Where a model runner stops and a chat UI starts
Ollama and Open WebUI sit at two different layers, and they are compared because they are installed together. Ollama is a model runner: it serves open models on your own computer or in Ollama's cloud, and it exposes a local REST API that other programs call (Ollama's download page). Open WebUI is a self-hosted chat front end: it connects to Ollama and to any OpenAI-compatible API, and puts a multi-user chat window, document retrieval, web search and plugins over them (Open WebUI's docs). One runs the model; the other is where a person types.
Ollama's repository lists Open WebUI among the interfaces built on top of it, which is the clearest sign that one is built on the other. If a script needs a model endpoint, Ollama alone is enough. If a team needs a shared window with accounts and history, Open WebUI is the layer that adds it.
What each layer gives a team
Ollama runs open models in two ways, from its download page: locally on the computer, where speed depends on the hardware, or in Ollama's cloud, where models run on its servers and need no download. It also ships a REST API and Python and JavaScript clients, so an application can call a model with no chat UI involved at all. Ollama's homepage reports 9M+ installs a month and 1B+ model downloads (checked October 2026).
Open WebUI's docs describe it as a self-hosted platform built to run entirely offline, with support for Ollama and OpenAI-compatible APIs. It adds a provider-agnostic interface, per-user accounts, retrieval over your own files, and a plugin and tool system. Recent work moved it toward execution: Open Terminal gives an agent a terminal and filesystem inside the chat, and Terminals gives each user an isolated environment on a team deployment.
Where a team outgrows both
Both tools center the interface. A person drives each turn, and the output is an answer or an artifact inside the conversation. When the work has to change a real system, two questions decide the tool: which machine runs it, and who approves the result.
Kortix answers both. Your agents, skills, company memory and every connector live in one git repo you own. Each session runs on its own cloud computer and its own branch, an agent takes real actions in your tools, and the work reaches main through a change request a person reads first (Kortix docs). That is the layer neither Ollama nor Open WebUI fills, because a model runner and a chat UI have no change-request step.
Choosing between them
Pick Ollama alone when a script or an app needs a model endpoint, local or in Ollama's cloud, with no team interface. Pick Open WebUI when a team wants a self-hosted chat and document window over local and API models, with plugins and accounts. Pick Kortix when the output has to be finished work: agents that use your tools, return deliverables you keep, and land each change for review on the infrastructure you choose.
Ollama and Open WebUI stay useful beside it. Kortix works with any model provider with your own keys, so a team can keep the runner it already has. What changes is where the work lands: agents, memory and connectors in one repo the team owns.