How to use it
- Paste your data into JSON array of objects. A single object works too.
- Choose the Separator between values. Pick Semicolon (;) if your Excel expects semicolons.
- Leave Flatten nested objects ticked to split nested objects into columns, or untick it to write them as JSON text.
- Check Validity, then copy the CSV text or download it as data.csv.
How the columns and rows are made
Each object becomes one row. The columns are all the names found in the objects, in the order they first appear. An object that lacks a name leaves that cell empty. A text value is written as text, a number exactly as typed, true and false as words, and null as an empty cell.
- With flattening on, an object inside an object becomes one column per name: address with zip becomes the column address.zip. An empty object is written as {}.
- An array is always written as JSON text, such as ["json","csv"], because one cell holds one value.
- A name that appears twice in the same object is refused, because one column cannot hold two values.
Quoting and separators (RFC 4180)
RFC 4180 describes the usual form of CSV. Lines end with CRLF. A field that contains the separator, a double quote or a line break is wrapped in double quotes, and each double quote inside it is written twice.
Turkish Excel expects semicolons between values. A file that uses commas opens with every line in one column, so choose the semicolon separator for it. The file starts with a byte order mark, so letters such as ş, ğ, ı and İ are read correctly.
Worked example: two people, one of them with a nested object
The default text has two objects. The first has an address with a zip code. The second has no city or address, and its note contains quotes, and its name contains a comma.
The header row lists the names in the order they first appear: id, name, city, address.zip and note. The second row keeps its comma inside quotes, and the quotes around the word hello are written twice.
| Line | What is written |
|---|---|
| 1 | id,name,city,address.zip,note |
| 2 | 1,Ayşe Yılmaz,Istanbul,34000, |
| 3 | 2,"Mehmet, Ali",,,"Said ""hello""" |
Frequently asked questions
Why does my CSV open in one column in Excel?
Excel takes the separator from your regional settings. Where it expects semicolons, a file that uses commas puts each whole line in one column. Choose Semicolon (;) as the separator and convert again.
Why is there a strange character at the start of the file?
It is the byte order mark, an invisible character that tells Excel and other programs that the file is UTF-8. It keeps letters such as ş, ğ, ı and İ correct when the file opens.
Are numbers rounded when they are converted?
No. A number is written exactly as it was typed in the JSON, so an ID such as 12345678901234567890 keeps every digit.
What happens to arrays inside an object?
An array becomes JSON text in one cell, for example ["json","csv"], with its double quotes doubled as RFC 4180 requires. Nothing is lost, but a spreadsheet cannot sort its items separately.
Why is a name that appears twice in one object refused?
A column holds one value per row. An object with the same name twice has no single value for that column, so the tool asks you to remove one of them.
Is my data uploaded anywhere?
No. The conversion runs in your browser, and nothing you paste is sent to our server.
Sources
- RFC 4180: Common Format and MIME Type for Comma-Separated Values (CSV) Files
- RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format
Figures and text last checked on Tuesday, November 10, 2026.