Privacy, security & networkingCharles has been the answer to "what is this app actually sending?" for about twenty years. You run it, point your Mac or a phone on the same Wi-Fi at it, and every request appears in a tree you can expand: headers, bodies, timings, cookies. From there you can throttle the connection to something dial-up slow, swap a response for a local file, or hold a request at a breakpoint and edit it before it goes out. It is as useful for auditing a suspicious app's phone-home traffic as it is for debugging your own API.
The licence is unusually plain about its limits. Fifty dollars buys the current major version and every update within it. When version 6 arrives, that is 40% of what you paid, or free if you bought within three months of the release. Knowing the number in advance is worth something.
Two things to weigh. It is Java, so the window looks out of place and feels heavier than Proxyman, which is the native alternative many people now prefer. And if you inspect traffic once a year, the free 30-minute sessions genuinely cover it, so there is no hurry to buy.
Little Snitch
Secrets
1Blocker
Radio Silence