GPT-5.5
by OpenAI
OpenAI's top flagship. Careful and thorough on hard problems — pick when you want the most considered answer regardless of cost. Try GPT-5.5 on Zo.
Knowledge cutoffDec 2025
Context window1.1M tokens
Release dateApr 2026
Input
$5.00 / 1M tokensOutput
$30.00 / 1M tokensCached
$0.50 / 1M tokensHow we rate models
- Quality. Three brains is top, one is basic. We anchor the rating on SWE-bench Verified — the industry-standard coding benchmark — how often a model solves real GitHub issues end-to-end.
- Fast. Shown when the model can produce at least roughly 80 tokens per second (about 60 words a second). Not every model qualifies.
- $$$$$$
- Cost. Single dollar is the cheapest tier (green), three dollars is the priciest (amber). We bucket models relative to the other models you can pick from on Zo, so the tier is meaningful across providers.
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