Flexi: Vocabulary Builder is a vocabulary training app that combines AI-generated flashcards with spaced repetition so new words actually stick. It’s designed for quick daily practice and makes it easy to capture new vocabulary and review it on a schedule.
AI flashcards and customization
Flexi uses AI to generate key card content at no extra cost, and lets you tailor cards to your learning style.
AI-generated translation, usage example, and definition
Custom fields to match your study goals
Add your own notes and turn them into full flashcards later
Image generation for words (available for premium subscribers)
Spaced repetition, streaks, and pronunciation
The app uses an advanced spaced repetition system that increases review intervals over time to support long-term memory.
Spaced repetition scheduling for efficient reviews
Daily streak tracking to stay consistent and monitor progress
Built-in Text-to-Speech to hear correct pronunciation of words and phrases
Languages and iOS focus
Flexi supports English, Spanish, German, French, Russian, Arabic, Hebrew, Swedish, and Thai, with tight iOS integration for capturing words on the go and reviewing them later.

