OpenAI releases o3, its most powerful reasoning model, and o4-mini, a smaller model optimized for fast, cost-efficient reasoning.
OpenAI released o3, called its most advanced reasoning model, and o4-mini, a cost-efficient reasoning model, on 16 April 2025, with o4-mini-high, to ChatGPT Pro, Plus and Team users[1][2][3]
OpenAI planned o3-pro for ChatGPT Pro in the coming weeks (released 10 June 2025); Altman indicated o3 and o4-mini might be the last stand-alone reasoning models before GPT-5[1][2][3]
o3 was originally announced on 20 December 2024; OpenAI later announced its ChatGPT retirement for 26 August 2026, with the API unaffected[1][2]
Notable features
They were the first models able to 'think with images' (whiteboard sketches, zooming and rotating while reasoning) and can use ChatGPT tools including web browsing, Python and image generation[3]
OpenAI says o3 set new state-of-the-art results on Codeforces, SWE-bench and MMMU and made 20 percent fewer major errors than o1 on difficult real-world tasks in external expert evaluations; both models were trained with reinforcement learning to reason about when and how to use tools[4]
o4-mini was the best-performing benchmarked model on AIME 2024 and 2025, scoring 99.5% pass@1 on AIME 2025 with a Python interpreter (o3 98.4%), and supports significantly higher usage limits than o3[4]
They were also added to the Chat Completions and Responses APIs: o3 at $10 per million input and $40 output tokens, o4-mini at $1.10 and $4.40[3]
On SWE-bench Verified TechCrunch reports o3 at 69.1% and o4-mini at 68.1%, against o3-mini at 49.3% and Claude 3.7 Sonnet at 62.3%[3]
The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
web.archive.org· Published Apr 16, 2025· 6% of score
Archived copy of OpenAI's[1] o3 and o4-mini announcement, which says o3 "sets a new SOTA on benchmarks including Codeforces, SWE-bench ... and MMMU", makes "20 percent fewer major errors than OpenAI o1", and o4-mini "achieves 99.5% pass@1" on AIME 2025 with Python.
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CONFIRMED89% CONFIDENCE320 days agoDated from the release notes leave this entry undated; the Codex changelog dates GPT-5-Codex-Mini's introduction Nov 7, 2025[1]
OpenAI adds GPT-5-Codex-Mini, a smaller, cheaper GPT-5-Codex with about 4x more usage, to the Codex CLI and IDE extension.
SCHEDULED80% CONFIDENCEin 79 daysOpenAI's[1][2] own deprecation page, announced 2026-06-11, gives the shutdown date as 11 December 2026. A shutdown date is the vendor's commitment to developers and is occasionally pushed back, never brought forward.
OpenAI switches off 6 models and endpoints on 11 December 2026; requests to them stop working and callers have to move to the named replacements. Going: gpt-5-2025-08-07, gpt-5-mini-2025-08-07, gpt-5-nano-2025-08-07, gpt-5-pro-2025-10-06, o3-2025-04-16, o3-pro-2025-06-10.
