A so-called "host-based application firewall" for your Mac. Basically, it monitors all your applications and informs you when they try to connect to the internet. It is then up to you to allow this or instrcut Little Snitch to prevent it. The software also can show you the applications' connections graphically on a map. There is a trial version available. Install it. You will be surprised to see all the connection your applications make.
Alledgedly the world's number one imaging software from PhaseOne. It supports more than 400 cameras and thousands of lenses. The strength of Capture One is the its raw processing capability. While a matter of taste, Capture One's raw processor produces "better" rsults than other raw processing engines, such as Adobe's Lightroom. Pity the latest release (22), which introduced features such as HDR and panorama stitching, does not support my 2011 iMac, which only runs macOS 10.13 (High Sierra). Perhaps it is now the right to get a new toy...
A full-fledged Photoshop replacement for Mac, iPad and Windows - with everything you need and probably a bit more in most cases including layers and non-destructive editing (for most of the functions). Contrary to Photoshop, this is not a cloud service, so you pay once and own the software.
Affinity is also great to replace backgrounds. In case you are looking for respective new backgrounds, have a look at Pexels.
TurboCollage - as the name indicates - can produce different sorts of collages from a given set of images. The dimensions of the final collage can bis specified by the user and the largest I have done so far was 178x118cm, resulting in a 700 MB JPEG.
Ever had a large collection of images you needed to convert into a different format, resize, watermark or alike? XnConvert is a freeware program that can do all of that for you.
While on a short trip, I reviewed my Canon's images on my iPhone and deleted the best images by accident. There are quite a few un-delete programs available on the market, most of them are to be paid for. PhotoRec is free and it works...
Sometimes you have a bunch of files, e.g. exported from one of your applications, and the names of the files are just not right. NameChanger renames a batch of files quickly and easily.
A audio converter for Mac an Windows that converts about every common format to another. If you need to change tags, especially ID3, use Kid3. If you want to covert your MP3s into Apple-compatible audiobooks (m4b), try Audio Book Binder, which provides you with a nice GUI as well as a command line interface.
An easy to use (while still feature-rich) database systems that allows you to build applications on either a Mac or a Windows system. The resulting applications run without modifications on Mac and Windows and (with some limitations) on an iPad/iPhone. Applications I have implemented so far include Risk Assessments (amongst otehr things you can prepare and document risk assessments, produce PDF reports and track remediation activities) and Team Tracking.
In case you like listening to audio books, have a look at Audiobook Buider, which allows you to, well, convert MP3 into M4B audiobook format, which is used by iPods, iPads and iPhone - and many other devices including Android phones. M4Bs are convenient as they are typically smaller than the MP3 (I am typically converting mono audio books into 80 kBit/sec and stereo into 96 kBit/sec M4Bs) and teh devices playing them typically remember the last position played.
Alternatively, have a look at Audiobook Binder, which is free. It also has a handy command line interface, around which I have written an neat PHP program that can convert multiples audio books in one go, including appropriate tagging, album art and chapter marks (chapter marks allow you to jump from one chapter to another, typically these are the individual files you are compiling the audio book from).