I've tried them all (HoudaSpot, DataLore, Spotlight, EasyFind, Find any File, ...) and FoxTrot Professional Search (FTPS) is the best search tool I've found (for my needs, anyway) for these reasons:
1. FTPS does NOT (NOT) rely on just the spotlight index as with the so-called "Spotlight Front-ends". FTPS creates its own indexes. This indexing means that FTPS can find hidden (Files that start with a '.') and files inside a Mac "Package" file (an "APP" in your /Applications Folder or elsewhere). Extremely powerful & Useful.
So, if you need to search for text inside a ".plist" file inside some .app file somewhere, FTPS can find it! You just need to make sure you check that option for FTPS to index invisible files and packages when you set up the index rules (very easy to do, it's just a check box).
Spotlight cannot and does not.
2. FTPS can find files anywhere on your computer.
Spotlight doesn't index everywhere. For example, if you are looking to see where the Java JDK is installed (typically in /Library/Java/JavaVirtualMachines), none of the "Spotlight Front-ends" will find this file for you. Type "jdk1.8" into Spotlight and you get nada.
3. If you need to to use Regular Expressions, FTPS now will support these (in the latest 5.0.2b3). You can also create as many narrowing searches as you need on separate lines. If you don't work with Regular Expressions, well, regularly, you might find a tool like RegExRx useful to help you build regular expressions.
4. Once you have a list of "found files" that match your search request, you can either refine your search or drill down using the excellent tools at the left column.
5. Being able to scroll down and see all the search terms found in, say, matching PDFs in the built-in viewer, is another extremely cool feature. The "Spotlight Front-ends" will find the PDFs (if they're in common locations like your home directory and below, etc.), but they won't let you scroll down and see the search terms highlighted in each document.
Plus, FTPS includes, optionally context in the actual search list so you can see the found terms in that list itself.
You can also highly customize how the display presents your files.
I also found that on one of the Spotlight Front-Ends, that although it did find matching terms in an Excel workbook, I only saw the first sheet displayed. The various sheet links at the bottom didn't do anything when I clicked on them. In FTPS, on the other hand, I could click on the various sheets and see matching terms in any of the sheets. Amazing.
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Regarding other products like DevonThink. FTPS is different in my view.
DevonThink is beyond awesome and I use it all the time for many things, but I think of DT as a repository for all kinds of files for a project or for a client, maybe - but not "system-wide". FTPS, on the other hand, indexes the folders (and only the folders) you tell it to. It will also, optionally, include an index (but not actual file content) of any file anywhere on your computer - say in the system area.
Of course, that's just how I use DT. (DT also creates powerful indexes.)
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So, if you're a home user a spotlight front end may be all you need - or even just spotlight itself for that matter.
However, if you need to be able to find files anywhere almost instantly, including hidden files (like .htaccess for web developers, for example), and possibly files in side apps themselves, then FTPS gives you that power.
And, FTPS is amazingly fast.
Tech support is the only thing about FTPS that seems slow at times, but they do respond, eventually.
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There are a couple of free tools too that give you the ability to search everywhere including invisible files and inside packages. One of these is "EasyFind". EasyFind is a nice tool (from maker's of DevonThink), but it does not create an index. Therefore, while DTPS may seem nearly instantaneous, EasyFind, especially when looking "inside files", could take a long time.
For me, Spotlight is OK for about 70% of my searches. I don't use Spotlight much anymore and just use FTPS.
Finally, I almost didn't find out about FTPS except that on a recent "Mac Power Users" podcast, the guest speaker mentioned it in passing. That got my attention right away since I've been extremely disappointment with Spotlight front-ends simply not finding the files I need.
Cost of FTPS? About $125.
My two cents...
- m