Developer Tools
Common web-development conversions and checks live here: URL and Base64 encoding, HTML entity handling, JSON formatting and validation, and Unix timestamp conversion. These tools link across to related Date & Time and Generator tools, such as the Unix Timestamp Converter linking to the UUID Generator and Date Difference Calculator.
URL Encoder / Decoder
Encode or decode URL component text safely.
B64Base64 Encoder / Decoder
Encode plain text to Base64 or decode Base64 back to text.
{}JSON Formatter & Validator
Validate, pretty-print or minify JSON.
UTCUnix Timestamp Converter
Convert Unix seconds to a date or a local date-time to Unix time.
HTMLHTML Entity Encoder / Decoder
Encode special characters as HTML entities or decode entities back to text.
MDMarkdown to HTML Converter
Convert basic Markdown syntax into HTML markup.
MINHTML Minifier
Remove comments and unnecessary whitespace from HTML.
METAMeta Tag Generator
Generate title, description and viewport meta tags for a web page.
PICKColor Picker
Pick a color visually and get its HEX, RGB and HSL codes.
ROTCaesar Cipher Encoder / Decoder
Encode or decode text with a classic Caesar shift cipher.
What you will find in the Developer Tools category
These utilities handle common web development chores in the browser. For encoding there are the Base64 Encoder / Decoder, the URL Encoder / Decoder and the HTML Entity Encoder / Decoder. For formatting and checking there are the JSON Formatter & Validator, the Markdown to HTML Converter and the HTML Minifier. For page basics there are the Meta Tag Generator, the Color Picker and the Unix Timestamp Converter, and for learning about ciphers there is the Caesar Cipher Encoder / Decoder. Each tool page explains what the operation does, shows a worked example and lists the common mistakes, so the tools are useful for beginners as well as for experienced developers who need a quick check.
Three kinds of encoding and when to use each
Base64, URL encoding and HTML entities are often mixed up, but they solve different problems. Base64 turns bytes into safe text, for example to embed an image in a page or carry binary data in an email. URL encoding, also called percent-encoding, protects characters with special meaning inside a web address, such as spaces, ampersands and question marks. HTML entities protect characters that have special meaning inside markup, such as the less-than sign. Using the wrong one produces broken links, garbled text or security holes. As a rule, encode for the place where the data will be used, and do it exactly once, at the point of output.
Formatting, validating and minifying
The JSON formatter checks that data follows the strict JSON rules and shows it with clear indentation, which makes API responses and configuration files easier to read. Typical errors are single quotes, trailing commas and missing brackets, and the validator points to the position of the first error. The Markdown converter turns simple Markdown into HTML so that you can see how a text will look, and the HTML minifier removes comments and extra whitespace to reduce file size. Always keep the readable original, test the result in a browser and remember that minifying saves only a small share of a page's weight compared with optimising images and scripts.
Page basics: meta tags, colours and timestamps
Good pages need correct basics. The meta tag generator creates a title, a description and a viewport tag, which influence how a page appears in search results and on phones. The colour picker converts a chosen colour into HEX, RGB and HSL values for stylesheets and checks that you have the exact code. The Unix timestamp converter changes the seconds since 1970 into a readable date and back, which helps with logs, tokens and cookies. A 10 digit timestamp is in seconds and a 13 digit one is in milliseconds, so check the length when a date looks wrong. These small tools save many context switches during development.
Encoding is not encryption, and other security notes
Two points deserve emphasis. Base64 is reversible by anyone, so it is not a way to protect a password or a token. And escaping output with HTML entities is one of the main defences against cross-site scripting, in which an attacker gets a script to run in other people's browsers. The Caesar cipher is included as a teaching tool: it shows the idea of a key and a shift, but it can be broken in seconds. For real protection, use proper encryption, a secrets manager and the security features of your framework. Do not paste private keys or live credentials into any website, including tools that run locally.
Typical workflows
A few workflows show how the tools fit together. To debug an API, paste the response into the JSON formatter to find the failing field, then convert any timestamps with the timestamp converter. To publish a page, write the content in Markdown, convert it to HTML, add the meta tags, pick brand colours and minify the final markup. To build a link with a search term, URL-encode the term, and to show user text on a page, escape it with HTML entities. To embed a tiny icon, encode the file with Base64 and use a data address. Each workflow is quick when the right tool is one click away.
Mistakes that cost time
Developers commonly paste JSON with comments, double-encode a value, forget that a space in a query string may be a plus sign, treat a millisecond timestamp as seconds, minify HTML that depends on whitespace between inline elements, or ship a page with a missing viewport tag. Another frequent mistake is to trust a minified or encoded string without decoding it to see what it contains. The tool pages list the checks that catch these, and a good habit is to test the output in the place where it will be used, whether that is a browser, a server or a database.
Tips, privacy and limits
Use these tools for quick checks and learning, and use your build process, test suite and security review for production work. They run inside your browser, so the text you paste is not sent to Dekuz or stored, but you should still avoid pasting secrets. Browser behaviour can differ slightly from your server, so test where the code will run. If a tool gives a result that disagrees with a standard or a library you rely on, tell us on the contact page, and we will investigate and correct it. Suggestions for new developer tools are welcome.
Frequently asked questions about the developer tools
Is Base64 a way to hide data? No, it can be decoded by anyone, so it offers no protection. What is the difference between URL encoding and HTML entities? URL encoding makes a value safe inside a web address, while HTML entities make characters safe inside markup. Why does my JSON fail to parse? Common causes are single quotes, trailing commas, comments and missing brackets, and the validator shows where the first error is. Does minifying HTML change how the page looks? No, it removes only comments and unnecessary whitespace, but you should test the result. Is it safe to paste real keys or passwords? You should not paste live secrets into any website.
A short glossary
Encoding converts data into another form that can be reversed, and encryption protects data with a key. Base64 represents bytes as text. Percent-encoding replaces unsafe characters in addresses with a percent sign and two hexadecimal digits. An HTML entity is a code for a character in markup. JSON is a text format for structured data, and Markdown is a simple syntax for formatted text. Minification removes unneeded characters from code. A meta tag gives information about a page. A Unix timestamp counts the seconds since 1 January 1970 in UTC. A hex colour code writes red, green and blue as hexadecimal pairs.
Getting started: a suggested path
If you are learning, begin with the JSON Formatter & Validator, pasting a small piece of data and then breaking it on purpose to see the error messages. Move on to the encoders: try the URL Encoder / Decoder with a search phrase, the HTML Entity Encoder / Decoder with a line of markup and the Base64 Encoder / Decoder with a short word. Then write a paragraph in Markdown and convert it with the Markdown to HTML Converter, and add tags with the Meta Tag Generator. Use the Unix Timestamp Converter to read dates in logs and the Color Picker for stylesheets. The Caesar Cipher Encoder / Decoder is a fun introduction to cryptography.
Working safely with online developer tools
Treat any website as a place where you should not paste secrets. Use sample data when you test a formatter or an encoder, remove names, tokens and keys from logs before you paste them, and rely on your own environment for anything that touches production systems. The Dekuz tools run in your browser, but an extension, a shared computer or a synced clipboard can still expose what you paste. Keep your own notes about the checks you ran, so that a teammate can repeat them.