Developer Resources

Dictionary Data

• wiktextract - A very high quality extracted JSON version of Wiktionary, with the English one containing over 8 million entries in 300+ languages with a huge amount of metadata. Supports currently 6 Wiktionaries, download the extracted data here.
• Ultimate Dictionary API - A free dictionary API that supports all languages.
• The KOReader dictionary list - Direct links to hundreds of free Stardict dictionaries.
• pyglossary - Amazing library for the creation and conversion of dictionaries in a huge amount of formats.
• wordnet-as-a-service - A REST interface for WordNet.
• Proficiency - A library that extracts short definitions from kaikki data.
• dictcc-stardict - Tool to convert the dict.cc dictionaries to stardict format.

Frequency Lists

• wordfreq - A great Python library that contains frequency data for 44 languages.

Image generation

• Stable diffusion - An amazing open source generator that made huge waves on its release.
• AUTOMATIC1111's webui - This is what you should install if you want to use Stable Diffusion locally.
• Camenduru's notebooks - A simple one click way to use Stable Diffusion on Google Colab (if you don't have a good graphics card).
• civitai - A website that contains all kinds of models, optimized for different aesthetics.

NLP

• spaCy - A great library that can do everything: tokenization, lemmatization, named entity recognition, and much more.

Other Great Projects

• WantWords - A reverse dictionary that can find words based on the definitions you type (and works surprisingly well).

Speech To Text

• Whisper - OpenAI's amazing project that delivers extremely good results (except for low-resource languages).
• whisper.cpp - A version of Whisper that runs much faster on the CPU, it even supports browser through WASM.

Text To Speech

• edge-tts - A Python library the uses the reverse engineered Text To Speech API of the Edge browser, producing extremely high quality output.
• Coqui TTS - An entirely open source Python library running locally.

Translation

• LibreTranslate
• OpenNMT-py
• Argos-Translate

Language Learning

Anki (Flashcards)

• AnkiDroid - The free Anki Android client for the most popular flashcard software - the desktop version is free as well.
• vocabsieve - A program that allows to easily add sentences you read to Anki. Per flashcard the focus always lies on one word, with automatically fetched translations + pronunciation.
• tatoeba-to-anki - A project that allows you to generate Anki decks with translations.
• ankigenbot - A telegram bot that automatically creates Anki flashcards for words you send to it.
• FSRS4Anki - An optimized spaced repetition algorithm that should minimize review time.
• vocage - A spaced repetition program in the terminal

Chatbots

• ChatGPT - very good for practicing a wide variety for languages. Especially with the new version that can listen and reply to you in voice (freely available in the app).

Chrome Extensions

• word-discoverer - An extension that highlights rare words in texts.
• pronounce - An extension that correctly pronounces words.

Courses

• Language Transfer - An app that offers completely free audio courses for several languages.

Dictionaries

• wikdict-gen - For 20 popular languages this project offers a downloadable dictionary in many formats for each language pair.
• Wiktionary-Dictionaries - Dictionaries extracted from the English Wiktionary, supporting 300+ languages with definitions in English.
• dictionariez - A browser extension to look up words on web pages.
• ebook-reader-dict - 14 monolingual dictionaries extracted from Wiktionary in several languages.

Language Learning Games

• Game2Text - A program that makes it easy to look up words in Visual Novels.
• LibreLingo - An open-source Duolingo-like game.

Learning With Texts (LinQ-like)

• lwt - A self-hosted version (requires a bit of effort to get running) with a long history.
• Lute - Learning Using Texts (Lute). A partial rewrite of lwt.
• trunk - Very pretty UI, works pretty well (although the author says it's unstable) and supports 8 languages.

Open Source Games (with a lot of text and translations)

• Unciv - Awesome strategy game (Civ 5 remake) with very low resource requirements and great desktop + mobile support.
• Shattered Pixel Dungeon - Very polished roguelike with pixel graphics and desktop + mobile support.
• Widelands - A strategy game inspired by Settlers 2.
• Pathos - A roguelike game with desktop + mobile support inspired by Nethack.
• Cataclysm: Dark Days Ahead - A zombie roguelike game with a huge amount of content.
• 0 A.D. - A strategy game inspired by Age Of Empires.
• Battle of Wesnoth - Turn based strategy game with a huge amount of content.
• OpenTTD - A simulation game based upon Transport Tycoon Deluxe.
• Veloren - A voxel RPG inspired by Cube World and Minecraft.

Reader Programs or extensions

• tachiyomi - An manga reader that can fetch manga in many different languages.
• KOReader - An open source ebook reader app that runs on many devices and has a lot of integrated dictionaries that can be downloaded with one click.
• WordDumb - A program that edits ebooks so that simplified definitions are shown over complicated words. It also supports generating Kindle X-Ray.
• fluentcards - A website that allows you to turn your kindle lookups into Anki flashcards

Video Players (or extensions)

• mpvacious - Allows you to automatically create Anki flashcards out of the TV shows you are watching.
• Immersive - A similar program to mpvacious.
• voracious - A video player that has several features directed at language learning.
• subadub - An extension for Netflix that allows downloading SRT and makes them copyable (so that you can look up the words).

Useful Resources

Other Great Projects

• Free Language Tools Wiki - Has a lot of useful tips and links, written by the vocabsieve maintainer.
• Low resource languages - A Github repo containing many links to projects about low resource languages
• Language-learning - A Github repo with many links to language learning resources