Here's a short listicle about online art resources and programs that I enjoy using for my work. These tools work for me, but please browse with discretion!
Medibang Paint is my favorite drawing application of all time. I find it easy to use, unlike apps like Photoshop and Clip Studio. Though these latter applications are clearly more feature-rich than Medibang, they are also costly, requiring a regular subscription fee, and suffer from (what I personally view as) a bloat of features that obscures the more basic tools for illustration. To the contrary, I find that Medibang is just as complex as it needs to be and no more, making the user experience fresh and easy. I'm also biased, because I've been using it as my main art program for a decade now. Medibang also has some limited free cloud storage if you sign in with a free account. Unfortunately, I think the iOS app functionality is poor.
I think that the best feature of Medibang is the simple, intuitive comic tools. Medibang makes panel creation and layout extremely easy. A downside, however, is that lettering is difficult, as there are no good tools for creating text bubbles (I hand-draw them) and a god awful text tool.
FireAlpaca is a Medibang alternative - the former is basically identical to the latter. I used this for a number of years before I switched to Medibang. There is no iOS version and no cloud features or comic making features, last as I remember. However, there are some very rudimentary animation features.
This commandline tool takes a little bit of understanding of computer commands (or a willingness to search for stack overflow answers!) to understand, but is very yielding. Some simple commands can be used to resize and edit batches of images at once, which has saved my ass many times over when trying to compile and edit comic pages to convert them from digital to print. I might write a mini blog post about how I use ImageMagick later.
I use Medibang to draw and letter my comics, and while I love the app to death, it just does not have a very good text tool. I use this tool to generate line breaks for me to make my text look better, since I can't just resize a text box to do it. Easy to use and usually gives pretty good results!
This is a simple web-based tool that helps you draw text art based on these full width "halftone"-like block symbols. Not technically ASCII, though.
Bulk Rename Utility in absolute lifesaver for managing and renaming large amounts of comic pages. Rename, renumber, prefix, suffix, and reorganize multiple files quickly.
Bulk Resize Photos is a web-based app which can be used to quickly resize batches of photos (or comic pages), but is pretty speedy since it doesn't require any uploading or downloading (it somehow works in the browser). I no longer use this service since I learned how to use ImageMagick, which I've detailed below.
A simple web-based image editor that applies pixel dithering filters on images. The presets are cool enough, but you can mess with the settings and get some really cool results!
A web-based tool to create interesting image effects that I use to "retro-ify" my images. You can get some basic animations out of this, especially glitchy VHS-y effects in looping GIF form.