Is it possible to search an apt repository via a web browser?

Solution 1:

packages.ubuntu.com allows you to browse and search all the packages that are available in each Ubuntu release.

You can also look at the packages file of an apt repository. For example http://old-releases.ubuntu.com/ubuntu/dists/lucid/main/binary-amd64/Packages.gz and http://archive.ubuntu.com/ubuntu/dists/focal/main/binary-amd64/Packages.gz are the lists of packages in the Ubuntu 10.04 Lucid and 20.04 Focal main distributions for amd64 processors. Browse the directory trees to see the other available distributions. You'll find the referenced packages for all currently supported releases under http://archive.ubuntu.com/ubuntu/pool/ and previous releases under http://old-releases.ubuntu.com/ubuntu/pool/.

Solution 2:

Yes. packages.ubuntu.com