About This Launch
jsonl.co is a free, local-first JSONL viewer and editor that runs in the browser. It opens, views, edits and validates .jsonl, .ndjson, .json and .txt files up to 1GB, with side-by-side raw and parsed views, find and replace, and export. Files are processed on your device.
The page says 'Free Forever' and 'No sign-up, no limits, no hidden fees'. The site also lists conversion, format, validate, split and merge tools, plus guides, and links a VS Code extension.
Why I Built This
jsonl.co was built so people can open and edit very large JSONL files directly in the browser without uploading them anywhere.
Launch Details
CategoryDeveloper Tools
StageLive
ListedNovember 7, 2026