Stack map: n8n, Open WebUI, and models

• Understand the role of n8n, Open WebUI, Ollama, vLLM, and a custom API.
• Separate chat, automation, model, and data so you can maintain the system.
• Design a first version that is cheap, private, and scalable.

usuarios
  -> Open WebUI: chat interno, modelos, herramientas
  -> n8n: workflows, webhooks, aprobaciones, integraciones
  -> API interna: reglas de negocio y permisos
  -> modelo:
       local: Ollama / llama.cpp
       produccion GPU: vLLM
       cloud puntual: proveedor externo
  -> datos:
       Postgres / Qdrant / ficheros
  -> operacion:
       logs, backups, alertas, limites

Decision rule

• Open WebUI: private interface for users, models, tools, and knowledge.
• n8n: visible automations, webhooks, connectors, approvals, and business logs.
• Ollama: simple local entry point for models on modest CPU/GPU.
• vLLM: model serving with GPU and higher concurrency.
• Custom API: permissions, sensitive rules, and operations you don't want left in an editable workflow.