Mac Application to defrag my Mac drive

Speed of access on HFS+ drives is not that affected by fragmentation unlike Windows file systems as OSX will do some defragmentation. A third party investigation is here.

You might be better off checking there is enough free space for new files.

There are some utilities to do defragmentation like iDefrag

On APFS - you don’t need to defragment anything. On HFS+ - DriveGenius does what you ask. It rebuilds the catalog (filesystem) that tracks the files. You don’t need to rearrange the files on the drive as macOS does that for you - just keep 20 GB free or 25% free if you can, and the system optimizes the file location automatically.

There aren't many apps that do this on mac since actual filesystem fragmentation both rare and rarely a cause of measurable slowdown.

Mac OS X automatically defragments files that are likely to cause a slowdown in addition to automatically optimizing hot (often used) files to a fast and not-fragmented part of the drive.

The HFS+ filesystem directory / catalog itself can become fragmented over a long time but you can fix that easily. Back up to time machine and an erase install / migration back cures that issue without needing to spend money on a live tool. DiskWarrior also helps to rebuild HFS+ catalogs in addition to the already mentioned Drive Genius.

Best of luck - keep looking if you find defrag isn't what the doctor ordered on your mac.