Does this tool output CSV or XLSX?

It produces .xlsx, which opens cleanly in Excel, Google Sheets, and LibreOffice. If a system specifically needs CSV, open the downloaded .xlsx and use Save As / Download as CSV - that way the data is correct in the workbook first, and you export to CSV only as the last step.

Why do leading zeros disappear in CSV but not XLSX?

CSV stores no data types, so a value like 007 is just the characters 0-0-7. When a spreadsheet app reopens the CSV it guesses the type, reads it as the number 7, and drops the leading zeros. XLSX stores the cell as text, so 007 stays exactly 007.

Will a 19-digit ID survive in a CSV?

Not reliably. Reopened in Excel, a long numeric string in CSV is often read as a floating-point number and shown in scientific notation or with its final digits zeroed. In XLSX the value is written as text, so every digit is preserved.

Can a CSV hold multiple sheets?

No. CSV is a single flat table by definition. When your JSON has two or more top-level lists of objects, XLSX can place each on its own tab; with CSV you would need a separate file per table.

When should I still choose CSV?

When a program, database loader, or data pipeline needs to ingest the data, or when a tool only accepts CSV. For those machine-to-machine cases CSV's simplicity is an advantage; for a human opening the file, XLSX avoids the type and delimiter pitfalls.

JSON to CSV vs Excel (XLSX): Which Should You Use?

Last updated: 13 June 2026

When you convert JSON to a spreadsheet, you pick between two targets: CSV (a plain-text table) or Excel / XLSX (a real workbook). They look almost identical once open, but they store data very differently - and that difference decides whether your IDs, dates, and leading zeros survive. Here's how to choose.

Quick answer

Use Excel (XLSX) when a human will open the file: real number and date types, long IDs that must not get mangled, multiple sheets, and no "which delimiter or encoding?" guessing. Use CSV when a program or database needs to import the data, or when a tool only accepts CSV. This converter produces .xlsx; from there you can always Save As CSV if a system needs it.

CSV vs XLSX at a glance

What matters	CSV	Excel (XLSX)
Data types	None - every value is plain text	Numbers, dates, text, and booleans kept distinct
Leading zeros (007)	Often lost when reopened in Excel	Preserved as text - 007 stays 007
Big numeric IDs	Risk of scientific notation / dropped digits	Every digit kept (big-number-safe)
Multiple sheets	No - one table per file	Yes - one tab per top-level list
Formulas / leading =	A value like =1+1 may execute on open	Written as a text cell, not evaluated
Delimiter / encoding	Commas in values and UTF-8 vs ANSI can break it	No delimiter or encoding guessing
File size	Smaller, plain text	Slightly larger (zipped XML)
Best for	Importing into a program or database	A person opening, filtering, and sharing

Where CSV quietly loses data

CSV has no concept of types - every cell is text until something reopens the file and guesses. That guessing is where data breaks. A ZIP or account code like 007890 loses its leading zeros, a 19-digit order ID turns into scientific notation, and a value beginning with = can be treated as a formula. None of these throw an error, so the corruption is easy to ship without noticing. The converter comparison shows these exact failures side by side.

Where XLSX is safer for people

Preserves numbers, dates, and text without any delimiter or encoding ambiguity.
Supports multiple sheets - when your JSON has two or more top-level lists of objects, each becomes its own tab.
Keeps long numeric IDs intact, with every digit.
Ready to filter, sort, and pivot the moment it opens.

Nested JSON has to be flattened either way

CSV and XLSX are both flat, so nested JSON must be flattened for either target. By default this converter spreads nested objects into dotted columns (user.address.city); switch to JSON in one cell to keep a subtree as text. Lists of values become a comma-separated cell, and lists of objects are kept as JSON text in a single cell. The nested JSON to Excel guide covers that flattening in detail.

Convert your JSON now

Drop or paste your JSON into the converter to get a ready-to-open .xlsx in seconds - free, no signup, processed in your browser. If you specifically need CSV, open the downloaded file in Excel or Google Sheets and use Save As / Download as CSV.

Frequently asked questions

Does this tool output CSV or XLSX?: It produces .xlsx, which opens cleanly in Excel, Google Sheets, and LibreOffice. If a system specifically needs CSV, open the downloaded .xlsx and use Save As / Download as CSV - that way the data is correct in the workbook first, and you export to CSV only as the last step.
Why do leading zeros disappear in CSV but not XLSX?: CSV stores no data types, so a value like 007 is just the characters 0-0-7. When a spreadsheet app reopens the CSV it guesses the type, reads it as the number 7, and drops the leading zeros. XLSX stores the cell as text, so 007 stays exactly 007.
Will a 19-digit ID survive in a CSV?: Not reliably. Reopened in Excel, a long numeric string in CSV is often read as a floating-point number and shown in scientific notation or with its final digits zeroed. In XLSX the value is written as text, so every digit is preserved.
Can a CSV hold multiple sheets?: No. CSV is a single flat table by definition. When your JSON has two or more top-level lists of objects, XLSX can place each on its own tab; with CSV you would need a separate file per table.
When should I still choose CSV?: When a program, database loader, or data pipeline needs to ingest the data, or when a tool only accepts CSV. For those machine-to-machine cases CSV's simplicity is an advantage; for a human opening the file, XLSX avoids the type and delimiter pitfalls.

Related guides

See all guides or the FAQ.

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