Is Adobe Photoshop CS5 compatible with macOS High Sierra?

There are some incompatibilities, and I personally would not update if I were in your situation. PS 5.5 works, but will always crash if you use the File Info. (A good way to lose all your work up to that point - save you're work often!). So far, it seems to work otherwise, although when I quit the program, it closes down very quickly and about a minute latter a notice comes up that PS shut down unexpectedly. It did freeze the computer once. Also, if you quit the program, it will not ask you if you wish to save the changes.

Aperture also seems to have some issues for me with crashes when exporting originals with IPTC (but not versions, or originals without the IPTC added), or when trying to "Write IPTC to Originals". Good to know if this will affect your work flow with your photos.

See this site to check for compatibility:

http://roaringapps.com/

CS5 is most likely a 32-bit app. I've seen complaints for 32-bit apps in High Sierra.

Apple announced at WWDC that the company will start to phase out support for 32-bit software in macOS. In January 2018 new apps submitted by developers to the App Store must be 64-bit apps. Also, all apps and app updates must be 64-bit by June 2018. Eventually, 32-bit support will no longer exist in macOS, probably in a version after High Sierra.

How to find 32-bit apps installed on your Mac

http://www.needhelp4mac.com/2017/07/how-to-find-32-bit-apps-installed-on-your-ma c/

(Fair disclosure: Needhelp4Mac is my site. I may receive some form of compensation, financial or otherwise, from links on my site.)

For one, the app is not "in the cloud", it is installed on

your machine like any other version was. It only needs

to periodically check with the Adobe servers to see if

it is still a valid license. I know that you can go for periods

of time with no internet connectivity at all without issue.

It will attempt to validate every 30 days.

There are also some current alternatives that are quite equal to

that 6-7 year old software, and cheaper.

FWIW, $10 month is not a bad deal for both Photoshop

and Lightroom considering old retail costs of both would

be in the upwards of $500+.

jurkuipers wrote:

....

You're right - there are good alternatives to CS5, - "Affinity Photo" looks like a good alternative to me.

...And a lot cheeper...

....

And also supports a good many Photoshop plugins.