Userscripts:

• Duolingo All Scripts
  • Like Duolingo Mods, except auto-updating. It loads the newest version of Duolingo Mods from github.com, so that you never have to update again.
• Duolingo Mods (all scripts)
  • Loads all the below scripts, plus will become a place for me to put smaller mods. If you don't want all the scripts, you can disable whichever you like from the Duolingo Settings page. (Neat, huh?)
• Duolingo Lesson Review
  • Allows you to go back and review problems during lessons
  • NOTE: This userscript no longer works due to changes by Duolingo. I have not been able to maintain it of late. Installing it will probably do nothing.
• Duolingo Easy Accents
  • Type special characters just by using alt. No need for alt codes, new keyboard layouts, or clicking
  • This one still works, as of June 2016
• Duolingo Comment Links
  • Turns the timestamp into a direct link for every comment in Duolingo's Dicussions
  • NOTE: This userscript no longer works due to changes by Duolingo.

Installation instructions

Chrome

1. Install the browser extension Tampermonkey
2. Left click on the script you want above
3. Click Install
4. Reload the Stack Exchange page, if necessary

Firefox

1. Install Greasemonkey and restart Firefox
2. Left click (regular click) on the script you want above
3. Click "Install"
4. If necessary, reload the page you want the script to work on.

Internet Explorer

1. Get a browser
2. Follow the instructions for that browser