TSV / Excel Paste to JSON

Yes — that is the main reason this exists separately from the CSV converter. When you copy cells from a spreadsheet, what actually lands on the clipboard is tab-separated text, not CSV. Pasting that into a comma-based converter produces one enormous column per row, which is confusing enough that people assume the tool is broken. This one expects tabs by default, so a paste from a selection of cells works immediately with no export step and no saving to a file first.

It should not be — the parser deliberately keeps any value with a leading zero as a string, precisely because postcodes, phone numbers and product codes are identifiers rather than quantities. If a zero has genuinely disappeared, the likely culprit is the spreadsheet rather than this tool: Excel converts leading-zero values to numbers on entry and on import unless the column was formatted as text first. Check the cell in the spreadsheet before assuming the conversion is at fault.

Spreadsheets quote such cells when they put them on the clipboard, and the parser here follows RFC 4180 quoting rules, so a quoted cell containing tabs or newlines is read as the single value it is. That said, multi-line cells are the shakiest part of any clipboard round trip, because different spreadsheet applications quote them slightly differently. If a paste comes out misaligned and the data has multi-line cells, exporting to a real file is more reliable than the clipboard.

A value becomes a number only if it is entirely numeric with no leading zero, so 42 and 3.14 convert while 007 and 1-800-555 stay strings. The words true and false become booleans, the word null and empty cells become null. Anything else stays a string. You can turn inference off entirely, which is the right choice when the receiving system expects every field as a string, or when you would rather handle the conversion yourself downstream.

Yes — turn off the header option and you get positional data rather than named keys. That is occasionally what you want for a matrix of values or when column names are absent or unreliable. With the header on, the first row becomes the keys and each subsequent row becomes an object, which is the shape almost every API and JavaScript consumer expects. Duplicate header names are renamed rather than silently overwriting each other.

No. Everything runs in your browser, which matters more for this tool than most — the thing people paste here is very often a selection from a real spreadsheet containing customer records, financial figures or internal data. There is no request to any server at any point, so a paste from a confidential sheet stays entirely on your machine. You can confirm it by watching the network tab while you use it.