Writing code always comes with a stream of small, nagging tasks: formatting a blob of JSON, testing a regex pattern, encoding a string. Rather than hacking together a few lines in the console just to check something, it's often faster to reach for a ready-made online tool and get your answer in seconds. Here's a collection of free tools that come in handy during development.
When debugging an API, you'll often be staring at a response crammed onto a single line. Formatting it makes the structure immediately clear, and the tool can also compress it back down to one line and flag syntax errors along the way.
The worst part of writing a regular expression is the endless cycle of tweak-and-retest. This tool lets you type in your pattern and test string and see every match update live — much faster than sprinkling debug logs through your code.
When a parameter contains Chinese characters or special symbols that need encoding, use the encoder/decoder tool; when you want to break down a long URL to see exactly what parameters it's carrying, the URL parser lists them out field by field.
You'll frequently need to manually encode or decode a chunk of Base64 data while debugging an API — for instance, checking whether the Base64 image content returned by an endpoint actually looks right.
Useful for file verification, simple deduplication, or generating a unique identifier — just enter your text and get the corresponding MD5 hash instantly, computed entirely on the front end without the content ever leaving your browser.
Digging through logs often means converting a timestamp into a readable date, or going the other way to pass a timestamp as a parameter — this tool converts both directions, at the second or millisecond level.
A design file gives you a hex color, but your code needs HSL so you can easily adjust lightness — this tool converts freely between HEX, RGB, and HSL.
Every one of these tools runs entirely on the front end, so none of your data is ever uploaded to a server — safe to use even when debugging data from internal systems.