JSONL Merger
Combine several JSONL files into one, in the order you select them. Missing final newlines and byte order marks are handled, which is where plain concatenation goes wrong.
Runs entirely in your browser. Your file is never uploaded. How this works
Frequently asked questions
- Why not just use cat?
- If a file has no final newline, cat joins its last record to the next file’s first record on one line, which breaks both. This tool adds the missing newline.
- Does this remove duplicates?
- No. Every line is kept. Use the validator to find duplicate custom_id values.
- In what order are files merged?
- In the order your browser provides them, which is usually the order you selected them or alphabetical.