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Updated
Xojo is a cross-platform development tool that allows you to easily build native apps for Windows, macOS, Linux, Raspberry Pi, iOS and the web.
SpecsUpdate
Pros
Pro Very easy to learn, cross-platform compilation often requires just a click
More advanced features are doable with declared, great third-party plugins (Monkeybread & Einhugur are highly recommended), not a subscription.
On the downside bugs can linger for years, some features not as complete or powerful as they should be, some expected features (eg calendar control) not there as community or third party provide solutions (so no need to implement and no wish to compete).
Pro Nice to have back end code that can be shared for Web apps as well as Desktop apps
Pro Free to try, you pay only when you compile for a platform
You pay for one year of updates, then your license still works but you don't get more updates.
Pro Running a debug instance of your app on Windows while the IDE is on Mac is a great way of working.
You can have the Xojo IDE running on macOS with a target build of your app running on a Windows computer, the two computers networked to each other. This lets you build on the Mac launch the app on Windows, then watch the code execute from the Mac, pausing to inspect or modify variables, without interfering with the IDE on the Windows computer. No lost or confused events that can happen when you interrupt a running app to do this.
Cons
Con Subscription-based/Not free
Using this product you're betting the company will still be around. If they get bought out by an enterprise that wants to use the tech internally, all they need to do is stop offering subscriptions and suddenly you're scrambling to rebuild your entire app on other technology.
Con Targets not always 100% percent compliant with platform standards
What this means is that to get a perfect match for MacOS or Windows or Linux you will have to get into Declares or use 3rd party plugins to get them looking identical to what you'd get with the default platform IDE's (i.e. xCode for MacOS, Visual Studio for Windows). Xojo does the lowest common denominator for controls so it's a bit more work to make each target look perfect (or as perfect as possible).