A French duo got frustrated with QA testing for mobile apps, so they spent a month coding and designing a new service called Duologue. Duologue helps you compare app screenshots with mockups, track bugs and comment.

“These days, I’ve been developing a few mobile apps,” developer Paul Dupuy told me. “The process to test and report UX bugs really got on my nerves.”

Here’s the result, a neat little tool that he just launched today with designer Oskari Grönroos. It’s a paid service that will cost you $49 per month for an unlimited number of projects and 10 users.

I can see companies working with freelance app developers using this kind of tool. It’s very straightforward and could help you save a bit of time — annotation tools like Skitch, Droplr or Bugshot aren’t as powerful as Duologue.

The team already showed Duologue to a few people, and nearly all of them are still actively using it and are enthusiastic. It’s a niche tool, but it’s a small project as well that was developed by a small team. Duologue could find a small app developer audience with this kind of services.