There are a couple relevant support articles, but I'll also give you my opinion: * Carefully reviewed: [[Recommended Extensions program]] * All the others: [[Tips for assessing the safety of an extension]] It's like any software you install on your computer or any app you install on your phone: you are placing trust in a combination of the review process and the author's integrity. '''''Review Process.''''' Some add-ons get human eyes on every update before they are made available for download, while others have human eyes only on the first version and then software reviews the updates. Since software can be fooled, automated review cannot assure safety and you need to apply some skepticism, as described in that second article. '''''Author's Integrity.''''' You may know the old New Yorker cartoon: "On the Internet, no one knows you're a dog." It's truly difficult to be sure that an author has their users' best interests at heart. If an add-on is clearly documented, has reviews that look real, and shares its source code, that is better than an add-on with little explanation, fake-sounding reviews, and no links to its source code. You also may want to consider the number of users, but that isn't always a reliable indication. I always think about why an add-on needs the permissions it requests. Sometimes, they are excessive, which is a red flag. But enough theory: if you have a question about a specific add-on, feel free to mention which one it is.