Alpus is a dictionary viewer.



Platform Application Version Requirements License App Store
Windows 11.2 Windows 7 (64-bit) or later Freeware N/A
Mac Alpus-mac-x64.tgz 11.2 OS X Mavericks (10.9) or later Freeware N/A
Linux Alpus-linux-x64.tgz 11.2 amd64 or compatible Freeware N/A
Android Alpus.apk[1] 11.2.4 Android 4.4 or later $6 Alpus on Google Play
iOS N/A 11.2 iOS/iPadOS 9.0 or later $6 Alpus on the App Store
macOS N/A 11.2 macOS Catalina (10.15) or later $6[2] Alpus on the Mac App Store
Updates Change Log
Checksums MD5 or SHA-256

1. Free Edition available for up to 5 dictionaries.
2. Available as an iOS/iPadOS/macOS universal purchase.


No Name Languages Package Source
1. WordNet® English WordNet.aaf
2. Simple Wiktionary English SimpleWiktionary.aaf
3. FOLDOC English FOLDOC.aaf

Disclaimer: The installable packages above are provided for the sole purpose of demonstrating the application's essential viewing functionality. The author of the application hereby rejects any and all liability for the contents of the packages.


Alpus is compatible with the following dictionary/file types:

Setting up dictionaries

Resource files

Resource files of a dictionary can be put into multiple ZIP files with arbitrary sizes and file names. The resource ZIP files placed into the root folder of a dictionary (beside Main.props file) will be detected and indexed automatically.

Troubleshooting: If your device fails to play some audio files in resource ZIP files, you can use a batch converter utility like this app to convert the files to a canonical codec/format your device supports. Note that you must keep the filenames and extensions of audio files unchanged after the conversion since they are hardcoded in article texts.

ZIM files

Importing ZIM files are available only in desktop versions (i.e. "Freeware" versions) and requires on average ten times the size of the file of free hard drive space temporarily during the process. After importing the file using a desktop version on a computer, you can use it in any version of the app on any device.

Full-text search

The app supports searching full-text of all dictionaries for exact matches. The feature requires a one-time upgrading ("Upgrade All" option of the "Manage" menu) of a dictionary which can take a very long time to complete, since every single word anywhere on the dictionary is made searchable during the process.

Synchronizing between devices

Copying/moving dictionaries between devices is done using one of the two available methods:

Useful tips

Stemming notes

Search types

There are five kinds of searches you can perform on dictionaries.


Updating the app consists of keeping the portable "Alpus.Config" folder and replacing the remaining files and folders.


Uninstalling the app consists of removing the Alpus bundle. Some files/folders may need to be removed manually which is described here.

Troubleshooting and FAQ

Q: I bought an offline dictionary, can I use it in Alpus?
A: Probably, no. Most standalone dictionaries have it's own proprietary data format incompatible with general-purpose dictionaries. You need dictionary data in one of the supported formats.

Q: Suggestions are slow when a lot of dictionaries are installed.
A: Unlike traditional search auto-completion, the app performs a complete search and matching of the query (e.g. occurrences in multi-word phrases) on all dictionaries in profile when suggestions are activated. Grouping dictionaries into smaller sets based on usage context using profiles may be helpful.

Q: I can't find the dictionary I need or the dictionary isn't displayed properly when searching.
A: Importing the dictionary using the latest version of the app or using alternate formats may be helpful.

Q: When I modify/replace the Alpus.Config folder manually, my profiles are lost.
A: This is the expected behavior since profiles are stored as app settings (rather than disk files) on mobile devices for the sake of stability.

Q: Why is Alpus cheaper on Android than iOS/iPadOS?
A: Cost of both developing for the platform and maintaining an app in the marketplace is different on the two platforms and hence we reflect the difference in pricing the app.

Fora Dictionary

While supporting similar dictionary formats, Alpus is not data-compatible with Fora Dictionary.

Known limitations

For developers

Integration with other apps or the operating system is briefly described here.