How to Convert JSON to CSV (and Back) Without Breaking Your Data

By HSP · Published October 24, 2026 · 6 min read · Developer Guides

JSON and CSV are the two formats you meet most when data moves between apps. APIs, databases and web apps send JSON. Spreadsheets, accounting software, email tools and most "import contacts" screens want CSV. Converting between them is simple once you know what each format can and cannot hold, and where the usual surprises hide.

JSON vs CSV in one minute

Because CSV is flat and JSON is not, converting JSON to CSV always involves a decision: what happens to the nested parts? Converting back has the opposite problem: CSV does not say which values are numbers and which are text.

How to convert JSON to CSV, step by step

1. Open the JSON to CSV Converter.
2. Paste your JSON, or drop a .json file on the page. It is read on your device.
3. Pick a delimiter if you need one other than a comma (more on semicolons below).
4. Press JSON → CSV, then copy the result or press Download.

If the tool reports an error, the JSON itself is probably broken, often a missing comma or a trailing comma. Run it through the JSON formatter first, or read our guide on how to fix invalid JSON.

A worked example

Here are two customer records, with a nested city object and a list of tags:

[
  {"name": "Asha", "age": 31, "city": {"name": "Pune", "country": "India"}, "tags": ["tea", "chess"]},
  {"name": "Ben", "age": 27, "city": {"name": "Toronto", "country": "Canada"}, "note": "Likes \"quotes\", commas"}
]

Our converter turns it into this CSV:

name,age,city.name,city.country,tags,note
Asha,31,Pune,India,"[""tea"",""chess""]",
Ben,27,Toronto,Canada,,"Likes ""quotes"", commas"

Four things happened, and they are the four rules worth remembering:

• Every key becomes a column, even if only one record has it. Only Ben has a note and only Asha has tags, so the other cell is simply left empty. Columns appear in the order they are first seen.
• Nested objects are flattened with dots. city.name and city.country became their own columns.
• Arrays stay in one cell as JSON text. Splitting a list across columns would break as soon as one person had more tags than another, so the list is kept whole.
• Commas, quotes and line breaks are quoted. A cell that contains a comma, a double quote or a line break is wrapped in double quotes, and any double quote inside it is doubled (""). This is the rule described in RFC 4180, and it is what Excel, Google Sheets and LibreOffice expect.

How to convert CSV to JSON

Paste the CSV into the same tool and press CSV → JSON. By default, three options are switched on, and each one is worth understanding:

• First CSV row is the header. The first row becomes the keys. Untick it if your file has no header, and you get plain arrays instead of objects.
• Detect numbers, true/false and null. 1.50 becomes the number 1.5, and true becomes a real boolean. Untick it to keep every value as text.
• Rebuild nested objects from dot.keys. A header like user.city becomes {"user": {"city": "..."}}, so a file you flattened earlier comes back in its original shape.

The delimiter is detected automatically from the first line (comma, semicolon, tab or pipe), and quoted fields with commas or line breaks inside are read correctly.

The leading-zero trap

Postal codes, phone numbers and product codes often start with zero: 01234, 0044, 007. If they are turned into numbers, the zeros vanish and the data is quietly wrong. Our converter only treats a value as a number when it looks like a proper number, so 01234 stays the text "01234". The bigger risk is often the spreadsheet: when you double-click a CSV file, Excel may strip those zeros as it opens it. To keep them, import the file through Excel's data import (From Text/CSV) and set that column to Text, or open it in Google Sheets and check the column format.

Commas vs semicolons

In many European countries, the comma is the decimal separator (3,5 instead of 3.5), so Excel set to those regions expects CSV columns separated by semicolons. If your whole CSV lands in column A, choose Semicolon ; as the delimiter and convert again. Tabs are another safe choice when your data is full of commas.

Common problems and quick fixes

Moving data into a database instead? Our SQL formatter keeps your import queries readable, and the regex tester helps you find and clean messy values before you convert. For more developer basics, read our regex cheat sheet and how to format SQL queries.

VSH take: Most broken spreadsheets are not caused by the conversion itself but by what happens after: a double-click that strips zeros, a semicolon region setting or a file saved in the wrong encoding. Convert, then check three things: the column count, a value with a leading zero and a value with an accent. If all three look right, you are done. Studying databases or computer science? Our study tools and exam guides can help, the free games are there for a break, and if you are heading to a tech conference, compare fares on the flights hub.

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