In my teaching I use as many free web-based apps as possible. Why? They're free. They make great alternatives to expensive software. I don't have to pay for upgrades every few years. There is no installation necessary. Etc.
An excellent alternative to Adobe Illustrator and CorelDraw is YouiDraw. It offers a drawing app, a logo creator and a painting app in which you can easily create cool shading in your drawings.
The free plan gives you plenty of tools and options. YouiDraw syncs with Google Drive, Dropbox, and OneDrive. The learning curve for the drawing app is a little high, but hey, it's a vector drawing tool! A user manual is available. In the free version, drawings can be exported as png or jpeg.
Most logo creators I've seen are very limited, offering only pre-made templates in which the designer enters text and changes colors. YouiDraw offers much more freedom of creativity. While it does have templates, you can also start with a blank screen. Not only can you create graphics, but you can import them as well. A user manual is available. In the free version, logos can be exported as png or jpeg files.
I love the way I can shade objects with the pen tool in the painting app. My hand-drawing skills are average at best, but I can scan a line drawing and insert it into YouiDraw to touch it up and give it a more professional look! Options for the pen tool are plain, sketchy, shaded, web, trail, ribbon and fur. I can also color a line drawing with the brush tool. Shapes can also be filled with a solid color, gradient, or pattern. A user manual is available. Paintings can be saved only as png files.
YouiDraw definitely needs improved selection tools. The only tool available is a rectangle, making it difficult, if not impossible, to select a circle or other curved objects. In addition, layers would make painting much easier. A tool like Illustrator's pathfinder would be icing on the cake!
As of this writing I have only used a mouse for drawing. I will need to connect my pen tablet to see if it will function properly with YouiDraw. I also want to try the app on a Chromebook. Needless to say, I love this app. I am not an artist by any means, but YouiDraw helps my scanned drawings look much more professional! It is less frustrating than trying to learn Illustrator or CorelDraw, but it also lacks some important features.