Codex CLI

Codex CLI runs on OhMyGPT with one provider entry in its config file. Your OhMyGPT key then gives Codex the GPT models and the rest of the catalog, switchable per run with codex -m. You can test the whole setup for free with ohmygpt/mock.

ConfigureCopy Anchor Link

Add the provider to ~/.codex/config.toml:

model = "openai/gpt-5.5"
model_provider = "ohmygpt"

[model_providers.ohmygpt]
name = "OhMyGPT"
base_url = "https://api.ohmygpt.com/v1"
env_key = "OHMYGPT_API_KEY"
wire_api = "responses"

Codex reads your key from the variable named in env_key. Export it in the shell that runs Codex:

export OHMYGPT_API_KEY="sk-..."
codex

• base_url ends in /v1. Codex appends /responses.
• wire_api = "responses" selects the Responses API, which Codex uses for every provider.
• model is any model ID from Choose a model. To use another model for one run, start Codex with codex -m <model id>.

Check the connectionCopy Anchor Link

Send a Responses request, the kind Codex sends, to the free test model ohmygpt/mock:

curl https://api.ohmygpt.com/v1/responses \
  -H "Authorization: Bearer $OHMYGPT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "ohmygpt/mock", "input": "ping"}'

{
  "id": "resp_MRazQMjAopUMBIjoOfs2bSUL",
  "object": "response",
  "status": "completed",
  "model": "mock",
  "output": [
    {
      "type": "message",
      "id": "msg_0",
      "role": "assistant",
      "status": "completed",
      "content": [
        {
          "type": "output_text",
          "text": "This is a mock reply from OhMyGPT. Your integration works; switch to a real model when ready."
        }
      ]
    }
  ],
  "usage": { "input_tokens": 15, "output_tokens": 17, "total_tokens": 32 }
}

To run Codex itself at no cost, start it with codex -m ohmygpt/mock. The mock calls the first tool Codex declares, gets the result back and replies with text, so you see one full turn of the agent loop. The mock is available once your account has been topped up.

Choose a modelCopy Anchor Link

List the models you can use with Codex:

curl -s https://api.ohmygpt.com/v1/models \
  | jq -r '.data[] | select(.available and any(.protocols[]?; .id == "openai-responses")) | .id'

Prices for each are on the Models page.

Codex is tuned for OpenAI's GPT models, and openai/gpt-* IDs give you the full experience. Other models in the list, such as zhipu/glm-5.3, run Codex too, including its tool calls and reasoning settings.

TroubleshootingCopy Anchor Link

Every response carries an X-Request-ID header, and Usage shows what each request cost.