Run it locally

Five minutes, no signup: run fold on localhost in front of a real MCP server and watch federation, namespacing, and the health surfaces work. Everything here is the same binary and config you’d deploy to production.

One upstream, one container

Point fold at any streamable-HTTP MCP server you can reach — one of your own, or a public one:

cat > fold.config.json <<'EOF'
{
  "upstreams": [
    { "id": "docs", "url": "https://docs.mcp.cloudflare.com/mcp", "namespace": "docs" }
  ]
}
EOF

docker run --rm -p 8080:8080 \
  -e FOLD_CONFIG="$(cat fold.config.json)" \
  ghcr.io/fold-run/fold:latest --host 0.0.0.0

(Prefer Go? go run github.com/fold-run/fold/cmd/fold@latest --config fold.config.json does the same without Docker — see Getting started.)

Poke at it

# Health: per-upstream connectivity, latency, breaker state
curl -s http://localhost:8080/healthz | jq

# Prometheus metrics
curl -s http://localhost:8080/metrics | grep fold_requests_total

Then point any MCP client at http://localhost:8080/mcp. You’ll see one virtual server whose tools carry the docs__ prefix — fold merged the upstream’s list and namespaced it on the way through. Drop the namespace field (single upstream only) and fold runs passthrough: behavior through the gateway matches hitting the upstream directly.

docker compose, with room to grow

The repo ships a compose.yaml for the local/single-host shape — config mounted read-only, JSON logs, and an optional Redis profile for multi-instance state:

git clone https://github.com/fold-run/fold.git && cd fold
cp fold.config.example.json fold.config.json   # then trim it to taste
docker compose up
# several instances sharing state:
docker compose --profile redis up

The image is distroless — no shell inside — so check health from the host: curl -fsS http://localhost:8080/healthz.

Turn on governance

fold.config.example.json is a full federated example: two upstreams with different credential strategies (RFC 8693 token exchange and a static API key), required OAuth with an issuer allowlist, a deny-by-default policy, audit to stdout, and tracing. Validate any edit before running it:

go run github.com/fold-run/fold/cmd/fold@latest --validate --config fold.config.json

fold --schema prints the config’s JSON Schema for editor completion. When localhost looks right, the deployment guide takes the same config to Docker, Kubernetes, or a VM — and the configuration reference covers every block you just used.