Which AI model writes the most bugs in PHP?

As of Sep 30, 2026, Claude Opus 5.5 had the highest relative bug rate in PHP code (3.47, 247% more counted bugs than the PHP average).

Updated Sep 30, 2026

Best AI model for PHP code

As of Sep 30, 2026, Claude Opus 4.8 had the lowest relative bug rate in PHP code (0.39, 61% fewer counted bugs than the PHP average), among 4 ranked models.

Models ranked by relative bug rate in PHP code. Lower values are better.
Rank	Model	Rate
1	Claude Opus 4.8	0.39
2= (statistically tied)	Claude Sonnet 5	0.72
3= (statistically tied)	Claude Opus 5	0.72
4	Claude Opus 5.5	3.47

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

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Questions and answers

Which AI model writes the most bugs in PHP?: As of Sep 30, 2026, Claude Opus 5.5 had the highest relative bug rate in PHP code (3.47, 247% more counted bugs than the PHP average).