Two sites (and one app) to figure out file extensions

I had previously covered TrID, using which is one of the very few ways to figure out what is inside file without extension.

However if extension is known then it is much easier to figure out what to do with file. There are plenty of ways to do that. I picked FILExt and OpenWith to compare.


filext_icon Old established site with database on file extensions. Usually suggests at least few variants of what file may be and sometimes adds in-depth information such as mime-type and associated software.

Site design may seem bit outdated and cluttered but believe me – it’s good at what it does.

Link filext.com


openwith_icon Seems to be newcomer site (I first saw mentions last month when it was covered on Performancing and gHacks). In addition to pure theory service is eager to offer links to free software to open specific file types.

There is also desktop tool provided that integrates into Windows context menu. I think it is bit excessive and it also has optional shareware bundled.

Link openwith.org

Head to head

I had perfect test case today while cleaning C++ projects in my Dropbox and wondering what NCB files are. FILExt offered three versions including fitting one (IntelliSense data) but OpenWith failed to come up with any.

OpenWith looks closer to Web2.0 age but FILExt seems to have edge in database volume and quality.

Which one to use

FILExt with its extensive database is clearly only stop needed for techies. However OpenWith is more polished and focused on offering good free software to handle those files. May be better for novice users, that are unlikely to encounter obscure file types anyway.

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  • Jeannie #

    trid is also excellent for file info
  • Rarst #

    @Jeannie Yeah, but trid is bit too advanced for most users and mostly helpful when file is lacking extension. :) Quick lookup online is often enough.
  • File-Extensions.org – file extensions and types catalogue | Rarst.net #

    [...] back Petr Novotny had contacted me about his site as possible addition to my post on file extension databases. I rarely re-write past posts, unless there is need for considerable [...]