Alpus is a dictionary viewer.

Features

• Fast and fully offline operation
• Compatibility with StarDict, DSL, XDXF, Dictd, and TSV/Plain dictionaries
• Compatibility with ZIM files and MediaWiki database dumps
• Typing-friendly search with case, diacritics, and punctuation tolerance
• Fuzzy search
• Full-text search
• In-page popup translator
• History and bookmarks
• Customization options
• Works seamlessly on all your devices

Downloads

1. Free Edition: Fully functional and available for use with up to 5 dictionaries.
2. Universal Purchase: Available on iOS, iPadOS, and macOS as a single purchase.

Examples

Disclaimer: The installable packages provided above are solely for demonstrating the application's essential viewing functionality. The author of the application hereby disclaims any and all liability for the contents of these packages. This includes, but is not limited to, any errors, omissions, or inaccuracies that may be present in the contents.

Compatibility

Alpus is compatible with the following dictionary and file types (main index file extension in parentheses):

• StarDict dictionaries (*.idx)
• DSL dictionaries (*.dsl)
• XDXF dictionaries (*.xdxf)
• Dictd dictionaries (*.index)
• TSV/Plain dictionaries (*.txt, *.dic)
• Hunspell dictionaries (*.aff)
• ZIM files (*.zim)
• MediaWiki dumps (*.xml.bz2)

Setting up dictionaries

• Connect your mobile device to your computer. This step is necessary as all modern mobile operating systems depend on a computer to transfer files to and from apps.
• Transfer the dictionary files to the app's private documents or files folder on your device. For detailed instructions, refer to Android or iOS help documentation.
  (On Android, the typical location of the app's documents folder is: Android/data/com.ngcomputing.fora.android/files)
  (On macOS Catalina or later, use the 'Show' button in the file picker to reveal the app's documents folder in Finder)
• Select the dictionary index file, as listed in the compatibility section above (or an archive of it), using the 'Import Dictionary' option from the 'Manage' menu.
• (Optional) Select multiple index files, with each selection considered and analyzed as one dictionary.
• (Optional) Select resource ZIP files (if available) to copy during the import process.
• (Optional) Edit properties of the dictionary, such as its visible name, using the 'Edit Properties' option in the dictionary menu.
• (Optional) Create a full-text search index for the dictionary using the 'Upgrade' option in the dictionary menu.
• (Optional) Create profiles to group and organize dictionaries.

Resource files

Resource files of a dictionary can be packed in multiple ZIP files with arbitrary sizes and file names. When placed in the root folder of a dictionary (beside the Main.props file), these resource ZIP files 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 supported codec/format. Note that you must keep the filenames and extensions of audio files unchanged after the conversion, as they are hardcoded in article texts.

ZIM files

Importing ZIM files is available only in desktop versions (i.e., "Freeware" versions) and requires, on average, ten times the file size 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 full-text searches of all dictionaries for exact matches. This feature requires a one-time upgrade ("Upgrade All" option in the "Manage" menu) of each dictionary, which may take a considerable amount of time to complete, as every word in the dictionary is indexed for searchability.

Synchronizing between devices

Copying or moving dictionaries between devices can be accomplished using one of the following methods:

• Export the dictionary to an *.aaf file on the first device and then import that *.aaf file on the second device.
• Copy or move the entire "Alpus.Config" folder or individual dictionary folders using a file manager or built-in file operations.
  (After transferring, you may need to add dictionaries to a profile using the "Add to Profile" option in the "Manage" menu.)

Useful tips

• The configuration folder, "Alpus.Config", and individual dictionary folders under the "Dictionaries" folder are portable. You can safely copy or move them between any of your devices. After transferring, you may need to add dictionaries to a profile using the "Add to Profile" option in the "Manage" menu.
• Folder names under the ../Alpus.Config/Dictionaries folder (usually garbled dictionary names) are editable when the app is not running.
• On Android and iOS mobile devices, the "Alpus.Config" folder is automatically deleted when you uninstall the app (whether intentionally or unintentionally). It's highly recommended to back up this folder or individual dictionary folders to avoid the hassle of re-indexing all dictionaries.

Stemming notes

• The app has built-in stemming support for certain languages, namely English, List-1, and List-2).
• For search speed considerations, the app discards deeper stems of a query word when too many stems (root words) are generated by the built-in stemmers.

Search types

There are five types of searches you can perform on dictionaries:

• Regular search: Displays results that exactly match the query.
• Extended matching search: Displays results that match the query with case, diacritics, and punctuation ignored. Suggestions include in-phrase and phonetic matches.
• Full-text search: Provides a list of articles containing exact matches of the query. The search scope includes all text in articles, not limited to headwords, but also definitions, synonyms, examples, etc.
• Fuzzy search: Displays a list of articles most similar to the query. This search acts like a spell checker for words you're uncertain about spelling.
• Wildcard search: Displays a list of articles that match the criteria set by a wildcard query.

Updating

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

Uninstalling

Uninstalling the app consists of removing the Alpus bundle. Some files and folders may need to be removed manually, as described here.

Troubleshooting and FAQ

Q: I bought an offline dictionary, can I use it in Alpus?
A: Probably not. Most standalone dictionaries use their own proprietary data formats, which are 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 matches the query (e.g., occurrences in multi-word phrases) across all dictionaries in the profile when suggestions are activated. Grouping dictionaries into smaller sets based on usage context using profiles may help.

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. You can also use a converter app like PyGlossary to expand the formats available when searching the web for the dictionaries you need.

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

Q: Why is Alpus cheaper on Android than iOS/iPadOS?
A: The cost of both developing for the platform and maintaining an app in the marketplace differs between the two platforms. Therefore, we reflect this difference in the app's pricing.

Fora Dictionary

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

Known limitations

• Slow importing: The app converts every dictionary to its own cross-platform format, which can be a lengthy process. Some large dictionaries may require this conversion to be performed on a powerful desktop computer, and even then, it might take a significant amount of time.
• Limited on-device upgrades: The optimization of the full-text search upgrade is not available on mobile devices due to cross-platform memory management implementation and the intensive nature of the operation. This limitation only affects the setup process and does not impact any usage features on any device.
• No embedded player: The app does not play resource files directly but uses the device's default media player. The default player determines which types of files can be played.

For developers

Technical documentation for integration with other apps or the operating system can be found here.