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DeepSeek V4
DeepSeek V4
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Terminal coding agentOpenAI Chat CompletionsExperimental

Use DeepSeek V4 with DeepSeek Harness

Run the DeepSeek Harness developer preview with DeepSeek-V4.io as a custom OpenAI-compatible provider.

Create API KeyRead API Docs

DeepSeek-V4.io is an independent API gateway, not the official DeepSeek website. A paid DeepSeek-V4.io key is required.

How the integration works

DeepSeek Harness is DeepSeek's open-source, plugin-oriented agent harness. Its Web UI accepts a custom provider with a base URL, protocol, credential, and model catalog, so the DeepSeek-V4.io gateway can be configured without exposing upstream provider credentials. The harness is still a developer preview and may make compatibility-breaking changes.

One site key

Create and manage it on /developer.

OpenAI Chat Completions

The client talks to its native compatible endpoint.

Upstream hidden

Provider credentials and routing stay on the server.

Before you start

  • Node.js installed
  • A paid DeepSeek-V4.io account with an API key from /developer
  • A local project directory you are willing to expose to an agent with file and shell tools

Configure DeepSeek Harness

1.Start the official Web UI from your project directory

The current preview serves its local Web UI at http://127.0.0.1:3080 by default.

cd /path/to/your/project
npx @deepseek-ai/dsh web
2.Add DeepSeek-V4.io under Settings → Models

Provider IDs are permanent in saved sessions. Use a lowercase stable ID and keep the model text-only. Harness stores the key as a write-only credential reference, and saved model changes apply on the next request without a restart.

Provider type: Custom provider
Provider ID: deepseek-v4-io
Display name: DeepSeek-V4.io
Base URL: https://deepseek-v4.io/api/v1
API protocol: OpenAI Completions
API key: your-deepseek-v4-io-key
Model ID: deepseek-v4-flash

Verify the setup

The page remains Experimental until these checks pass against the public DeepSeek-V4.io gateway.

  1. 1Use Fetch available models and confirm deepseek-v4-flash is returned, or enter it manually.
  2. 2Choose a workspace and ask the agent to summarize one file without editing it.
  3. 3Run one read-only shell or file tool call and confirm the final response and Developer usage row both complete.

Troubleshooting

The Web UI or settings moved

DeepSeek labels Harness a developer preview and warns about compatibility-breaking changes. Recheck the official README and model-provider guide before treating this page as stable.

Fetching models returns 401

Use a paid DeepSeek-V4.io key created in /developer. A DeepSeek Platform or OpenRouter key is not valid for this gateway.

The model is missing after save

Confirm the base URL ends in /api/v1, set the protocol to OpenAI Completions, and add deepseek-v4-flash manually if model discovery is unavailable.

Sources and support boundary

Configuration fields are checked against the tool publisher's documentation. DeepSeek-V4.io owns this gateway guide and support for its endpoint; it does not represent the tool publisher.

Official DeepSeek Harness model-provider guide

Ready to connect DeepSeek Harness?

Create a DeepSeek-V4.io API key, copy the configuration above, and verify one read-only tool call before using it on a real project.

Open Developer Dashboard