an OpenAPI spec would generate before starting the gateway (manifold openapi tools), and start from a committed, diffable generated file instead of fetching the spec at boot (manifold openapi generate, mcpServers..tools.file)
• MCP backend aggregation: Transparent reverse proxy to external MCP servers
• Built-in OAuth 2.1 server: Authorization server with PKCE (S256) support. Downstream clients register through DCR (RFC 7591) or a client ID metadata document (CIMD), and can be mapped one-to-one onto upstream OAuth clients
• Pluggable backend authentication: Choose one of static header (authValue) / OAuth 2.0 (oauth2) / API key Token Exchange (tokenExchange)
• Resource links: Stores binary content from tool responses in S3 and returns download URLs (resource links)
• Lazy connection (stdio) / stateless connection (http): stdio backends connect on first request (no backend dependency at gateway startup); http backends open a fresh connection per request and never share a session across callers
• Selectable storage: Session / token management backed by Redis or SQLite
• OpenTelemetry support: OTLP export of traces, metrics, and logs (metrics also support Prometheus-style pull)

Requirements

• Go 1.26+
• Redis or SQLite (for session management)

Installation

Download binary

Download the latest binary from Releases.

Build from source

git clone https://github.com/nonchan7720/manifold.git
cd manifold
go build -o manifold .

Docker

docker pull ghcr.io/nonchan7720/manifold:latest

Usage

Start the gateway

# Run the binary
manifold gateway

# Specify a config file explicitly (-c / --config, config name without extension)
manifold gateway -c config

# Run from source
go run main.go gateway

# Docker (working directory is /home/nonroot)
docker run -p 9999:9999 \
  -v $(pwd)/config.yaml:/home/nonroot/config.yaml \
  ghcr.io/nonchan7720/manifold:latest

Docker Compose (development)

Starts a development environment including Redis.

docker compose up -d

Ready-to-run configuration examples are available in the examples/ directory.

Inspect and generate MCP tools

Shortened. The full README is on GitHub.