The software line
Open WebUI publishes no price list, and its own enterprise page answers the cost question directly: Open WebUI "is free to use as-is for everyone. You can deploy it today without an enterprise agreement." See Open WebUI's enterprise page. There is no per-seat software fee, and the core chat interface is free to run.
The same page covers the one paid path. Internal use with the original branding exactly intact is free, while white-labelling, rebranding or otherwise changing that branding calls for an enterprise agreement with the project.
Kortix publishes its numbers instead of quoting them. Free is $0 with 200 credits per month and 1 project, and the team plan is $40 per seat per month with 2,500 credits per month per seat, pooled (Kortix). Self-hosting Kortix costs no software fee at all.
The hosting line
A self-hosted Open WebUI install still needs a server, a database and object storage, and someone to run them. That is the real cost behind "free": a machine that stays up, a backup policy, and the time to operate it. Open WebUI's own architecture notes describe the shared databases, storage and Redis it needs so replicas stay interchangeable behind a load balancer (Open WebUI's enterprise page).
Kortix moves that line for teams that would rather not run a server. Kortix Cloud hosts the platform, a team can place it in its own VPC or on-prem network, and self-hosting runs as one Docker Compose stack on a Linux box you control (Read the docs). Self-host is free.
The model line
Both tools send work to a model provider, and that provider is the largest recurring cost in most deployments. Open WebUI points at Ollama or any OpenAI-compatible API, so the model spend is whatever those keys cost. Kortix accepts any model provider with your own keys, the ChatGPT plan you already pay for, or an OpenCode Console account, so a team can route model spend to a bill it already holds.
On Kortix, sandbox compute and optional managed model tokens draw from the same credit pool, and Agent Computer compute is billed per second and is $0 while stopped (Kortix). A self-hosted Kortix instance uses your own model key and your own compute.
Self-host or cloud
The choice between self-hosting and a cloud plan is operational, not a price tier. Self-hosting either tool keeps every byte on your infrastructure and puts the operating work on your team. A cloud plan removes the server and keeps the configuration in a repo you own. Kortix is open source, so the same platform runs both ways: start on Kortix Cloud, then move it to your own box, or begin self-hosted. Self-hosting Kortix covers the install in full.