Editor’s note: The following review is part of Macworld’s GemFest 2013. Every day (except Sunday) from mid-July until late September, the Macworld staff will use the Mac Gems blog to briefly cover a standout free or low-cost program. You can view a list of this year’s apps, updated daily, on our handy GemFest page, and you can visit the Mac Gems homepage for past Mac Gems reviews.

If software development or system administration are part of your daily routine, it’s likely that you have deal with complex log files on a regular basis. LogDiver (Mac App Store link) helps you along by offering a way to both parse and filter log entries according to arbitrary sets of rules.

The app comes with a selection of importers for common formats, like the one used by the Apache Web server, or by OS X’s own system log. The filtering capability allows you to extract data based on multiple characteristics, such as a date range or pattern matching on any of the fields stored by your logs.

A convenient and intuitive WYSIWYG interface—somewhat reminiscent of Mail’s rule builder—makes creating even the most complex filter a breeze, and the app’s ability to quickly import and parse extremely large files can help even the most seasoned IT professional get a leg up on a complex problem.

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