When working with regular expressions I've always found them tough to read when single line formatted. Debugging is also time consuming trying to look for syntax errors.

RegExd auto-formats single line regular expressions into multiple lines with indentation to make it easier to drill down into each part. If an expression doesn't compile, it searches for the longest valid sub-expression and highlights the error.

There's also a few other features, but I'll leave those to be discovered.

Feedback is appreciated!