An AI sidebar keeps an assistant next to the page you are reading, so you don't have to copy and paste into a chat window. Well-known options include Sider, Monica, Merlin, HARPA AI and Claudbar.
Browser support. Many tools put Chrome first. If you use Firefox, check that the extension is on Firefox Add-ons.
Privacy. Choose tools that read the page only when you ask and publish a clear privacy policy.
A useful free plan. Summaries and translation should work without a subscription.
Languages. Translation quality matters if you read in more than one language.
Claudbar is free, runs in Firefox and Chrome, supports 30+ languages and has an optional agent mode. It is a good pick if you want a simple sidebar with no paywall up front.
What is the best free AI sidebar?
It depends on your browser and needs. Claudbar is a free option that works in both Firefox and Chrome.