Claude Instant 1.2vsGPT-5.3-Codex-Spark
Claude Instant 1.2 | GPT-5.3-Codex-Spark | |
|---|---|---|
| Specifications | ||
Context windowHow much text the model can hold in mind at once — your question, any documents you attach, the conversation so far, and its own reply. Go past it and the earliest part falls out of view. | 100k | 128k |
| BenchmarksPublished by one model only | ||
HumanEvalFunction synthesis — 164 small Python problems: the AI is given a function's description and has to write the working function. This was the coding benchmark of the GPT-3.5 and GPT-4 era, before the field moved to fixing real bugs in real repositories. Higher is better. | 58.7% | — |
GSM8KGrade-school math — Grade-school maths word problems that take a few steps of arithmetic to work through. It separated the models of 2022 and 2023 sharply, then saturated. One caveat on the historical numbers: OpenAI included part of the GSM8K training set in GPT-4's pre-training mix, so GPT-4's score is not a clean few-shot result. Higher is better. | 86.7% | — |
| Overview | ||
| Company | Anthropic | OpenAI |
| Release date | Aug 9 2023 | Feb 12 2026 |
| Access | Proprietary | Proprietary |
Other comparisons
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Frequently asked questions
Claude Instant 1.2 and GPT-5.3-Codex-Spark don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Claude Instant 1.2 shipped 918 days before GPT-5.3-Codex-Spark, so benchmark comparisons should account for the intervening progress.
Context windows are 100k (Claude Instant 1.2) vs 128k (GPT-5.3-Codex-Spark).
Direct benchmark comparisons are unavailable — Claude Instant 1.2 and GPT-5.3-Codex-Spark don't publish scores on any of the same benchmarks.
Claude Instant 1.2 was released by Anthropic on Aug 9 2023.
GPT-5.3-Codex-Spark was released by OpenAI on Feb 12 2026.
Claude Instant 1.2 has a 100k context window; GPT-5.3-Codex-Spark has 128k.