Which model on the api mimics the free chat gpt ? i need to do a benchmark vs my RAG

API
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Which model on the api mimics the free chat gpt ? i need to do a benchmark vs my RAG
thank you very much.
asking chat gpt itself has yielded some weird answers like gpt 4o mini but that can’t be can it ?

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ChatGPT’s free tier doesn’t map to a single fixed API model — OpenAI updates it over time. To benchmark against “free ChatGPT,” the closest matches are:

  • gpt-5-chat-latest (strongest, likely what ChatGPT defaults to now)

  • gpt-4o (flagship omni model)

  • gpt-4o-mini (fast, low-cost, often used in ChatGPT for lighter queries)

Don’t rely on ChatGPT’s self-reporting (it can be misleading). Instead, check /v1/models in the API to see what’s available. For a fair RAG benchmark, test at least one “full” model (GPT-5 or GPT-4o) and one lightweight model (gpt-4o-mini) — then compare accuracy, hallucinations, latency, and cost.

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