Dev Builds Own Offline Code Comparison Tool on a 15-Year-Old Laptop, Tames 23K Lines

karthikjpt · reddit · 2026-08-26

Working on a 15-year-old laptop with only a basic text editor, the developer had to reconcile three 5,000-line files with near-identical logic but different implementations—manual line-by-line comparison was error-prone and power cuts made it worse.

He spent half a day building a row-by-row visual comparator around a main reference file, then organized all 15,000 lines in hours and used AI to clean and optimize the code, ultimately restructuring 15K frontend plus 8K backend lines.

He's now turning it into a public product: 100% offline via Service Workers, privacy-first with local data, flexible cloud sync and export/import, and no installation. Competitors often charge $20+/month with heavy installs; he's asking the community for demand validation and pricing feedback.

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