flangu is a language-learning app that uses spaced repetition and flashcards to help you retain vocabulary efficiently. Think of it as a combination of Anki and Google Translator. Here's how it works:
flangu also provides tools to make language learning even more effective, including:
By combining translation, spaced repetition and above tools, flangu helps you build your vocabulary faster, remember it longer and learn language more effectively.
Spaced repetition is a learning method that helps you remember information better by reviewing it at increasing intervals. When you first learn something new, you review it more often. As you remember it better, the reviews become less frequent. This method ensures you revisit information just before you might forget it, helping it stay in your long-term memory.
flangu uses spaced repetition with algorithm FSRS-5. The app adjusts the timing of reviews based on how well you remember each flashcard. Cards you find difficult appear more often, while easier ones appear less frequently. This personalized approach makes your studying more efficient.
Using spaced repetition with flangu helps you keep vocabulary and language concepts fresh in your memory, making language learning faster and more effective.
The core goal of FSRS-5 is to maintain a high retention rate — meaning you remember what you’ve learned without needing constant repetition. By default, flangu is set to aim for 90% retention, which strikes a balance between long-term memory and review efficiency.
You can customize this in Settings → Retention, where you can set your target anywhere between 0.70 and 0.99:
A range of 80%–95% is generally recommended, with 90% as the default and most commonly used setting.
By adjusting your target retention, you can fine-tune the trade-off between efficiency and mastery based on your learning goals.
To get the most out of FSRS-5, it's important to optimize the algorithm using your own review data. Optimization fine-tunes FSRS’s 19 parameters based on how you learn and forget, so the scheduler can better predict when you’re likely to forget something and adjust review timing accordingly.
Why optimize? Because everyone’s memory is different—some cards are harder, some easier, and your recall speed may not match the default model. By optimizing, you're letting the algorithm learn how you retain information, which leads to:
To run an optimization, you’ll need at least 512 reviews in your history (this gives the model enough data to learn from). If you're using flangu regularly, optimizing once a month is a great habit—it keeps the scheduler aligned with your current learning pace and memory strength. You can optimize the algorithm using our FSRS Optimizer — just go to Settings → Optimize Algorithm to get started.
Cards are the core of the app. They contain the vocabulary you’ve collected or want to learn. Each card has a front and back, typically representing the word or phrase and its translation.
You can create cards manually, entering both sides yourself, or use the built-in translator to automatically generate a translation — just type the front, and the back is filled in for you. You can easily switch between manual and translator mode using the toggle button in the top-left corner of the card creation view.
Since flangu is built for language learning, each card also includes a front language and a back language to better support multilingual vocab building.
Each card comes with helpful features to deepen your learning:
Once you create a card, it’s immediately added to your review queue — ready to be reinforced with FSRS-5. You can edit created cards later by navigating to Decks, selecting the deck with the card, and clicking on the card. Every card has its own statistics, so you can track your progress.
Note: To create a card you have to select at least one deck to store it in.
Decks are collections of cards grouped by a common theme, like "Business English" or "French Idioms". They help you organize your vocabulary in a way that makes sense for your goals or interests.
You can create a new deck either from the card creation view (using the + button in the top-right corner) or directly in the Decks view. Each deck can have an optional description, making it easier to remember what it's for.
Every deck has its own statistics, so you can track your progress and see how well you're doing within that specific topic.
When you review, you study all cards from a deck in a single session. On your dashboard, you'll see which decks are due for review today.
Reviews are where the real learning happens. Powered by the FSRS-5 algorithm, flangu schedules your cards for review at optimal times — just before you're likely to forget them. This makes your study sessions more effective and efficient.
During each review, you’ll see the front of the card first, then tap to reveal the back. After that, you'll rate how well you remembered it using one of four buttons:
These ratings help FSRS-5 adjust the next review interval based on how confidently you recalled the card.
Note: If you press "Hard" by mistake when failing to recall, FSRS extends review intervals, thinking you've recalled with difficulty. This misjudgment disrupts your study efficiency. Always choose "Again" for failed recalls to keep review intervals properly aligned with your learning pace.
While reviewing, you can use all card features to reinforce your understanding:
Need to make a quick correction? You can edit a card directly during review by clicking on the back side.
The Dashboard is the central place to manage your daily learning and track your overall progress in flangu. It gives you a clear snapshot of what you’ve accomplished today — and what’s still waiting.
Here’s what you’ll find on the Dashboard:
Whether you're reviewing just a few words or diving into multiple decks, the Dashboard helps you stay focused, organized, and in control of your learning journey.
flangu provides in-depth statistics to help you understand your learning habits, track progress, and stay motivated. Stats are organized into four layers, each giving you a different level of detail:
Stats are organized into four layers, each giving you a different level of detail:
These appear at the end of a review session for a specific deck on a specific day. They include:
Each card has its own history, including:
Every deck has its own set of metrics:
Charts:
This is the big picture — your full learning journey across all decks:
Charts:
These detailed stats and charts not only give you insight into your learning behavior, but also help you stay consistent, spot trends, and celebrate your progress.
flangu supports a wide range of languages, making it easy to build your vocabulary across different scripts and cultures. You can select a front language and a back language for each card, allowing flexible combinations for study.
For languages with non-Latin scripts, flangu offers romanization to assist with reading and pronunciation. Romanization is available for: