Small developer tools that run in your browser and send nothing anywhere.
JSON Fmt: 2 tools, each with its formula and a worked example.
- Base64 and URL encoderEncode or decode Base64 (UTF-8 safe) and URL-encode or decode text, in the browser, with a note on what each encoding is for.
- JSON formatter and validatorPretty-print, minify or validate JSON in the browser, with the line and column of the first error and an option to sort keys.
About these calculators
JSON Fmt is a set of developer utilities that do one job each: format or validate JSON, encode and decode Base64 and URLs, convert Unix timestamps, hash a string, test a regular expression. Each page loads fast, has no sign-up, and keeps your data on your machine: the code runs in the browser and the page makes no network requests with what you paste.
They are written by a working engineer for the moments when you have a blob of JSON from a log, a token from a header or a timestamp from a database and want to see it properly without installing anything or trusting a random site with the contents.
Every page explains what the tool does under the hood and the edge cases that catch people out, so it is also a short reference.
Who makes this
JSON Fmt is written and kept by ABSU Mobilities, Hyderabad. Every tool page says how it calculates, shows a worked example, and lists its sources with the date they were read. If a number looks wrong, tell us.