Use the built-in web UI

The built-in web UI is mounted at /ui by default whenever you run mistralrs serve. Use cases:

• Sanity-checking a newly loaded model.
• Demonstrating tool calling and code execution without explaining the response envelope.
• Giving non-technical teammates a way to try a model behind an HTTP endpoint.

The UI is a single-page app bundled into the binary. Nothing is fetched from the network at runtime.

Basic usage

mistralrs serve -m Qwen/Qwen3-4B

Open http://localhost:1234/ui. The UI provides:

• A chat panel with markdown rendering, code block syntax highlighting, and streamed output.
• A settings drawer with sampling controls (temperature, top-p, top-k, max tokens) and a system prompt field.
• Inline rendering of thinking tokens when the model emits them.
• Tool-call visualization when --enable-search or --enable-code-execution is also set.
• Tool approval cards when approval mode is ask.
• Multimodal attachments when the loaded model supports images, audio, or video.

With agents enabled

mistralrs serve --agent -m Qwen/Qwen3-4B

(--agent is a shorthand for --enable-search --enable-code-execution. To turn the pieces on individually, use the two flags directly.)

When the model calls a tool, the UI renders a collapsed block in the conversation. Expanding shows the tool arguments and result. Search blocks display queries and retrieved URLs; code-execution blocks display the executed Python and any output or images.

The settings drawer controls search, code execution, and tool approval per conversation without restarting the server. Set Tool approval to ask to approve or deny each agent action inline.

On Linux and macOS, code execution uses the default OS-level sandbox unless the server is started with --sandbox off. For the server, HTTP, Python, Rust, and sandbox settings, see enable code execution.

With multimodal models

When the loaded model accepts images, a paperclip icon appears in the input bar. Attaching an image adds a {"type": "image"} content part. Audio and video work the same on supporting models.

Modality support per model is in the supported models reference.

System prompt and sampling

The settings drawer state is persistent per browser. System prompts and sampling parameters survive reloads.

Clearing browser local storage for the site resets all UI state.

Disabling the UI

Pass --no-ui to mistralrs serve to skip mounting the UI router. The HTTP API continues to serve normally.