TextLength is a simple tool to estimate translation lengths.
The most common internationalization problem is not having enough space for translations.
If your design includes words, make sure you have enough space to fit longer translations. If you don’t, you might end up with overlapping text or text that gets cut off.
Here, you can easily compare length of a button text, a description you've put in a fixed width column ... between different languages and then find the appropriate width you need to keep in mind for your next design.