Manifold

One interface. Many connections. Manifold.

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.

Engine manifold	This project
Single inlet	Requests from MCP clients
Distribution / routing	Protocol conversion / routing
To multiple cylinders	To multiple external MCP / REST APIs

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
MCP backend aggregation: Transparent reverse proxy to external MCP servers
Built-in OAuth 2.1 server: Authorization server with PKCE (S256) support
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: Connects to backends on first request (no backend dependency at gateway startup)
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.

Configuration

Place a configuration file (config.yaml) in the current directory or in a config/ subdirectory. Configuration values support environment variable expansion in the form ${VAR} or ${VAR:-default}.

Connecting to an MCP backend

Expose an external MCP server through Manifold.

gateway:
  port: 9999
  # openssl rand -base64 32
  encryptKey: ${ENCRYPT_KEY}

mcpServers:
  my-mcp-server:
    description: External MCP server
    transport: http
    url: http://localhost:8080/mcp

sqlite:
  path: ./tmp/manifold.db

manifold