• Photopea: The most advanced online Photoshop site. Takes a bit of time to figure out, but it can do everything Adobe Photoshop can, including editing animated gifs as well as saving edits to Imgur. - https://www.photopea.com/

• Ez Gif: Online video to animated gif converter and editor. I recommend using Photopea to edit gifs as it's more advanced and has better quality, but this is a great site to use regardless. - https://ezgif.com/

• Photo Mania: Filter and editing site. - https://photomania.net/

• Pixlr: Filter and editing site. - https://pixlr.com/

• Lunapic: The old trusty photo filter and editing site since Myspace. It's outdated today but people still like to use it. - https://www5.lunapic.com/editor/