Many browser extensions are free to use, but some may require a paid subscription or a one-time purchase. Some extensions offer a free version with limited features, and a paid version with additional features or support. Additionally, some browser extensions may be open-source and free to use, but the developer may request donations.
It is important to check the pricing and the terms of use before installing a browser extension, and to be aware of any recurring charges or subscription fees associated with the extension.Also, be aware of the "free" extensions that may have hidden costs, such as showing ads, or collecting and selling your data. It is always good to read reviews and check the privacy policy of the extension before installing it.