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Fiddlers: Free online tools you can experiment with

This page is part of the “Cheatsheet of Epicness: JD’s incomplete collection”, continue the read at your own risk.

Sometimes you face tricky decisions you need to make before implementing a solution. In these situations, you need to have a spike in order to figure if an option can become part of that solution. Spikes take time, whether they concern technology stacks to pick or similar functions within a framework. Luckily for us, more and more benevolent souls implement fiddlers that allow reproducing scenarios we want to test. Other times you are trying to check that formatting you worked on for hours is correct. Rejoice, for that now you can. These tools are a great help because they save you time and a potential headache setting up stuff you might never need. This is a list of fiddlers I find useful.

SQL fiddlers

db fiddle one of my favourite fiddlers
dbfiddle in action 
  • dbfiddle: This is a simple but effective tool allowing you to test a great variety of scenarios. It supports the latest versions Oracle, MySQL, MariaDB, SQLServer and so on. 

Formatting fiddlers

Regular expressions

Regular expressions, very often we think we understand them. Wrote them once in a Java program, should work the same in JavaScript or PHP. Right? Well, absolutely not! As you may imagine, I went through a great deal of pain learning this again and again. From a language to the next. All these subtleties you can never remember even if you actually endured them before. The suffering is real. Today I say it. No more! Today you get the gift of Regex101. Indeed, it allows you to test your regular expressions against a whole bunch of languages and gives you details about how and why your regex is (not) working. Also, it provides you with references to help you improve your pattern matching. Just enjoy.

Regex101: One of my favourite fiddlers
Regex101 everyone!


  • JSON formatter: This one is pretty straightforward, you put the alleged JSON in the input and in an instant you know what’s up.
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