What it is
DeepSeek is not a separate harness: its API accepts the Anthropic format at https://api.deepseek.com/anthropic, so Claude Code can run on DeepSeek models by changing environment variables. Its docs map claude-opus model names to deepseek-v4-pro and claude-sonnet and claude-haiku names to deepseek-flash.
Install
Install Claude Code first
$ npm install -g @anthropic-ai/claude-code
Linux, macOS
$ export ANTHROPIC_BASE_URL=https://api.deepseek.com/anthropic
$ export ANTHROPIC_AUTH_TOKEN=<your DeepSeek API key>
$ export ANTHROPIC_MODEL=deepseek-flash[1m]
Start
$ cd your-project
$ claude
The key comes from the API keys page of the DeepSeek Platform.
Commands are copied from the source on the checked date. Installers change; if one fails, the source link has the current version.
Walk through it step by step in LearnTry it in the playground