n8n

Workflow automation platform (~199k stars) often shorthanded as self-hosted Zapier, but the license is the Sustainable Use License (fair-code, source-available), NOT OSI open source: you can self-host the Community Edition free for internal use, enterprise features (.ee files) sit under a separate n8n Enterprise License, and offering n8n itself as a service to third parties is restricted. Since late 2025 it speaks MCP in both directions, and the two nodes are not the same risk profile. The MCP Server Trigger (n8n-nodes-langchain.mcptrigger) makes n8n an MCP server: every tool node you wire into it (HTTP Request, Postgres, Slack) shows up in an agent's tool list and the agent executes it with n8n's STORED credentials, not its own, so a prompt injection becomes a confused-deputy problem and the trigger's single bearer token gates the whole endpoint rather than individual tools. The MCP Client Tool (n8n-nodes-langchain.toolmcp) is the lower-stakes outbound direction. Honest catch: the July 29 2026 release added an AI workflow builder and admin-managed credentials, NOT MCP (which predates it); and community MCP nodes like czlonkowski/n8n-mcp run third-party code inside your instance with your instance's access.