GPT-4o is a multimodal AI model developed by OpenAI.

Is GPT-4o open source?

No, GPT-4o is a proprietary model with closed weights.

What is GPT-4o's context window?

GPT-4o supports a context window of 128,000 tokens.

OpenAIMULTIMODAL Proprietary

GPT-4o (May 2024) is the original multimodal workhorse, now legacy — kept mainly for vision/voice pipelines that newer cheap text models can't cover.

Now a legacy model — for new multimodal work use a GPT-5.x model instead.
Pricier output and smaller 128K context than GPT-4.1 and the GPT-5 line — rarely the economical pick today.
If you only need text, GPT-4.1 or GPT-5.4 mini beats it on price and quality.

Representative public scores (approximate, higher is better) for relative comparison. Check the provider for the latest official results.

MMLU89

API ~$2.50 / 1M input, ~$10 / 1M output. API-only legacy; full text+vision+audio input.