Best 7 Open-Source Offline Dictionary Apps for Android

The English Wiktionary now holds 10,105,827 entries, all released under a free license and free to redistribute. That is more raw dictionary data than a single phone could ever need, yet almost none of it reaches Android users without a login screen, a subscription, or a live connection standing between the reader and a definition.

Open-source readers skip that entirely. F-Droid alone now lists more than 3,800 fully open-source Android apps, and a handful exist specifically to open dictionary files stored on the device, no account and no ongoing connection required.

Finding the right one is not simple, though. Dictionary file formats are not interchangeable between readers, several apps share near-identical names, and some listings marketed as “offline dictionary” only cache a word after you look it up online first. The seven apps below were checked against their GitHub repositories and F-Droid listings for real install size, license, and update history, so what follows reflects what actually ships, not what a store description claims.

Quick Comparison: Open-Source Offline Dictionary Apps for Android

Challenges With Finding a True Open-Source Dictionary App

Picking a genuinely offline, open-source dictionary app runs into five recurring problems.

• The reader and the dictionary are two separate downloads. An app like OSS-Dict or QDict ships empty, and it still needs a slob, StarDict, or MDX file sourced separately before it shows a single definition.
• Formats do not cross over. A StarDict file will not open in a slob-only reader, and an MDX dictionary needs an MDict-compatible app, so the reader picked decides which dictionary files can actually load.
• Google Play’s dictionary results skew commercial. Most top listings bundle ads, in-app purchases, or a subscription just to lift a daily word limit, working against the point of a free, open dictionary.
• Naming collisions. Multiple unrelated “QDict” forks and generic “Dictionary” repositories exist across GitHub and F-Droid, so confirming the exact package ID and developer matters before installing.
• Stale forks outnumber maintained ones. StarDict-era readers were popular between 2010 and 2015 and many have not been touched since, so checking the last commit or F-Droid update date is the only reliable filter.

1. OSS-Dict

OSS-Dict is a Material Design 3 fork of Aard 2, built by developer farfromrefug, and it reads more dictionary formats than any other app on this list: slob, MDict, and StarDict/GoldenDict files all open in the same reader. The GitHub repository shows 172 stars and a commit pushed June 29, 2026, making it the most recently updated app here. It installs at 2.8 MB and needs Android 7.0 or newer.

Best for: Anyone who wants one reader that opens virtually any open dictionary format without juggling multiple apps.

Price: Free

• Punctuation, diacritics, and case-insensitive lookup
• Automatic history plus manual bookmarking, with custom CSS stylesheets for article display
• MathJax rendering for dictionaries with formulas, and volume-button navigation between results
• Distributed through F-Droid, IzzyOnDroid, GitHub Releases, and Obtainium

Strengths

• Widest format support of any reader on this list, so it works with slob, MDict, and StarDict libraries at once
• Most actively maintained project here, with commits within the last month
• Smallest install size among the multi-format readers

Weaknesses

• Dictionary files still need sourcing separately, from the slob wiki, FreeMdict forums, or the Huzheng StarDict archive
• Android 7.0 floor rules out some older devices that Aard 2 or QDict still support

2. QuickDic

QuickDic, maintained by developer Reimar Doeffinger as a revival of the original quickdic-dictionary project, is the only app here that builds its own dictionaries in-app rather than requiring a separately sourced file. It pulls from Wiktionary and Beolingus data, installs at 13 MB, and supports Android 5.0 and newer. The GitHub repository carries 392 stars and shipped its latest release, version 5.8.2, in November 2025.

Best for: Bilingual learners who want ready-made Wiktionary-based dictionaries without hunting for compatible files themselves.

Price: Free

• Downloads dictionary files from inside the app instead of requiring a manual file search
• Covers dozens of Wiktionary language pairs plus Beolingus German dictionaries
• Network access is only used to fetch dictionary files, never for the lookups themselves once downloaded
• Licensed Apache 2.0, with source hosted on GitHub since the Google Code migration

Strengths

• Removes the file-hunting step that every other reader on this list requires
• Broad language-pair coverage sourced straight from Wiktionary
• Long project history going back to the original Google Code quickdic-dictionary release

Weaknesses

• Largest install size on this list at 13 MB
• Own dictionary format is not compatible with slob, MDX, or StarDict files from other sources

3. Aard 2

Aard 2, built by developer Igor Tkach, is the original slob-format reader that OSS-Dict later forked, and it carries the largest following on this list at 544 GitHub stars. It installs at 3.3 MB, runs on Android 4.4 and newer, the lowest floor of any app here, and renders articles through a local embedded web server rather than a native view.

Best for: The oldest phones on this list, plus anyone who wants the reader with the longest track record and the largest library of ready-made slob dictionaries.

Price: Free (donation-supported)

• Case, punctuation, and diacritics-insensitive lookup across every loaded dictionary
• History tracking, manual bookmarking, and custom stylesheet support
• MathJax formula rendering and volume-button result navigation
• Available on F-Droid and Google Play, with dictionary files added through Android’s file picker

Strengths

• Lowest Android version requirement on this list, reaching phones as old as Android 4.4
• Largest and longest-running community of slob dictionary conversions to draw from
• Most GitHub stars of any app covered here, a sign of a well-tested codebase

Weaknesses

• Last tagged release was July 2024, so newer Android quirks land in OSS-Dict’s fork first
• Only reads slob files, not StarDict or MDX libraries directly

4. Ciyue

Ciyue, developed by mumu-lhl and distributed through F-Droid under a Material You interface, is built specifically around the MDX/MDD format that powers most commercial language-learning dictionaries once they are converted for personal offline use. It installs at 12 to 13 MB, needs Android 7.0 or newer for the latest release, and last updated in March 2026.

