JSONL Viewer

A small desktop Electron app for viewing and inspecting .jsonl / .ndjson (JSON Lines) files.

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Installers for macOS, Windows and Linux are on the latest release.

The builds are unsigned, so macOS shows an unidentified-developer prompt on first open — right-click the app and choose Open — and Windows SmartScreen shows an unknown-publisher prompt.

Run from source

npm install
npm start

For development with detached DevTools:

npm run dev

Then click Open File (or drag a file in) and pick sample.jsonl from this repo, or any of your own .jsonl / .ndjson / .json / .log / .txt files. Hugging Face session traces from STS, Pi, Codex, Claude Code, and Hermes are detected automatically and open in the Traces view. The toolbar's Traces menu also finds recent sessions in the standard Codex, Claude Code, Pi, and Hermes locations.

More

• Features
• Building installers