CSV to JSON Converter

About CSV to JSON converter

The CSV to JSON converter reads delimited text and outputs a JSON array, using the header row as property names. It detects the delimiter for you, follows RFC 4180 quoting rules, and can convert numbers, booleans and null into real JSON types. The page opens with a sample so the options are easy to try.

How to use it

1. Replace the sample in the CSV box with your own text.
2. Leave the Delimiter on Auto-detect, or choose comma, semicolon, tab, pipe or Custom.
3. Turn First row is a header off if your data has no column names, and turn Convert numbers and booleans off to keep every value as text.
4. Review the JSON output, then press Copy or Download, which saves data.json.

A quoted field with a comma, plus type conversion

id,name,city,active
1,Ada Lovelace,London,true
2,Grace Hopper,"New York, NY",false

[
  {
    "id": 1,
    "name": "Ada Lovelace",
    "city": "London",
    "active": true
  },
  {
    "id": 2,
    "name": "Grace Hopper",
    "city": "New York, NY",
    "active": false
  }
]

When to use it

• Loading a spreadsheet export into a JavaScript app or a NoSQL database.
• Creating mock API responses from a table someone prepared in Excel.
• Converting a tab-separated export from an analytics tool into structured data.
• Turning a pipe-delimited feed into JSON so it can be inspected or validated.

Questions about CSV to JSON converter

How does auto-detect choose a delimiter?

It samples up to the first ten non-empty lines and tries comma, semicolon, tab and pipe. The candidate that splits every line into the same number of columns wins, so ragged data may need a manual choice.

Which values are converted when the switch is on?

The words true and false in any letter case become booleans, null becomes null, and plain numbers including decimals and exponents become numbers. An empty cell stays an empty string.

Why did 007 stay a string?

Numbers with a leading zero are treated as identifiers, such as ZIP codes and product codes, so they are not converted. A value like 1e3 does become 1000, however.

What if two columns share a name or a header is blank?

Repeats get a numeric suffix, so a second id becomes id_2, and a blank header is named column followed by its position. That keeps every key unique in each object.

What is the output without a header row?

An array of arrays, one inner array per line of the CSV, with no property names. Rows shorter than the header get empty strings, while extra cells beyond it are dropped when a header is used.

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