I'll be honest, once I decided I needed a solution, and that browser extensions weren't an option, I didn't really try that hard to find a bookmark alternative as I figured I could create something to do the job fairly quickly.

The first version of FormFiller was written in about 30 minutes over the course of 2 lunch breaks and it did what I needed it to (though not very elegantly. It send the generated JS bookmark code to a php script which saved it to a file which was then loaded in the created bookmarklet. Caused issues with https though :( )

Also, because I originally made it for use at my day job, there were some special use cases that I hard coded in.

Once I'd got to that point, the thought of looking for existing solutions didn't cross my mind.

Now, to answer your question, having looked at the project you linked, I would say that there are only a few differences (at the moment).

1) While they are both open source, FormFiller is on GitHub and therefore I feel it's a bit easier for people to access the source code and potentially contribute.

2) The FormFiller save bookmarklet loads the code from https://rawgit.com/wearecontrast/FormFiller/master/src/FormF.... What this means is that when I update FormFiller with new features, everyone gets upgraded without having to create a new Save bookmarklet. (This doesn't update the generated bookmarklets though. Anyone wanted to take advantage of a new feature can just use their current bookmarklet to populate the form, then save again using the automatically updated Save bookmarklet. The benefit of this is, if your generated bookmarklet works now, it will always work regardless of any features added/removed in the future)

3) When you click the FormFiller bookmark to save a form, you are presented with a modal window. Currently, the only thing you can do on this window is change the name of the link (and thus the name of your bookmark). The plan going forward is to re-implement some of the functionality I need at work. This means being able to select certain fields to have random values inserted, and also having fields have calculated values inserted. for example, random characters in the name fields, and always inserting the current date (or +3 days) into a date field.

4) The only other difference I could see was that FormFiller does not split up the generated bookmarklets for multiple forms on the page. I'm not sure if this is better or worse though?

Thanks for the comment and I hope that gives a bit of insight into where I'm planning on taking FormFiller. If you end up giving FormFiller a try then feedback is always appreciated :D

Cheers, Mike