Which AI model writes the most bugs in JavaScript?

As of Sep 30, 2026, Claude Opus 5.5 had the highest relative bug rate in JavaScript code (3.02, 202% more counted bugs than the JavaScript average), statistically tied with Claude Sonnet 5.

Updated Sep 30, 2026

Best AI model for JavaScript code

As of Sep 30, 2026, Claude Opus 4.8 had the lowest relative bug rate in JavaScript code (0.53, 47% fewer counted bugs than the JavaScript average), among 7 ranked models.

Models ranked by relative bug rate in JavaScript code. Lower values are better.
Rank	Model	Rate
1	Claude Opus 4.8	0.53
2	GPT-5.6 Sol	0.91
3= (statistically tied)	Claude Opus 5	1.22
4= (statistically tied)	Claude Fable 5.1	1.44
5= (statistically tied)	GPT-6 Astra	1.51
6= (statistically tied)	Claude Sonnet 5	2.52
7= (statistically tied)	Claude Opus 5.5	3.02

1.00 = JavaScript average · lower is better · = statistically tied

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Questions and answers

Which AI model writes the most bugs in JavaScript?: As of Sep 30, 2026, Claude Opus 5.5 had the highest relative bug rate in JavaScript code (3.02, 202% more counted bugs than the JavaScript average), statistically tied with Claude Sonnet 5.