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API reference style guide

Codex CLI API relay: endpoint, headers, and smoke-test workflow

If you need Codex CLI API relay support for a third-party API environment, the main job is simple: point the client to an OpenAI-compatible relay, keep the request format clean, and verify that the model call, authentication, and response shape all match expectations.

Open the relay homepage Review OpenAI-compatible relay details
Codex base_url API中转站 Codex API接入 Third-party API

Endpoint

What to configure

For Codex CLI API relay usage, the most important field is the base URL. Use an OpenAI-compatible relay endpoint so the CLI can send chat or completions requests without changing the client logic.

In practice, this means you are not rewriting the toolchain. You are only swapping the upstream destination to a compatible API中转站.

Criteria to check first

  • Supports OpenAI-style paths and JSON payloads
  • Accepts standard Bearer authorization headers
  • Returns predictable 4xx/5xx errors for bad input
  • Works with Codex base_url configuration

Headers

For Codex API接入, keep headers minimal and explicit. Most issues come from mismatched keys, copied whitespace, or an incorrect environment variable. A clean setup usually looks like this: 

Authorization: Bearer YOUR_API_KEY
Content-Type: application/json

Some teams add organization or project headers, but the relay should work first with only the essentials. After that, you can test optional headers one by one.

Example

A practical smoke test is more useful than a long theory checklist. Start by exporting the base URL, confirm the CLI reads it, then send a tiny prompt. If the relay is working, you should receive a structured response instead of a transport error. 

export OPENAI_BASE_URL=https://59api.com/v1
export OPENAI_API_KEY=YOUR_API_KEY

codex --model gpt-4.1-mini "Say hello in one sentence."

Smoke-test steps

  • Set OPENAI_BASE_URL=#/v1 and reload the shell.
  • Verify the CLI picks up the new Codex base_url value.
  • Run a one-line prompt to confirm auth and routing.
  • Check latency, response format, and any rate-limit messaging.
  • Retry with a different model only after the first request succeeds.

FAQ

Why use a relay instead of direct API access?

A relay can simplify network routing, centralize keys, and help teams standardize access for multiple tools that expect an OpenAI-compatible endpoint.

What if the CLI returns a 401 or 403?

Recheck the token format, confirm the environment variable is loaded, and make sure the request is reaching the correct third-party API endpoint.

Does the relay require client code changes?

Usually no. If the endpoint is compatible, Codex CLI API relay setup is mainly a base URL and header configuration task.

Manual CTA

If you want to compare routing behavior, request shape, or documentation style, visit the relay directly and inspect the OpenAI-compatible relay entry points yourself.

Visit # Check relay access