supergateway

Supergateway bridges MCP servers that run over stdio to network transports (SSE, WebSockets, or Streamable HTTP) and can also proxy remote SSE/Streamable HTTP MCP servers back to a local stdio interface.

Evaluated Mar 30, 2026 (22d ago)
Repo ↗ API Gateway mcp gateway stdio sse websockets streamable-http json-rpc
⚙ Agent Friendliness
55
/ 100
Can an agent use this?
🔒 Security
52
/ 100
Is it safe for agents?
⚡ Reliability
35
/ 100
Does it work consistently?

Score Breakdown

⚙ Agent Friendliness

MCP Quality
75
Documentation
80
Error Messages
0
Auth Simplicity
80
Rate Limits
0

🔒 Security

TLS Enforcement
60
Auth Strength
50
Scope Granularity
20
Dep. Hygiene
65
Secret Handling
70

TLS is not explicitly required for all inbound modes; outbound/upstream URLs are shown as https in examples, but no security policy is documented. Auth support is header-based (Bearer token/custom headers) without mention of scoped/role-based controls. CORS can be enabled broadly (allow all origins when --cors has no values), which can increase exposure if deployed beyond localhost.

⚡ Reliability

Uptime/SLA
0
Version Stability
65
Breaking Changes
35
Error Recovery
40
AF Security Reliability

Best When

You need to convert MCP transport style (stdio <-> SSE/WS/Streamable HTTP) with a lightweight command-line/server runtime.

Avoid When

You need strict operational guarantees around retries/idempotency semantics and clear published error codes for all failure modes.

Use Cases

  • Expose an MCP stdio server as an SSE server for web/remote clients
  • Connect to a remote MCP server over SSE or Streamable HTTP and make it usable from local CLI/MCP tooling via stdio
  • Provide WebSocket access to MCP stdio servers
  • Debug or integrate MCP servers that only support stdio in environments that expect network transports
  • Run MCP servers behind a public tunnel (e.g., ngrok) for remote access

Not For

  • Use as a general-purpose API gateway for arbitrary HTTP APIs (it is MCP-transport focused)
  • Handling production-grade multi-tenant auth/authorization unless additional access controls are added around its endpoints
  • Cases where you require published, machine-readable API specs (no OpenAPI/SDK is described)

Interface

REST API
Yes
GraphQL
No
gRPC
No
MCP Server
Yes
SDK
No
Webhooks
No

Authentication

Methods: Static Authorization header via --oauth2Bearer (Bearer token) Custom headers via --header (e.g., X-*)
OAuth: No Scopes: No

The README describes adding headers when connecting to upstream SSE/Streamable HTTP MCP servers (and enabling CORS for incoming clients). It does not describe OAuth flows, per-route authorization, or fine-grained scopes for Supergateway itself.

Pricing

Free tier: No
Requires CC: No

No pricing information for the package itself. The README mentions hosted services (Supermachine/Superinterface/Supercorp) but does not specify their pricing.

Agent Metadata

Pagination
none
Idempotent
False
Retry Guidance
Not documented

Known Gotchas

  • Supergateway is a transport bridge, not a standard CRUD API; client code must speak MCP-over-chosen-transport (JSON-RPC style).
  • Authentication is implemented by injecting headers to upstream requests (and enabling CORS). No guidance is provided on retry behavior or how failures map to specific MCP error codes.
  • Some client tools may have CLI argument limitations (README mentions Cursor bug with spaces in Authorization; use --oauth2Bearer instead of --header for Bearer tokens).

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Scores are editorial opinions as of 2026-03-30.

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