GPT-5.5
by OpenAI
OpenAI’s spring 2026 release, shipped in an “Instant” variant, sitting between GPT-5.3 Codex and the GPT-5.6 line.
Part of the GPT-5 series.
Timeline
| Date | Event |
|---|---|
| 2026-03-11 | Anonymous “Hunter Alpha” / “Healer Alpha” stealth models appear, widely suspected to be GPT-5.5 |
| 2026-03-25 | Reported feature-complete |
| 2026-06-26 | GPT-5.5 Instant ships — the variant most coverage focuses on |
| 2026-06 → 2026-07 | Paired with GLM-5.2 in popular coding workflows |
Notes
GPT-5.5 followed OpenAI’s now-familiar pattern of stealth-testing under codenames on public
arenas before launch — “Hunter Alpha” and “Healer Alpha” circulated for two weeks before being
identified. The Instant variant drove adoption, emphasising latency over maximum capability.
Notably, the strongest practitioner coverage pairs it with an open-weight model rather than
against one: “GLM-5.2 + GPT-5.5” was promoted as a best-of-both coding workflow, using the
cheaper open model for bulk work and GPT-5.5 for hard passes.