Free Developer Tools – JSON, Regex, UUID, Base64 & Hash
Small utilities for the moments in the middle of real work: reading a minified API response, working out why a regex matches too much, generating test IDs, decoding a token, or checking a download against its published checksum. Everything runs in your browser, so pasted payloads, tokens and files are not sent to a server.
JSON Formatter
Format, minify and validate JSON. Upload a .json file or paste text; invalid JSON shows the parser's error with the line and column where it stopped.
JSON to CSV Converter
Convert a JSON array of objects to CSV. Nested fields become dot-notation columns, missing keys become empty cells, and you choose which columns to export.
Text Encoder & Decoder
Decode a JWT's header and payload, or encode and decode Base64, URL and HTML entities in your browser. ROT13, Caesar shifts and SHA-1 or SHA-256 are included too.
Animated Button Generator
Design a CSS button with 8 presets and 9 motion effects, then copy it as plain HTML + CSS, CSS Modules, styled-components or Tailwind code.
HTML CSS JavaScript Live Preview
Write HTML, CSS and JavaScript in separate editor tabs and see the result update live in a sandboxed preview, with full, tablet and mobile widths.
UUID Generator
Generate random version 4 UUIDs (GUIDs) in bulk, up to 100 at a time. Choose uppercase, no hyphens or braces, and copy one value, all of them, or a JSON array.
Regex Tester
Test JavaScript regular expressions against your own text. Every match is highlighted, with its index and capture groups listed below.
Number System Converter
Convert between hexadecimal, decimal, binary and octal. Type in any field and the other three update; works for non-negative whole numbers of any size.
Image to Base64 Converter
Convert an image to a Base64 string or data URI, or paste Base64 to preview the image and download it. Handles PNG, JPG, GIF, WebP and SVG; nothing is uploaded.
Hash Generator
Compute MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes of text or a file at once, and compare them with a published checksum.
How to use these tools
Select the tool that matches your task, open it, and follow the steps below.
- Pick the tool for the data you have: JSON, a token or encoded string, a number, an image, or a snippet of front-end code.
- Paste your input. The JSON tools and Image to Base64 also take files, and the Hash Generator can hash a file.
- Copy or download the result and carry on with what you were doing.
Common ways to use these tools
- Format and validate an API response, and see the line and column where invalid JSON breaks.
- Convert a JSON array of records to CSV for a spreadsheet.
- Decode a JWT's claims, or encode and decode Base64, URL and HTML entities.
- Generate UUIDs for test data, or MD5, SHA-1, SHA-256 and SHA-512 hashes of text or a file.
- Test a regular expression, convert between hex, decimal, binary and octal, or preview HTML, CSS and JavaScript as you write it.
Which Developer Tool Do I Need?
Pick by the data you have in front of you:
- A JSON response or config file: read it, check it and minify it in the JSON Formatter, or turn an array of records into a spreadsheet with the JSON to CSV Converter.
- A token, header or encoded string: the Text Encoder & Decoder decodes JWTs and handles Base64, URL and HTML encoding. For images, Image to Base64 converts in both directions.
- A pattern or a number: test a regular expression in the Regex Tester, or convert hex, decimal, binary and octal with the Number System Converter.
- An identifier or a checksum: generate IDs with the UUID Generator, and hash text or a file with the Hash Generator.
- Front-end code: build a button with the Animated Button Generator, then try it out in the HTML CSS JavaScript Live Preview.
For a walkthrough, see our guide to formatting and validating JSON.
Your input stays in your browser
These tools process what you paste or choose inside your browser, so JSON payloads, tokens and files are not uploaded to a server.