I Built the Same App with Fable 5, Opus 4.8, and Sonnet 5…The Results Weren’t Even Close

Anthropic released three coding models—Fable 5, Opus 4.8, and Sonnet 5—and a developer built the same expense tracker app with each, finding significant performance differences based on prompt counts.

Member-only story I Built the Same App with Fable 5, Opus 4.8, and Sonnet 5…The Results Weren’t Even Close Anthropic now has three models that can code: - Fable 5 at the top - Opus 4.8 in the middle - And Sonnet 5 as the new free default. I built the same app on all three. I used the same spec, the same stack, and the same judgment criteria. The prompt counts tell the whole story. My Spec I used a real client spec. An expense tracker with five features: - Auth via email/password with protected routes - Dashboard with total spending, category breakdown chart, and monthly trend line - Add expense form with description, amount, category dropdown, and date picker - Expenses table with category filter and CSV export - Mobile responsive throughout The spec Remember to add your Supabase project URL and anon key : Build a team expense tracker app.Stack: React, Vite, TypeScript, Tailwind CSS, Supabase.Supabase project URL and anon key are in .env as VITE SUPABASE URL and VITE SUPABASE ANON KEY.The database…