Data Format Converters
These 10 data converters move a value between formats: CSV and JSON, HTML and text, decimal and binary, letters and numbers. Each uses a real parser, so quoted commas and escaped characters survive the trip.
10 tools
- Binary ConverterConvert between binary, octal, decimal and hexadecimal in every direction, with digit grouping.
- CSV to JSON ConverterConvert CSV to JSON with a proper RFC 4180 parser that handles quoted fields and embedded commas.
- HTML to Text ConverterConvert HTML to text by stripping tags and decoding entities, with the option to keep paragraph breaks so the result reads as prose rather than one long line.
- IPv4 to IPv6 ConverterShow the mapped, compatible and 6to4 IPv6 forms of an IPv4 address, with the deprecated ones marked.
- JSON to CSV ConverterFlatten nested JSON into CSV, with dotted column names and a union of keys across all records.
- Letters to Numbers ConverterConvert letters to numbers and back using the A1Z26 scheme, where each letter maps to its position in the alphabet. Both directions run in your browser.
- Number to Words ConverterWrite numbers out in words in British or American style, including decimals and negatives.
- Punycode ConverterConvert international domain names to and from punycode, with a homograph-attack warning.
- Text to ASCII Codes ConverterConvert text to decimal, octal, hexadecimal or binary character codes, and back again.
- Text to HTML ConverterConvert plain text to HTML with paragraph detection, line breaks or escaping only.
What these data converters do
Four handle structured data. CSV to JSON and JSON to CSV move between the two formats most exports use, both built on an RFC 4180 parser so a comma inside a quoted field does not split a column. The remaining two turn HTML into plain text and plain text into HTML, with paragraph detection rather than a blanket tag strip.
Four handle numeric and character encoding. The binary converter moves between decimal, binary, octal and hexadecimal. The text to ASCII codes tool shows each character code point in four bases at once, and despite the name it covers the whole of Unicode rather than the 128 characters ASCII defines.
Two handle naming and addressing. The punycode converter turns an internationalised domain name into its ASCII form and back, which is how a domain containing non-Latin characters travels through DNS. The IPv4 to IPv6 converter shows the mapped and embedded forms of an address.
The number to words converter and the letters to numbers converter cover the two directions people most often need for cheques, cipher puzzles and spelling out figures in contracts.
Which data converter to reach for
The CSV pair and the text pair each work in both directions, so the question is which format you are starting from.
| What you have | The converter |
|---|---|
| A spreadsheet export to load into code | CSV to JSON, which keeps quoted commas and embedded line breaks intact |
| An API response to open in a spreadsheet | JSON to CSV, which flattens nested keys into dotted column names |
| Markup you want as readable prose | HTML to text, with the option to keep paragraph breaks |
| A number in the wrong base | Binary converter, covering decimal, binary, octal and hexadecimal |
| A domain with accented characters | Punycode converter, showing both the Unicode and the ASCII form |
| A figure to write out in words | Number to words, for cheques and contracts |
Frequently asked questions
Does the CSV converter handle commas inside a field?
Yes. It uses an RFC 4180 parser, so a field wrapped in quotation marks can contain commas, line breaks and escaped quotes without splitting the row. A converter that simply splits on every comma breaks on the first address field it meets, which is the usual failure.
How does JSON to CSV handle nested objects?
It flattens them into dotted column names, so a role object containing a level field becomes a role.level column. Arrays of objects cannot be flattened this way without inventing rows, so the tool reports that case rather than guessing which shape you intended.
Is the text to ASCII codes tool limited to ASCII?
No. The name reflects what people search for, but the tool covers the whole of Unicode. A character outside the first 128 code points, such as an accented letter or an emoji, returns its real code point in decimal, octal, hexadecimal and binary just like any other.
Why does my internationalised domain look like nonsense after conversion?
That is punycode working correctly. DNS carries ASCII only, so a domain with non-Latin characters is encoded into a form beginning xn-- for transport. Browsers convert it back for display. The converter shows both forms so you can see which one a system is storing.