I work (as a designer) in an agency where we outsource a lot of front-end web development. A big part of the job is providing feedback and tweaks to developer's builds/HTML (always reasonable, promise).
At the moment I just take screenshots in Safari and mark that up in InDesign, send that as a PDF. It does the job but I'm sure there's a better way both for me and the developer. The comment system in InVision is great, for example. [Juntoo](juntoo.co) looks good, but I haven't heard much of it. Something that can annotate mobile/tablet breakpoints would be amazing.
What do you use? How do you like to provide/receive feedback?