v1.3.0 Apache-2.0 40/40 MCP conformant

The enterprise MCP gateway.

One governed endpoint between every MCP (Model Context Protocol) client and every MCP server. Federation, auth, policy, caching, and audit — built on the official MCP Go SDK on both sides of the proxy.

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40/40official MCP conformance checks, run through the gateway on every merge ~0.2 mstypical added p50 latency (Apple Silicon, in-process upstream); CI gates every merge at < 5 ms 1 binarystatic Go binary or ~22 MB distroless container, no local state Apache-2.0open source, on GitHub

See it live.

demo.fold.run federates three public MCP servers behind one endpoint — the unmodified release binary, governed by its own config. Point any MCP client at it. Rate-limited, unauthenticated, no warranty; live status on /status. Copy-paste walkthrough: try the demo.

demo.fold.run/mcpthree upstreams · one endpoint

cfdocs__*

Cloudflare's public docs MCP server — a real third-party upstream, governed and namespaced like any internal one.

git__*

GitMCP — a public 2025-era server on the session handshake. Behind the gateway it is just another namespace.

jobs__*

A task-minting demo server. Start a job, then poll it with nothing but the task id — fold routes every poll to the owner.

Run it in 60 seconds.

fold is a single static binary with no local state. One config file in front of your first server, governance when you're ready.

Describe your upstreams

fold.config.json

{
  "upstreams": [
    {
      "id": "github-tools",
      "url": "https://mcp.platform.acme.com/mcp",
      "namespace": "gh",
      "owner": { "org": "acme-platform", "team": "devex" }
    }
  ]
}

Run it

shell

# one upstream, one governed endpoint — 60 seconds
$ go run github.com/fold-run/fold/cmd/fold@latest --config fold.config.json
# or the container:
$ docker run -p 8080:8080 -e FOLD_CONFIG="$(cat fold.config.json)" ghcr.io/fold-run/fold

Point a client at it
Any MCP client connects to /mcp and sees one virtual server named fold with every team's tools. MCP endpoint: http://localhost:8080/mcp · health: /healthz · metrics: /metrics

Binary

A single static Go binary — go install, or grab a prebuilt archive from GitHub releases. Linux and macOS, amd64 and arm64.go install github.com/fold-run/fold/cmd/fold@latest

Container

Multi-arch and distroless, ~22 MB. Config injected as a file or straight through FOLD_CONFIG.ghcr.io/fold-run/fold

Kubernetes

A Helm chart with probes, HPA, and ServiceMonitor — plus fold-discovery, so labeled Services join the federation on their own.

One gateway. A family of problems.

Most deployments start with one of these and grow into the others — they all ride the same config file.

Federate

Unify a federation

Acquisitions, child orgs, and teams each ship their own MCP servers — any language, any SDK. fold presents them as one virtual server with namespaced tools. No team rewrites anything.

Discover upstreams automatically

A team ships an MCP server, the registry lists it, and it appears behind the gateway — no config change. On Kubernetes, label a Service fold.run/upstream: "true" and fold-discovery does the rest.

Run tasks across the federation

Long-running work flows through fold: task polls and updates route to the server that owns the task — remembered at mint, or found by probe — and tasks/list merges every org, scoped per principal.

Govern

Draw the security boundary

One choke point for authentication, deny-by-default tool allowlists, per-principal visibility, and an audit event for every request — including the denials.

Broker credentials

Clients hold one token with fold as audience; fold exchanges it per upstream (RFC 8693) or injects service credentials. API keys never reach agents.

Govern vendor MCP servers

Put third-party and SaaS MCP endpoints behind your own auth, policy, and audit — instead of scattering per-user API keys across every client.

Operate

Protect fragile services

List caching, global and per-upstream rate limits, and circuit breakers stand between agent traffic storms and your internal systems.

Expose tools outward, carefully

Offer partners a curated, policy-scoped subset of internal tools on one hardened endpoint — a single static binary, self-hosted in your VPC.

Conformant, provably

The official MCP conformance suite runs through fold on every merge — 40/40 checks, including sampling, elicitation, and subscriptions bridged through the gateway.

Start where it hurts.

A single passthrough upstream in front of your most-used server is one config file away. Governance grows from there.

Get started