Guide · Open source

How to use deepseek-harness: run the Web UI and build plugins

Updated 2026-10-29 · written with AI from the project's own documentation and checked against our catalogue data

DeepSeek Harness (dsh) is an open-source agent harness from DeepSeek AI, built so that nearly every part is a plugin. It runs on Cordis, a plugin framework, and can be started as a local Web UI. This guide covers how to start it, how to run it from a repository checkout, and what to know about its developer-preview status before you rely on it.

DeepSeek Harnessdeepseek-ai/deepseek-harness · ★ 269k · MIT Install options & downloads

Quick start

1Read the safety notice. Open SAFETY.md and review it before running the project, as the README asks.
2Install Node.js. Install Node.js, which the README lists as the prerequisite for running from npm.
3Start the Web UI. Run npx @deepseek-ai/dsh web to launch the local Web UI at http://127.0.0.1:3080.
4Clone for source work. If you want to work from source, clone the deepseek-harness repository from GitHub.
5Install and build. Run pnpm install, then pnpm run build to prepare the repository artifacts.
6Run the built app. Run pnpm dsh web to start the Web UI using the built artifacts.

What deepseek-harness is and who it suits

DeepSeek Harness is built on an everything-is-a-plugin architecture and powered by Cordis. The project is MIT licensed and written in TypeScript.

It suits developers who want to experiment with an agent harness they can extend with plugins, people already interested in the Cordis plugin model, and plugin authors who want to publish to the dsh-plugin topic. It is not a finished consumer app and is not intended for production systems yet.

Good fit: developers comfortable running a local dev tool from the command line
Not a fit: users who need a stable production system, since the README warns of compatibility-breaking changes
Not a fit: non-technical users looking for a finished consumer app

Read the developer-preview and safety notices first

The README states that DeepSeek Harness is in developer preview and iterating rapidly, and that there will be compatibility-breaking changes. Interfaces and APIs may change.

The README asks you to review the safety notice (SAFETY.md) before running the project.

Run the Web UI with npx

The quickest route is to install Node.js and run the package from npm. The command starts the Web UI at http://127.0.0.1:3080 by default and opens it in your default browser for a local launch.

Pass --no-open to run the server without opening a browser. An SSH launch only prints the host URL, because your SSH client or editor owns the local forwarded address. The README points to the Web UI guide at docs/user/guide/index.md for more.

npx @deepseek-ai/dsh web

Run from source with pnpm

To work from a repository checkout, you need Node.js and pnpm. Clone the repository, install dependencies, and build the artifacts before starting the Web UI.

The README notes that pnpm run build prepares the repository artifacts, and that pnpm dsh web uses those built artifacts without rebuilding. For active development, the README mentions pnpm run dev:web, which builds, serves, and rebuilds client bundles on source edits.

Install Node.js and pnpm
Clone the repository
Install dependencies and build artifacts
Start the Web UI

git clone https://github.com/deepseek-ai/deepseek-harness.git
cd deepseek-harness
pnpm install
pnpm run build
pnpm dsh web

Get help, contribute and write plugins

Send feedback or bug reports through GitHub Discussions. To make your plugin easier to find, add the dsh-plugin topic to its repository. The README also links a Discord community.

Start contributor work with CONTRIBUTING.md, then read the development guide (docs/development.md) and architecture documentation (docs/architecture.md). The README also says agents should follow AGENTS.md.

Bug reports and feedback: GitHub Discussions
Plugin discovery: add the dsh-plugin topic
Architecture: docs/architecture.md

What people use it for

Experimenting with an agent harness you can extend with plugins
Exploring the Cordis plugin model in a working project
Building and publishing a plugin tagged with the dsh-plugin topic
Running a local Web UI from the command line for development work

Frequently asked questions

How do I install deepseek-harness?

The README gives two routes. Install Node.js and run npx @deepseek-ai/dsh web to start the Web UI, or clone the repository, run pnpm install and pnpm run build, then run pnpm dsh web.

What are the requirements for deepseek-harness?

The README lists Node.js as the requirement for running from npm, and Node.js plus pnpm for running from source. It also assumes you are comfortable with the command line.

Is deepseek-harness free to use?

The project is released under the MIT licence, as stated in the README. Third-party dependency licences are listed in THIRD_PARTY_NOTICES.md.

Is deepseek-harness ready for production?

The README says it is in developer preview and that compatibility-breaking changes will happen. It is best suited to experimentation rather than stable production use.

What are alternatives to deepseek-harness?

Comparable projects named in the analysis are Cordis, LangChain, AutoGen and CrewAI. Cordis is the plugin framework dsh is built on, so it is the closest match if you want the same model.

Where does the Web UI run and how do I stop it opening a browser?

By default the Web UI runs at http://127.0.0.1:3080 and opens in your browser for a local launch. Pass --no-open to run the server without opening a browser.

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Our verdict

DeepSeek Harness suits developers who want to experiment with a plugin-based agent harness and who are comfortable with Node.js and the command line. It is a poor choice if you need a stable production system or a finished consumer app, given the developer-preview warnings about breaking changes.

Install options & downloads