Which AI model writes the most bugs in PHP?

As of Nov 14, 2026, Claude Fable 5.1 had the highest relative bug rate in PHP code (2.55, 155% more counted bugs than the PHP average).

Updated Nov 14, 2026

Best AI model for PHP code

As of Nov 14, 2026, Claude Opus 5.5 had the lowest relative bug rate in PHP code (0.82, 18% fewer counted bugs than the PHP average), among 2 ranked models.

Models ranked by relative bug rate in PHP code. Lower values are better.
Rank	Model	Rate
1	Claude Opus 5.5	0.82
2	Claude Fable 5.1	2.55

1.00 = PHP average · lower is better

Other languages

TypeScript
Python
JavaScript
SQL
Go
Shell
Rust
Swift
Ruby
Vue
Terraform
C#
Svelte
Java
Kotlin
Dart
Elixir

Questions and answers

Which AI model writes the most bugs in PHP?: As of Nov 14, 2026, Claude Fable 5.1 had the highest relative bug rate in PHP code (2.55, 155% more counted bugs than the PHP average).