Mozilla Firefox has a few tools that enable users to search for patent and patent applications, using the search bar that is present in the top right corner of the window (a screenshot is shown below for reference and the search field is circled in blue).
Currently, users may search for patents issued in the US and published patent applications in the USPTO (A and B respectively). On selecting one of the options, the user may enter a patent or patent application number and the target patent/patent application is displayed in the USPTO website.
Users may also search on Google Patents directly from the search bar (by selecting C).
The links to the above mentioned search tools are as follows:
There are other tools that may help users to search for patents, the above listed are just the tools that I find useful. One can explore more search tools using the manage search engine option (D).