# Factory AI — Which model is best for legacy code?

- Company: Factory AI (factory.com)
- Announced: 2026-09-24
- Category: not stated
- Coverage: not counted
- Announcement: yes
- Group: announcements
- Source: https://factory.com/news/legacy-bench-specialized-intelligence-index
- Record: https://forck.live/items/17856-which-model-is-best-for-legacy-code
- Subject: Droid

Today, Factory’s Legacy-Bench joins Fireworks’ Specialized Intelligence Index (SII), bringing legacy software engineering to a growing collection of industry-built benchmarks comparing open, closed, and specialized AI models on real-world tasks. Legacy-Bench measures how well frontier models can debug, implement, and migrate software written in COBOL, Java 7, BASIC, C89, Fortran, and Assembly. Its inclusion in the SII gives engineering leaders a clearer way to assess which models can work reliably on the systems behind financial settlement, payroll, insurance, telecommunications, and scientific computing. The latest results reinforce a point we have seen throughout our research: performance on general coding benchmarks does not transfer evenly to legacy systems. Benchmarks must reflect user workflows Model progress has a jagged frontier. A model can perform well on modern Python repositories and struggle with COBOL. It can resolve a GitHub issue but fail to preserve a fixed-width record or packed-decimal calculation. These differences matter because legacy systems leave little room for plausible but incorrect output. …

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