Which AI model writes the most bugs in Kotlin?

As of Sep 30, 2026, GPT-5.6 Sol had the highest relative bug rate in Kotlin code (1.21, 21% more counted bugs than the Kotlin average), statistically tied with Claude Opus 4.8.

Updated Sep 30, 2026

Best AI model for Kotlin code

As of Sep 30, 2026, Claude Opus 5 had the lowest relative bug rate in Kotlin code (0.63, 37% fewer counted bugs than the Kotlin average), among 3 ranked models.

Models ranked by relative bug rate in Kotlin code. Lower values are better.
Rank	Model	Rate
1	Claude Opus 5	0.63
2= (statistically tied)	Claude Opus 4.8	0.90
3= (statistically tied)	GPT-5.6 Sol	1.21

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

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Questions and answers

Which AI model writes the most bugs in Kotlin?: As of Sep 30, 2026, GPT-5.6 Sol had the highest relative bug rate in Kotlin code (1.21, 21% more counted bugs than the Kotlin average), statistically tied with Claude Opus 4.8.