Open WebUI

Open WebUI started as a simple interface for Ollama but has grown into a full-featured ChatGPT alternative that rivals commercial offerings. The self-hosted approach means your conversation history, uploaded documents, and custom prompts never touch third-party servers.

The interface is polished and responsive—dark mode, code highlighting, LaTeX rendering, and markdown support all work flawlessly. Upload a PDF and ask questions about it; the RAG integration surfaces relevant passages with citations. Voice input and text-to-speech are built in, not bolted on.

Where Open WebUI shines is customization. The system prompt library lets you create specialized assistants—a coding mentor, a legal document reviewer, a creative writing coach. Pipelines extend functionality: filter outgoing prompts, modify responses, integrate external APIs. The community has built pipelines for everything from content moderation to automatic translation.

Multi-user support with granular permissions makes this suitable for teams. Set up shared model access, restrict certain features to admins, configure rate limits. LDAP and OAuth integration means it fits into existing corporate identity systems.

Hardware requirements scale with use. A single user on a modest laptop runs fine; a team of twenty needs proper server infrastructure. The documentation covers deployment scenarios from Raspberry Pi to Kubernetes clusters.

Best fit: Privacy-conscious individuals, teams wanting ChatGPT functionality without data sharing, organizations needing on-premises AI.