Tech & Media · 16 calculators

Developer Tools

Format and validate JSON, Base64, URL and HTML encoding, regex testing, hashes, UUIDs, timestamps and number bases.

Developer Tool
JSON Formatter
Format, indent or minify JSON, with a structure summary and clear error messages.
JSON.parse then JSON.stringify with your …
Also called json beautifier · json pretty print
JSON Validator Base64 Encoder URL Encoder
Developer Tool
JSON Validator
Check whether JSON is valid and get the exact line and column of the first error.
Parsed with the JSON specification’s own …
Also called validate json · json syntax checker
JSON Formatter Regex Tester Base64 Decoder
Developer Tool
Base64 Encoder
Encode text to Base64 or URL-safe Base64, with the size overhead shown.
Every 3 bytes become 4 characters from th…
Also called encode base64 · text to base64
Base64 Decoder URL Encoder HTML Encoder
Developer Tool
Base64 Decoder
Decode Base64 or URL-safe Base64 back to readable text, with validation.
Every 4 Base64 characters decode back to …
Also called decode base64 · base64 to text
Base64 Encoder URL Decoder JSON Formatter
Developer Tool
URL Encoder
Percent-encode text for use in a URL path, query string or form body.
Unsafe bytes become %XX in hexadecimal
Also called percent encode · encode url
URL Decoder Base64 Encoder HTML Encoder
Developer Tool
URL Decoder
Decode percent-encoded URLs back to readable text, and split a query string into parameters.
%XX sequences are converted back to their…
Also called percent decode · decode url
URL Encoder Base64 Decoder JSON Formatter
Developer Tool
HTML Encoder
Escape HTML special characters so text displays literally instead of being parsed as markup.
& < > " and ' become their named or numer…
Also called html escape · encode html entities
HTML Decoder URL Encoder Base64 Encoder
Developer Tool
HTML Decoder
Convert HTML entities back to the characters they represent, including numeric ones.
&name; and &#number; are replaced by the …
Also called html unescape · decode html entities
HTML Encoder URL Decoder Regex Tester
Developer Tool
Regex Tester
Test a regular expression against sample text and see every match and capture group.
Your pattern is compiled with the flags c…
Also called regular expression tester · regex match tester
JSON Validator HTML Encoder Hash Generator
Developer Tool
Hash Generator
Generate SHA-256, SHA-1 and CRC-32 hashes of any text, entirely in your browser.
SHA-256 as specified in FIPS 180-4
Also called sha256 generator · checksum calculator
UUID Generator Base64 Encoder JSON Formatter
Developer Tool
UUID Generator
Generate version 4 format UUIDs from a seed, so the same seed always gives the same IDs.
SHA-256 of the seed, reformatted into the…
Also called guid generator · uuid v4
Hash Generator Base64 Encoder Unix Timestamp Converter
Developer Tool
Unix Timestamp Converter
Convert between Unix timestamps and human-readable dates, in seconds or milliseconds.
timestamp = milliseconds since 1970-01-01…
Also called epoch converter · timestamp to date
Time Zone Converter Date Difference UUID Generator
Developer Tool
Binary Converter
Convert binary to decimal, hexadecimal and octal, and back again, with bit information.
Each binary digit is a power of 2, read f…
Also called binary to decimal · decimal to binary
Hex Converter Decimal Converter Octal Converter
Developer Tool
Decimal Converter
Convert a decimal number to binary, hexadecimal, octal or any base from 2 to 36.
Repeatedly divide by the target base and …
Also called decimal to binary · decimal to hex
Binary Converter Hex Converter Octal Converter
Developer Tool
Hex Converter
Convert hexadecimal to decimal, binary and octal, with the byte breakdown.
Each hex digit represents exactly 4 bits
Also called hex to decimal · decimal to hex
Binary Converter Decimal Converter RGB to HEX Converter
Developer Tool
Octal Converter
Convert octal to decimal, binary and hexadecimal — useful for Unix file permissions.
Each octal digit represents exactly 3 bits
Also called octal to decimal · decimal to octal
Binary Converter Hex Converter Decimal Converter

Key developer tool formulas

JSON Formatter	JSON.parse then JSON.stringify with your chosen indentation
JSON Validator	Parsed with the JSON specification’s own rules
Base64 Encoder	Every 3 bytes become 4 characters from the 64-character alphabet
Base64 Decoder	Every 4 Base64 characters decode back to 3 bytes
URL Encoder	Unsafe bytes become %XX in hexadecimal
URL Decoder	%XX sequences are converted back to their bytes and read as UTF-8
HTML Encoder	& < > " and ' become their named or numeric entities
HTML Decoder	&name; and &#number; are replaced by the characters they stand for
Regex Tester	Your pattern is compiled with the flags chosen and run against the text
Hash Generator	SHA-256 as specified in FIPS 180-4

Developer Tool questions

Is my JSON sent to a server?

No. The formatting runs entirely in your browser, so you can safely paste configuration or API responses.

Is Base64 encryption?

No. It is an encoding, not a cipher — anyone can decode it instantly. Never use it to protect secrets.

Why is a nested quantifier rejected?

Patterns such as (a+)+ can take exponential time on some inputs and lock up the page. Rewrite them with a single quantifier.

Is my text sent anywhere?

No — the hash is computed in your browser with a pure JavaScript implementation.

What is the year 2038 problem?

A signed 32-bit timestamp overflows on 19 January 2038. Modern systems use 64-bit values and are unaffected.