A new open source tool called claude-code-proxy lets developers use Anthropic's Claude Code CLI with their ChatGPT Plus/Pro subscription or Kimi Code account instead of paying for Anthropic API access. Posted to Hacker News by developer raine, the project addresses what many in the community see as Anthropic increasingly tightening usage limits while competitors like OpenAI offer more generous quotas.

Why This Matters

The author notes that Claude Code remains 'the best harness around' despite occasional frustrations with updates—but Anthropic's rate limiting has become a pain point. Rather than accepting OpenCode or Codex as alternatives (which the developer describes as having rough UX, especially around skills), raine built a translation proxy that routes Claude Code traffic through existing subscriptions. This means developers can leverage their already-paid ChatGPT Plus/Pro accounts for AI-assisted coding without abandoning Claude Code's interface and workflows.

Technical Implementation

The proxy runs locally on 127.0.0.1:18765 by default, translating Anthropic API requests into provider-specific formats. For Codex (ChatGPT), it hits the chatgpt.com/backend-api/codex/responses endpoint using OAuth authentication against auth.openai.com. For Kimi, it calls api.kimi.com/coding/v1/chat/completions with device-code OAuth via auth.kimi.com. The translation layer handles system blocks, tool definitions, and response streaming between formats—though some features don't carry over perfectly (more on that below).

Supported Models

Codex works with gpt-5.4, gpt-5.3-codex, gpt-5.3-codex-spark, gpt-5.2, and gpt-5.4-mini confirmed on Plus tier accounts. Kimi exposes a single wire model (kimi-for-coding, aliased as kimi-k2.6 or k2.6) with 256K context, reasoning support, and image/video input capabilities. Model selection happens via the ANTHROPIC_MODEL environment variable—prefixes like gpt-5.4 route to Codex while kimi-for-coding routes to Kimi. The proxy rejects unknown models with a 400 error listing supported IDs.

Installation Options

The tool installs via Homebrew on macOS/Linux, an automated install script, or manual binary downloads for Windows (both amd64 and arm64 builds). After installation, users authenticate with their chosen provider using browser OAuth (PKCE flow) or device-code flow for headless machines. Credentials store in Keychain on macOS or encrypted files elsewhere. Starting the proxy is a single command: claude-code-proxy serve.

Known Limitations

The project doesn't shy away from caveats. Terms of service compliance is described as 'a gray area'—using Codex or Kimi backends from non-official clients carries risk. Rate limits are shared across all clients on your upstream account. More concretely, image inputs in tool results get replaced with placeholders for Codex since the Responses API only accepts strings there (Kimi passes them through). Reasoning blocks aren't forwarded to Claude Code when using Codex but are rendered as thinking content with Kimi.

Toggling Between Providers

For developers who maintain Anthropic access alongside proxy routing, raine includes a wrapper script pattern that injects proxy environment variables only when a flag file exists. A toggle script flips the flag on/off, letting you switch between direct Anthropic traffic and Codex/Kimi without modifying Claude Code's settings.json. This keeps your config portable across machines.

Key Takeaways

  • Bypass Anthropic's usage caps using existing ChatGPT Plus/Pro or Kimi subscriptions
  • Single proxy handles multiple providers with model-based routing
  • Reasoning effort settings translate between platforms (Claude to Codex/Kimi formats)
  • Credentials stored securely in platform keychains or encrypted local files
  • Terms of service gray area—use responsibly and understand the risks

The Bottom Line

This is exactly the kind of creative infrastructure hacking that keeps AI tooling interesting. Whether Anthropic's TOS team will come knocking remains to be seen, but for developers already paying for generous ChatGPT plans, this proxy unlocks Claude Code's superior CLI experience without the subscription overhead. Worth bookmarking—assuming it doesn't get shut down first.