Editing Tools
Elektrobild
A photo editing site that I most often use for its photocopying filter. Allows you to adjust the filter, customize colors, invert, and more.
3D Gif Maker
Import images and turn them into 3D gifs. Make spinning 2D images, rotating cubes, and more. Allows you to add effects to the image and customize the animation speed, size, etc.
Remove BackgroundThe MOST accurate background removing tool I have found. Allows you to brush areas to erase or restore, and the cutout feature sections elements within the image for you to keep or remove.
Make sure, after you're done with the "cutout" or brush feature, to click the "background" tab again to apply it to the image before saving.
EZ Gif
Import gifs, create your own from videos, choose which frames to remove or keep, crop, resize, and so many more tools for making your perfect gif.
GIMP
Free, open source alternative to Photoshop. GIMP has been widely used and trusted by artists for years. I've used it myself and I have found it reliable. Download is required to run the software.
Imagitool
A standard photo editing tool, no account required. A handful of features are locked behind a paywall, but the essentials are free.