I'm not an affiliate for this company or anything, but it's going to sound like it. I feel the need to go on a positive rant. I'll feel better knowing I'm helping other business owners, developers, and agencies add this tool to their toolset.

It helps you fix bugs, but it's much more than that. It's even got a Kanban style tracker for progress. One of my clients is a small air charter company and I developed their website and installed Gleap. I'm using this tool to capture feedback if users have issues but also to survey the audience about locations they want us to service.
The markup tool is amazing and makes it super simple to fix anything and get user feedback.

I was worried it would interfere with our existing chat platform but noticed they have the classic Feedback floating icon that I can customize wherever I want it to show up. The widget is fully customizable.
I was worried this wouldn't work for my agency. I was wrong! Each client has access to their own independent dashboard. You can set up each client as an "Organization" as their own portal and they don't mix with the rest of your clients. This is agency friendly!
The last concern I had was that I might be able to get away with the free version installed on each client's website. As generous as the free plan is, I think an agency is much better off with the paid version, even Tier 4 if possible. You have access to every organization in one simple dashboard and access to all the extra integrations and advanced tools. I can't imagine anyone going all in with these guys and regretting it.
Support rocks too!