WhichAI / Models / GPT-5.5

GPT-5.5

· verified September 8, 2026

public free paid api in Generator coding reasoning writing

Provider

Statuspublic

AA Intelligence Index56.3 (September 8, 2026 snapshot)

Released2026-04

Context windown/a

Modalitiesn/a

API price $/1M (in / out)n/a

Speedn/a

AccessFree (limited messages) · Plus $20/mo · Go ~$8/mo · API

In one line

The April 2026 flagship, still the strongest broad generalist most people can use free: brainstorming, drafting, frontier coding (SWE-bench Verified 88.7%).

Coding88

Reasoning86

Writing82

Agents & tools84

Category scores (0-100) are WhichAI blended ratings: public category leaderboards plus editorial judgment. Guidance, not official measurements.

Alternatives worth a look

Gemini 3.7 Flash (Google) · AA 56Released August 13, 2026 · API $0.75/$3.75 per 1M tokens (introductory, doubles Jan 1, 2027) · model id gemini-3.7-flash · free-tier availability not confirmed
GPT-5.6 Terra (OpenAI) · AA 56.6Released July 9, 2026 · API $2.50/$15 per 1M tokens
Grok 4.5 (xAI) · AA 55.8Released July 8, 2026 · API $2/$6 per 1M tokens · in Grok Build & Cursor · not yet in the EU

Head-to-head: GPT-5.5 vs Claude Sonnet 5 · GPT-5.5 vs Claude Opus 4.8

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Artificial Analysis Intelligence Index, 2026 rebased scale (top models ~ 55-66). Snapshot: September 4, 2026 (BenchLM mirror), retrieved September 8, 2026. Specs and prices come from the OpenRouter public model list on the same date. Models nobody has measured carry no index score at all and never enter a ranking: where an estimate exists it is shown separately and labelled unmeasured. Context, price, modality and release dates come from the public OpenRouter model list (retrieved September 8, 2026) and vendor pages. Missing values are not published or not yet verified - shown as -. Sources are linked inside the app (Model guide and About > Methodology).