JSONL Pretty Editor

View and edit JSONL files with pretty-printed, syntax-highlighted JSON in VS Code.

Features

Pretty-print all entries — Opens .jsonl / .ndjson files with every JSON object formatted and syntax-highlighted using CodeMirror 6
Edit inline — Modify any entry directly in the pretty-printed view
Saves as JSONL — On save, each entry is serialized back to a single line of compact JSON
Add / Delete entries — Buttons to add new entries or remove existing ones
Collapse / Expand — Collapse individual entries or all at once for easier navigation
Validation — Invalid JSON entries are highlighted with a red border and error message
Theme-aware — Automatically matches VS Code's dark/light theme

Install the extension and reopen any .jsonl files that were already open (or reload the window with Ctrl+Shift+P → "Reload Window")
New .jsonl / .ndjson files will automatically open in the pretty editor
Edit entries directly in the formatted view
Save with Ctrl+S / Cmd+S — the file is written as proper JSONL

If a .jsonl file opens in the plain text editor, use Ctrl+Shift+P → "Open with JSONL Pretty Editor" to switch.

To open the raw text instead, right-click the file → Open With... → Text Editor.

npm install
npm run build:all

Press F5 in VS Code to launch the Extension Development Host.