Working with large JSONL files in the browser

JSON Lines stores one JSON object per line, which makes it useful for datasets and application logs. Large files can be unwieldy in ordinary editors. jsonl.co is a free online viewer and editor built for JSONL and NDJSON files, including files over 1GB. It streams content in chunks and renders visible rows in the browser.

A side-by-side interface shows raw lines and parsed JSON with synchronized scrolling, syntax highlighting and real-time line-by-line validation. Users can search, edit or delete rows, use find and replace, and export the result. Supported formats include .jsonl, .ndjson, .json and .txt.

Additional in-browser utilities convert JSONL to JSON, CSV, Excel and YAML, and provide formatting, validation, splitting, merging and JSON flattening. The site works locally: files are not uploaded, no account is needed, and the tools are free. That can make it useful for inspecting datasets and NDJSON logs while keeping their contents in the browser.