Open WebUI vs Stack AI
Updated April 29, 2026
Overview
Open WebUI is the de-facto self-hosted AI chat platform — a feature-rich, extensible web UI that runs entirely offline and supports Ollama, OpenAI-compatible APIs, MCP servers, RAG with 9+ vector databases, voice I/O, and multi-user RBAC. 124K+ GitHub stars, 282M+ downloads.
Stack AI is a no-code platform for building AI workflows and applications. It provides a visual drag-and-drop interface for creating RAG pipelines, chatbots, document processing workflows, and AI agents. Stack AI connects to enterprise data sources and deploys as APIs or embeddable widgets.
Key features
Core capabilities each platform advertises.
- Self-hosted ChatGPT-style UI for Ollama + OpenAI-compatible APIs
- RAG with 9+ vector databases (Chroma, Qdrant, Milvus, Weaviate)
- 15+ web search providers, voice I/O, MCP server integration
- Multi-user RBAC, LDAP/SSO, audit-friendly architecture
- Image generation via DALL-E, Gemini, ComfyUI, AUTOMATIC1111
Strengths and tradeoffs
What each tool does well, and the limitations to keep in mind.
Pros
- Most-deployed self-hosted ChatGPT clone — 282M+ downloads
- Genuinely enterprise-grade: RBAC, SSO, multi-user from day one
- Massive feature set, all in one Docker container
- MIT license — fully free and modifiable
- Pairs perfectly with Ollama for local-only AI
Cons
- Self-hosting requires infrastructure expertise
- Heavy feature surface can overwhelm casual users
- Less polished than commercial UIs like ChatGPT
- Performance depends on chosen LLM backend
Pros
- Production-ready
- Good performance
- Active development
Cons
- Pricing varies
- Setup required
What people are saying
Adds everything Ollama's CLI lacks — conversation history, file uploads for document chat, web search, multi-user accounts, voice I/O, and a lot more.
Read full reviewOpen WebUI or Stack AI — which should you choose?
Choose Open WebUI if you wantChoose if you want
- Self-hosted private ChatGPT replacement for enterprises
- On-prem RAG with internal documents
- Multi-user team-level AI deployments with permissions
- Air-gapped AI environments (regulated industries)
- Local AI workflows powered by Ollama
Choose Stack AI if you wantChoose if you want
Compare Open WebUI and Stack AI on your own traffic
Respan lets you trace LLM and agent calls across any model or framework, A/B test prompts on production traffic, and route requests across 500+ models through one gateway.