X1 Search is not available for Mac but there are some alternatives that runs on macOS with similar functionality. The best Mac alternative is DocFetcher, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to X1 Search and ten of them are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to X1 Search are Recoll (Free, Open Source), EasyFind (Free), FoxTrot Professional Search (Paid) and HoudahSpot (Paid).
DocFetcher is a portable German/English open source desktop search application. It allows you search the contents of documents on your computer. - You can think of it as Google for your local document repository.
This package is a personal full text search package which is based on a very strong backend (Xapian), for which it provides an easy to use and feature-rich interface. A small fee is required for downloading and using the Windows binary version.
HoudahSpot is an advanced file search tool for Mac. Use HoudahSpot to locate hard-to-find files and keep frequently used files within reach. HoudahSpot builds upon Spotlight, which comes preinstalled with OS X. It makes Spotlight both more powerful and easier to use.
Scherlokk is a lightning fast file search utility build for precise and reliable search of every file which meets the search criteria. Music, pictures, bookmarks, documents, etc can be found quickly and easily.
TextSeek helps you search document contents for Windows and MacOS within seconds, inlcuding PDF, Word, Excel, Powerpoint and other formats. The core feature is that TextSeek can perform search character-by-character with no omission.