After getting Claude Code running against a local Ollama instance, the next natural experiment was pointing it at DeepSeek’s API instead. The goal: keep the polished Claude Code interface and agentic loop, but swap out the model for something dramatically cheaper — without touching any Claude Code internals.

Spoiler: it works, and it takes four lines of batch script.

Why DeepSeek?

DeepSeek offers an Anthropic-compatible API endpoint at https://api.deepseek.com/anthropic. Because it speaks the same Messages API format that Claude Code expects, no proxy, adapter, or patching is needed. You just point the CLI at a different base URL and hand it a DeepSeek API key.

The cost difference is significant:

For long coding sessions with large codebases — the exact use case Claude Code is built for — that difference adds up fast.

The batch file

The entire setup fits in a single .bat file. Save it anywhere on your PATH and call it instead of claude:

:: claude-deepseek.bat
:: Launches Claude Code CLI pointed at DeepSeek's Anthropic-compatible API
@echo off
set ANTHROPIC_BASE_URL=https://api.deepseek.com/anthropic
set ANTHROPIC_AUTH_TOKEN=YOUR_DEEPSEEK_API_KEY
set ANTHROPIC_MODEL=deepseek-v3
set ANTHROPIC_DEFAULT_SONNET_MODEL=deepseek-v3
claude %*

The %* at the end passes any arguments through to Claude Code unchanged, so flags like --continue or --model still work as expected.

How it works

Claude Code reads three environment variables before making any API call:

Setting these four variables before invoking claude is all that is needed. The CLI never knows it is not talking to Anthropic.

Model naming

DeepSeek’s model names on their Anthropic-compatible endpoint follow their own convention. At time of writing:

deepseek-v3          # general-purpose, fast
deepseek-r1          # reasoning model, slower but stronger on complex tasks

Check DeepSeek’s documentation for the current list — model names can change between API versions.

Limitations to be aware of

This approach works well for routine coding tasks, but there are a few things to keep in mind:

• Context window — DeepSeek V3 supports up to 128k tokens, which is sufficient for most projects but smaller than Claude’s 200k limit.
• Tool use fidelity — Claude Code relies heavily on tool/function calling. DeepSeek is generally reliable here, but edge cases exist with complex nested tool calls.
• Model updates — DeepSeek updates their models more frequently than Anthropic. A model string that works today may behave differently after a silent update.
• Data privacy — Unlike the fully local Ollama setup, your code is still sent to an external API. Factor this in for sensitive or proprietary projects.

Getting a DeepSeek API key

Create an account at platform.deepseek.com, navigate to API keys, and generate a new key. Top up credit as needed — the rates are low enough that a small amount goes a long way for coding sessions.

That is genuinely all there is to it. Four environment variables, one .bat file, and Claude Code works exactly as you would expect — file editing, multi-step reasoning, shell commands — just billed at a fraction of the usual cost.

// tested on Windows 11 · Claude Code CLI 1.x · DeepSeek V4 via api.deepseek.com/anthropic