GPT-5.5

openai.com

1234 points by rd 12 hours ago


tedsanders - 11 hours ago

Just as a heads up, even though GPT-5.5 is releasing today, the rollout in ChatGPT and Codex will be gradual over many hours so that we can make sure service remains stable for everyone (same as our previous launches). You may not see it right away, and if you don't, try again later in the day. We usually start with Pro/Enterprise accounts and then work our way down to Plus. We know it's slightly annoying to have to wait a random amount of time, but we do it this way to keep service maximally stable.

(I work at OpenAI.)

simonw - 10 hours ago

This doesn't have API access yet, but OpenAI seem to approve of the Codex API backdoor used by OpenClaw these days... https://twitter.com/steipete/status/2046775849769148838 and https://twitter.com/romainhuet/status/2038699202834841962

And that backdoor API has GPT-5.5.

So here's a pelican: https://simonwillison.net/2026/Apr/23/gpt-5-5/#and-some-peli...

I used this new plugin for LLM: https://github.com/simonw/llm-openai-via-codex

UPDATE: I got a much better pelican by setting the reasoning effort to xhigh: https://gist.github.com/simonw/a6168e4165a258e4d664aeae8e602...

jfkimmes - 11 hours ago

Everyone talked about the marketing stunt that was Anthropic's gated Mythos model with an 83% result on CyberGym. OpenAI just dropped GPT 5.5, which scores 82% and is open for anybody to use.

I recommend anybody in offensive/defensive cybersecurity to experiment with this. This is the real data point we needed - without the hype!

Never thought I'd say this but OpenAI is the 'open' option again.

Someone1234 - 11 hours ago

I'd like to draw people's attention to this section of this page:

https://developers.openai.com/codex/pricing?codex-usage-limi...

Note the Local Messages between 5.3, 5.4, and 5.5. And, yes, I did read the linked article and know they're claiming that 5.5's new efficient should make it break-even with 5.4, but the point stands, tighter limits/higher prices.

astlouis44 - 12 hours ago

A playable 3D dungeon arena prototype built with Codex and GPT models. Codex handled the game architecture, TypeScript/Three.js implementation, combat systems, enemy encounters, HUD feedback, and GPT‑generated environment textures. Character models, character textures, and animations were created with third-party asset-generation tools

The game that this prompt generated looks pretty decent visually. A big part of this likely due to the fact the meshes were created using a seperate tool (probably meshy, tripo.ai, or similiar) and not generated by 5.5 itself.

It really seems like we could be at the dawn of a new era similiar to flash, where any gamer or hobbyist can generate game concepts quickly and instantly publish them to the web. Three.js in particular is really picking up as the primary way to design games with AI, in spite of the fact it's not even a game engine, just a web rendering library.

khutorni - 6 minutes ago

> One engineer at NVIDIA who had early access to the model went as far as to say: "Losing access to GPT‑5.5 feels like I've had a limb amputated.”

That's a wild statement to put into your announcement. Are LLM providers now openly bragging about our collective dependency on their models?

minimaxir - 12 hours ago

The more interesting part of the announcement than "it's better at benchmarks":

> To better utilize GPUs, Codex analyzed weeks’ worth of production traffic patterns and wrote custom heuristic algorithms to optimally partition and balance work. The effort had an outsized impact, increasing token generation speeds by over 20%.

The ability for agentic LLMs to improve computational efficiency/speed is a highly impactful domain I wish was more tested than with benchmarks. From my experience Opus is still much better than GPT/Codex in this aspect, but given that OpenAI is getting material gains out of this type of performancemaxxing and they have an increasing incentive to continue doing so given cost/capacity issues, I wonder if OpenAI will continue optimizing for it.

6thbit - 10 hours ago

                          Mythos     5.5
    SWE-bench Pro          77.8%*   58.6%
    Terminal-bench-2.0     82.0%    82.7%*
    GPQA Diamond           94.6%*   93.6%
    H. Last Exam           56.8%*   41.4%
    H. Last Exam (tools)   64.7%*   52.2%    
    BrowseComp             86.9%    84.4%  (90.1% Pro)*
    OSWorld-Verified       79.6%*   78.7%

Still far from Mythos on SWE-bench but quite comparable otherwise. Source for mythos values: https://www.anthropic.com/glasswing
silvertaza - 10 hours ago

Still huge hallucination rate, unfortunately at 86%. To compare, Opus sits at 36%.

Source: https://artificialanalysis.ai/models?omniscience=omniscience...

applfanboysbgon - 12 hours ago

If there's a bingo card for model releases, "our [superlative] and [superlative] model yet" is surely the free space.

mudkipdev - 10 hours ago

This is 3x the price of GPT-5.1, released just 6 months ago. Is no one else alarmed by the trend? What happens when the cheaper models are deprecated/removed over time?

vthallam - 11 hours ago

This model is great at long horizon tasks, and Codex now has heartbeats, so it can keep checking on things. Give it your hardest problem that would take hours with verifiable constraints, you will see how good this is:)

*I work at OAI.

_alternator_ - 9 hours ago

> One engineer at NVIDIA who had early access to the model went as far as to say: "Losing access to GPT‑5.5 feels like I've had a limb amputated.”

This quote is more sinister than I think was intended; it likely applies to all frontier coding models. As they get better, we quickly come to rely on them for coding. It's like playing a game on God Mode. Engineers become dependent; it's truly addictive.

This matches my own experience and unease with these tools. I don't really have the patience to write code anymore because I can one shot it with frontier models 10x faster. My role has shifted, and while it's awesome to get so much working so quickly, the fact is, when the tokens run out, I'm basically done working.

It's literally higher leverage for me to go for a walk if Claude goes down than to write code because if I come back refreshed and Claude is working an hour later then I'll make more progress than mentally wearing myself out reading a bunch of LLM generated code trying to figure out how to solve the problem manually.

Anyway, it continues to make me uneasy, is all I'm saying.