{
  "$type": "site.standard.document",
  "bskyPostRef": {
    "cid": "bafyreigolndlttyjyeeowmgpnbryq45evliu7y6cvsjhfsxxngx4w74krm",
    "uri": "at://did:plc:pgryn3ephfd2xgft23qokfzt/app.bsky.feed.post/3mhhl4qosys72"
  },
  "path": "/t/a-comprehensive-look-at-gpt-5-4-mini-and-nano-openai-s-small-models-with-big-ambitions/174372#post_4",
  "publishedAt": "2026-03-20T00:40:39.000Z",
  "site": "https://discuss.huggingface.co",
  "tags": [
    "OpenAI Developers"
  ],
  "textContent": "Oh. I see “Codex” in the menu, but I’ve never used it…\nOh, I see:\n\n* * *\n\n**Codex = best for a human developer. API = best for software and automation.**\n\n## Use Codex when\n\nYou are **personally coding** in a repo and want help with writing, editing, reviewing, debugging, and running code. OpenAI describes Codex as a coding agent that can **read, edit, and run code** , and says you can use it in the **CLI, IDE, web, mobile, and CI/CD pipelines**. ChatGPT **Plus, Pro, Business, Edu, and Enterprise** plans include Codex. (OpenAI Developers)\n\n## Use the API when\n\nYou need your **app or backend** to call models directly. OpenAI’s code generation guide says to use OpenAI models in your application, and for most API-based code generation to start with **`gpt-5.4`**. The API is the right fit when the model is part of a product, service, background job, or larger workflow rather than an interactive coding session. (OpenAI Developers)\n\n## Practical difference\n\n  * **Codex** : “help me work on this codebase.”\n  * **API** : “let my software use a model.” (OpenAI Developers)\n\n\n\n## My rule of thumb\n\nIf you are a solo dev in VS Code, Cursor, Windsurf, JetBrains, or the terminal, **start with Codex**. OpenAI now supports Codex in the IDE and explicitly supports those coding environments. (OpenAI Developers)\n\nIf you are building:\n\n  * a product for users\n  * automation or batch jobs\n  * a service that needs direct model calls\n  * custom orchestration around prompts, tools, or outputs\n\n\n\nthen use the **API**. OpenAI also continues to release Codex-optimized models into the Responses API, which shows the API remains the integration path for programmable systems. (OpenAI Developers)\n\n## Bottom line\n\nFor **coding yourself** : **Codex**.\nFor **building software that uses AI** : **API**. (OpenAI Developers)\n\nA compact version is:\n\n**Codex is a tool. API is infrastructure.**",
  "title": "A Comprehensive Look at GPT-5.4 Mini and Nano: OpenAI’s ‘Small’ Models with ‘Big’ Ambitions"
}