CSV to JSON Converter
Paste CSV or open a .csv file and get clean JSON as you type. The delimiter is detected, the first row can become object keys, and numbers with a decimal comma from European Excel files are read correctly.
- Free
- No upload
- No sign-up
CSV to JSON and JSON to CSV
Quoted fields, line breaks inside cells, semicolon CSV from Excel and JSON Lines are handled.
Base64 encoder and decoder
UTF-8 safe for accents and emoji. Decoding ignores line breaks and missing padding.
Color converter: HEX, RGB and HSL
Type or paste a color in any field, or use the picker. All formats update together.
WCAG contrast
AA needs 4.5:1 for normal text and 3:1 for large text (24px, or 19px bold). AAA needs 7:1 and 4.5:1.
Number base converter
Binary, octal, decimal and hexadecimal. Very large and negative whole numbers are supported.
Spaces and underscores are ignored, and the prefixes 0b, 0o and 0x are accepted. Negative numbers keep a minus sign; for values that fit in 8 to 128 bits the two’s complement form is shown too.
Text case converter
Accented letters such as á, ž and ľ are kept, and ß becomes ẞ in capitals. Code cases are applied line by line.
URL encoder and decoder
Percent-encode text for links and query strings, or decode %20-style text back.
Component encodes every reserved character (/ ? & = #), for a single query value or path part. Full URL keeps the URL structure readable.
Unix timestamp converter
Seconds or milliseconds are detected automatically from the number of digits.
Current Unix time: —
Without Z or an offset such as +02:00, the date is read in your time zone (local).
- Unix time (seconds)
—- Unix time (milliseconds)
—- ISO 8601, UTC
—- ISO 8601, your time zone
—- Readable, your time zone
—- Relative
—
Runs entirely in your browser. Your data, files and text are never uploaded.
How the CSV is turned into JSON
With "First row is the header" switched on, each following line becomes a JSON object whose keys are the column names, so a spreadsheet of customers turns into an array like [{"name": "Ana", "city": "Bratislava"}]. Switch it off to get an array of arrays that keeps every row exactly as it is.
The parser follows RFC 4180: quoted cells may contain commas, semicolons, doubled quotes and even line breaks. It guesses the delimiter from the first 50 lines, choosing between comma, semicolon, tab and pipe, and you can always override it.
Values that look like numbers or true/false become real JSON numbers and booleans, unless that would change them: a leading zero as in 007, a phone number with a plus sign or an integer too big for JavaScript stays text. In semicolon files the decimal comma is understood, so 1,5 becomes 1.5.
How to use the CSV to JSON Converter
- Paste your CSV into the input, open a .csv or .tsv file, or drop the file onto the input area.
- Check the detected delimiter and whether the first row holds the column names.
- Choose how numbers are read and whether the JSON is pretty-printed or minified.
- Copy the JSON or download it as a .json file.
Frequently asked questions
How do I convert an Excel spreadsheet to JSON?
In Excel use File › Save As › CSV UTF-8, then open that file here. Semicolon-separated files saved by European versions of Excel are detected automatically.
Why are some numbers kept as text?
Values such as 007, +421 900 123 456 or a 20-digit ID would change if they became numbers, so they are kept as strings. Choose "Keep everything as text" to turn off number detection completely.
What if my CSV has line breaks inside a cell?
Cells in double quotes may contain line breaks, delimiters and quotes written as two quotes. They are read as part of the cell, exactly as Excel and Google Sheets write them.
How large can the CSV file be?
Up to 5 MB, which is tens of thousands of rows. Large files are converted in a background worker, so the page stays responsive while you wait.
Is my CSV data uploaded?
No. The conversion runs in this browser tab; customer lists, exports and other data never leave your device.
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