Free File & Data Tool
CSV to JSON Converter — Free Online Tool
Convert CSV files or pasted spreadsheet data into JSON in your browser. Handle quoted commas and multiline cells, choose a delimiter, preview rows, then copy or download the result.
Default: all cell values remain strings, so IDs such as 00123 retain their leading zeros.
0 data rows converted
Preview: first five data rows
This preview shows parsed cell text before optional type inference. It is limited to five rows and six columns for readability.
Data handling: This converter reads and processes the input in your browser; it does not submit CSV contents to a conversion server. Avoid pasting credentials, payment details or other sensitive records into any website unless you trust the page and its third-party scripts.
How to convert CSV to JSON
- Paste or open a CSV file. Include a header row if you want JSON objects with named properties.
- Choose your settings. Confirm the separator, indicate whether the first row is a header and keep values as strings unless you specifically need numbers or booleans.
- Convert and inspect the preview. The tool reports inconsistent row lengths or invalid quoting instead of quietly dropping records.
- Copy or download JSON. Use the result in a script, a test fixture or an application that accepts a JSON array.
CSV to JSON example with a quoted comma
A comma inside a quoted cell is part of that value, not a new column. This converter also handles doubled quotation marks and line breaks inside quoted cells.
CSV input
id,item,notes 001,Lamp,"Red, large" 002,Notebook,"Quote: ""ready"""
JSON output
[
{
"id": "001",
"item": "Lamp",
"notes": "Red, large"
},
{
"id": "002",
"item": "Notebook",
"notes": "Quote: \"ready\""
}
]Avoid common CSV conversion mistakes
Quoted commas and multiline cells
A cell such as "Red, large" is one field. A quoted address or note may contain a real line break without starting a new JSON record.
Leading zeros and type inference
Postal codes, SKUs and IDs can begin with zero. All values remain strings by default; optional inference avoids changing leading-zero numbers and identifier-like columns.
Duplicate headers and irregular rows
Duplicate or blank column names create ambiguous JSON keys. Fix them before converting. Rows with too many or too few cells produce a specific error rather than disappearing.
Semicolon and tab-separated exports
Not every spreadsheet export uses commas. Choose semicolon or tab if automatic detection does not match the file you opened.
Choose JSON objects or arrays
With “First row contains headers” selected, each data row becomes an object, such as {"id":"001","item":"Lamp"}. Without headers, each CSV row becomes a JSON array, such as ["001","Lamp"]. Headerless output includes every CSV row, including the first.
When inference is enabled, straightforward numbers, booleans and the literal null can become JSON numbers, booleans and null. Ambiguous numeric strings, unsafe integers, identifiers and leading-zero values remain strings. Always confirm the intended types for APIs and imports.
When a CSV to JSON converter is useful
Use CSV to JSON conversion for spreadsheet exports, basic API test fixtures, tabular inventory data, application prototypes or small reporting datasets. This tool creates a JSON array, not an API request or database import by itself. Check required property names and value types against the destination application's documentation.
If you need to turn a JSON array into spreadsheet rows instead, use the JSON to CSV Converter. If your output needs inspection, use the JSON Formatter and Validator after conversion.
Frequently asked questions
Can I convert a CSV file without uploading it to a server?
Yes. The file picker reads its contents locally in your browser for conversion. The website itself may still load unrelated scripts or resources; avoid sharing confidential data unless you trust the page.
Does the converter handle quotes and commas in the same cell?
Yes. It understands quoted CSV fields, doubled quotation marks and embedded newlines. A malformed quotation or mismatched row length produces an error that identifies the affected line.
Why did my number become a string in JSON?
CSV stores cells as text and some numeric-looking values are identifiers. String output is the default so values such as 00123 are not silently changed. Turn on inference only when you need typed data.
Can I convert semicolon-separated CSV or TSV?
Yes. Select automatic separator detection or choose comma, semicolon, tab or pipe manually. Confirm the detected separator in the conversion status.
What if my CSV has missing values or uneven rows?
An empty cell is an empty string by default. If one row has a different number of columns than expected, this tool stops and asks you to fix that row instead of skipping it.
How large a CSV file can I convert?
This version accepts input up to 5 MB. Processing speed and JSON output size also depend on your browser and device memory. For larger datasets, use a dedicated local data-processing application.
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