Best for: Readers who already have MDX dictionaries, since Ciyue is the most polished MDX-first reader on this list.

Price: Free

• Native MDX/MDD support with multi-dictionary search and a Material You interface
• Word bookmarking and built-in text-to-speech for pronunciation
• Optional AI translation through OpenAI, Gemini, or Deepseek, kept separate from core lookups
• MIT-licensed, with source published at github.com/mumu-lhl/Ciyue

Strengths

• Cleanest interface of any app on this list, following Android’s Material You system theming
• Direct support for the MDX libraries widely shared in language-learning communities
• MIT license, the least restrictive on this list for reuse or auditing

Weaknesses

• Core dictionary lookup stays offline, but the optional AI translation feature calls a non-free external service
• No slob or StarDict support, so existing libraries in those formats need converting first

5. QDict

QDict is a StarDict-only reader, packaged for F-Droid as a fork maintained by marmistrz, installing at just 4.1 MB and running on Android 4.2 or newer. Dictionaries load from a folder placed at /sdcard/QDict/dicts, with each StarDict set kept in its own subfolder.

Best for: StarDict purists who already have a folder of .ifo/.idx/.dict files and want the lightest possible reader for them.

Price: Free

• Three search modes: glob-style pattern matching, fuzzy query, and full-text search
• Reads the huge existing library of StarDict conversions, including the Huzheng archive
• Apache 2.0 license, with the F-Droid build removing the tracking libraries some older forks carried

Strengths

• Second-lowest Android floor on this list at 4.2, close behind Aard 2
• Direct compatibility with the largest existing StarDict file archive online
• Small, focused codebase with no bundled extras beyond dictionary lookup

Weaknesses

• Development has slowed; the F-Droid build’s last commit predates most other apps on this list
• Manual folder setup for dictionary files is less friendly than apps with an in-app browser

6. dikt

dikt, built by developer Maxim Saplin with Flutter, ships to Android, iOS, desktop, and web from one codebase, and comes preloaded with WordNet 3 out of the box. Its own IKV format loads fast: the project claims 90-plus dictionaries totaling more than 6 million words load in about 1.5 seconds, with individual lookups under 15 milliseconds.

Best for: Anyone who wants a large personal dictionary stack, bilingual files plus WordNet, searchable one-handed on a large-screen phone.

Price: Free

• Bottom-up interface designed to keep every control reachable by a thumb
• Imports JSON directly, with DSL, StarDict, and other formats convertible through the PyGlossary tool
• WordNet 3 bundled by default, so it works as a full English dictionary with no setup
• MIT-licensed and cross-platform, with the same dictionary files usable on desktop builds too

Strengths

• Fastest lookup speed claimed of any app on this list, even across a large multi-dictionary stack
• Only app here usable across Android, iOS, and desktop with the same dictionary files
• Comes with a working English dictionary preloaded, no separate file needed to get started

Weaknesses

• Non-native formats require a PyGlossary conversion step on a computer first
• Smallest GitHub community on this list among actively maintained apps, with 46 stars

7. freeDictionaryApp

freeDictionaryApp, a Kotlin and Jetpack Compose rewrite of developer Yamin Siahmargooei’s earlier Owl2 project, pulls definitions from the Free Dictionary API and the Wiktionary API rather than shipping a bundled file. It installs at 3.2 MB, supports Android 6.0 and newer, and its GitHub repository was last pushed on July 14, 2026, the most recent update of any app in this roundup.

Best for: Readers who want live, frequently updated Wiktionary-quality definitions and do not mind one online lookup per new word before it is cached offline.

Price: Free

• Text-to-speech pronunciation on top of word type, definitions, and usage examples
• Every word looked up gets stored locally, so repeat lookups work without a connection
• GPLv3-licensed with a clean Compose interface and no ads

Strengths

• Most frequently updated project in this roundup, with commits as recent as this week
• Draws directly from live Wiktionary data instead of a fixed dictionary snapshot
• Smallest, cleanest interface among the seven apps covered

Weaknesses

• Not offline-first: the first lookup of any word requires a connection before it is cached
• Offline coverage is limited to whatever has already been searched, not a full dictionary

How to Pick the Right Open-Source Dictionary App

Start with the dictionary files already owned or wanted. MDX libraries point to Ciyue, StarDict archives point to QDict or OSS-Dict, and slob files point to Aard 2 or OSS-Dict.

Check the last commit date before the star count. QuickDic, OSS-Dict, and freeDictionaryApp all shipped updates within the past year, while QDict and Aard 2 lean on older, more stable codebases instead.

On an older or storage-constrained phone, match the Android floor and install size to the device first; Aard 2 and QDict both run on Android 4.x hardware that OSS-Dict and Ciyue will not install on. For more apps that run light on older phones, that comparison covers launchers, browsers, and media players built the same way.

Anyone who wants a dictionary that never needs a live lookup, not even for the first search, should treat freeDictionaryApp as the exception on this list rather than the default, and lean on OSS-Dict or QuickDic instead.

Pairing a fully offline dictionary with a browser, launcher, and gallery built the same way stretches a limited data plan even further; see other apps that work fully offline for more picks that need no account and no connection.