Cloakshot by Spawn Lau is a screenshot redaction app for iPhone, iPad, and Android (works on Mac just fine). Scan and edit on your device; export with an eligible trial or one-time Pro purchase.
I use CleanShot X for most of my redaction work, but the automatic scanning and simplified redaction in Cloakshot works really well and could be a real timesaver if you share a lot of images that need redaction.
