Ollama vs Open WebUI

Ollama

An OpenAPI 3.1 file for the 15 native operations and llms.txt with 68 links to Markdown pages. No credential on the local API, and any caller that reaches it can pull, push, create and delete models.

Open WebUI

Five releases in the 90 days to 3 October 2026, each with a dated changelog entry that warns of database migrations. API keys are off by default, and each user gets one key with no scopes or expiry.

Ollama

1. Send "stream": false for one JSON body. The native routes stream NDJSON by default
2. Set OLLAMA_CONTEXT_LENGTH=64000 or options.num_ctx before agent work. The default is 4k below 24 GiB of VRAM
3. Back off on a 503. It means the queue (512 by default) is full
4. Put an authenticating proxy in front before binding past 127.0.0.1. The server checks no credential
5. Expect model names with a cloud tag to run on Ollama's servers. They need ollama signin and fail with OLLAMA_NO_CLOUD=1

Open WebUI

1. Ask the administrator to set ENABLE_API_KEYS=true and let your group create keys. sk- keys are refused until then
2. Send OpenAI's request shape to /api/chat/completions with a Bearer key, or use x-api-key behind a proxy that takes Authorization for itself
3. Call /api/models first and use an id from it. Model IDs depend on the instance's connections
4. Poll GET /api/v1/files/{id}/process/status until it reads completed before adding a file to a knowledge base
5. Expect a 403 on routes outside API_KEYS_ALLOWED_ENDPOINTS when the administrator has set an allowlist