Synapse: an open-source TypeScript gateway unifying multiple MCP servers behind one login

Comfortable_Cat_6207 · reddit · 2026-09-16

Tired of configuring auth per MCP server in Claude Desktop and Cursor, the author built Synapse, an open-source TypeScript template (RohiRIK/synapse-mcp) that puts many MCP servers behind a single client connection and one authentication/tenant context.

Key design choices: the client connects once over stdio; the gateway discovers tools from all configured services in parallel with prefixed names (billingcreateinvoice, crmgetuser) so the model picks a tool but never a tenant; auth and X-Tenant-ID come from process env rather than arguments, nested tenantid args are rejected, and redirects/cross-origin endpoints are blocked so tokens can't follow a 302. If one backend is down the others keep working. Honest limits: tools only (no resources/prompts), SSE downstream by design, and the header alone isn't enough—each backend must still enforce tenancy. Bun for build/test, Node to run.

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