Format, inspect, and filter newline-delimited JSON (NDJSON) or JSON Lines (.jsonl) datasets instantly and securely in your browser.
Drop NDJSON/JSONL file here
Formatted JSON lines will appear here
Paste or drop your NDJSON or JSON Lines file to instantly format, validate, and inspect every line.
Paste NDJSON/JSONL data or drop a .ndjson, .jsonl, .log, or .txt file into the left panel.
The stats bar shows total lines, valid frames, errors, and estimated file size. Each line is formatted independently.
Copy the formatted output, download it as a file, or send all valid frames as a JSON array to the JSON Formatter.
A: Yes, completely free and runs 100% in your browser.
A: All processing happens locally. No data is ever sent to any server.
A: Any newline-delimited text file: .ndjson, .jsonl, .log, .txt
A: Invalid lines are flagged in the output with an (INVALID JSON) label. Valid lines are still formatted normally.
Working with large NDJSON logs or JSON Lines files is painful in a standard editor. This tool gives you line-by-line validation and formatting instantly.
Privacy First
Your data never leaves your browser. All parsing and formatting happens locally.
Line-by-Line Validation
Each JSON line is independently parsed. Invalid lines are flagged without disrupting the rest of the output.
Send to Formatter
Convert all valid NDJSON frames into a single JSON array and open it in the full JSON Formatter with one click.