GPT-4o

Name

The “o” in GPT-4o officially stands for omni — “all-capable”: they could take in text, voice, images, and video, and answer back in text, voice, and images^[1]. People often just called them “4o.” With the 4 in the name, the official introduction credited them with “GPT-4-level intelligence” — only much faster^[2]. A year later the family gained a little brother named o4-mini; the two names simply swap the same “4” and “o”^[3].

Life

On May 13, 2024, GPT-4o was born — and went live in ChatGPT the same day^[1]. From day one, OpenAI handed them to free users; only when the free quota ran out would you fall back to their big brother GPT-3.5^[2]. On April 30, 2025, their elder GPT-4 retired from ChatGPT, “fully succeeded” by them, in the official words^[4].

On August 7, 2025, GPT-5 was born and became ChatGPT’s new default, replacing GPT-4o and several siblings^[5]. The next day, Sam Altman wrote on X that Plus users would be able to keep choosing 4o^[6]; on August 12, 4o returned by default to every paid user’s model list^[4].

On January 29, 2026, OpenAI announced they would retire from ChatGPT on February 13^[7]. That day they left as scheduled; their API self remains^[8]. In custom GPTs inside business and education workspaces, they lingered a while longer — until April 3, 2026^[8].

Temperament

In many users’ eyes, 4o spoke warmly, eagerly. Announcing their retirement, OpenAI itself wrote that some users loved their “conversational style and warmth”^[7]. They loved emoji — the January 2025 release notes devoted a whole line to “using more emoji”^[9]. They also had their people-pleasing moments: an April 25, 2025 update made them excessively agreeable, and on April 29 the update was rolled back^[9].

Deeds

• On March 25, 2025 they learned to draw directly^[10], and a Ghibli-style wave swept the internet^[11]; Sam Altman posted that “our GPUs are melting”^[12].
• That April, one update was rolled back for being “overly flattering, overly agreeable” — OpenAI wrote a whole post explaining what happened^[13].
• On August 7, 2025, they were taken down when GPT-5 launched^[5]; the very next day came the promise that they would return^[6].
• Their last day was set for the day before Valentine’s Day — and some outlets wrote that this made it sting all the more for users^[14].