Adobe XD is a free software for making User Interfaces, this is quite good for developers who don’t want to spend much on their tools, but make quality designs.
Adobe Illustrator is an extension of making symbols and logos etc for Adobe XD, but this is more advanced and has a subscription payment.
Affinity Designer is what you’ll go for if you’re a die hard UI designer, it has the tools, features and is much easier to use than Adobe XD, though this what you call “You get what you pay for”. I believe in most workplaces, they use this application? a friend told me, so yeah.
There are probably more programs out there(Photoshop, Indesign, Sketch etc.) , but these are the common-ish ones… I also made this guide on how to create nice UI designs, so you might wanna check this out: