Some of my favorite browser extensions require access to “Your data on all websites” or “All data on your computer and the websites you visit”. Technically this means that I grant the developers of such extensions full access to my entire communication with all websites I visit, including login sessions (cookies, password, etc.), private data (docs, e-mails, photos, etc.) even online banking credentials or credit card info – and for some single extensions even worse – to all data on my computers.
Even Google warns not to grant these rights to third parties:
In the future I will only trust extension authorities, which can access my data on their own domains anyway (like Gmail extension for mail.google.com) or install a few necessary extensions only.
Here’s my trusted list for secure and useful browser extensions.