Point your tools at it · curl

curl against the plan you already pay for

Two base URLs, one key. Anthropic-shaped clients talk to http://localhost:3456; OpenAI-shaped clients — chat/completions and, since 6.3, the Responses API — talk to http://localhost:3456/v1. The key is dario (any value works until you set DARIO_API_KEY, which then has to match).

Setup

curl

curl http://localhost:3456/v1/messages -H "content-type: application/json" \
  -d '{"model":"claude-sonnet-5","max_tokens":256,"messages":[{"role":"user","content":"Hello!"}]}'

curl http://localhost:3456/v1/chat/completions -H "content-type: application/json" \
  -d '{"model":"gpt-5.5","messages":[{"role":"user","content":"Hello!"}]}'

Before that

Install dario, log in, leave it running

Three commands, once. The proxy binds 127.0.0.1:3456 and holds your login; every tool on the machine shares it. Add a ChatGPT plan with dario add altman and the two fail over to each other.

terminal

$ npm install -g @askalf/dario
$ dario login        # your Claude plan: Pro, Max 5x or Max 20x
  Login successful.
$ dario proxy        # leave it running
  dario · http://localhost:3456
  Your Claude subscription is now an API.

0 runtime dependencies SLSA-attested every release Nothing phones home MIT, independent, unofficial

Other tools

Same URL, same key

Codex CLI Claude Code Cursor Cline · Roo Code · Kilo Code Aider Continue.dev Zed OpenHands OpenClaw Codex CLI · OpenAI SDK · any OpenAI-compatible tool Claude Agent SDK · Anthropic SDK Docker Compatibility matrix

Something not listed? If it reads ANTHROPIC_BASE_URL or OPENAI_BASE_URL, or has a "Base URL" field, it works. The compatibility matrix says which tools are exercised end-to-end, which are inferred from a shared code path, and which are untested — one honest cell per tool.