Build a usable vocabulary for your job, studies, or hobbies with smart, spaced repetition reviews. Master real word usage and track your progress with clear statistics. Designed for serious learners with a clean interface and no gimmicks.
3.66
April 14, 2026
Bug fixes and performance improvements.
Yearly subscription to the Basic Tier.
Codex4 uses FSRS, a modern spaced-repetition model, to time reviews precisely when you need them. This ensures efficient learning and long-term retention of vocabulary.
The app treats each word as a lemma, meaning it naturally covers different forms and conjugations as you progress. This helps you master the real usage of words.
Yes, you can add your own words from any text in one tap. This allows you to build a vocabulary tailored to your specific job, studies, or hobbies.
Codex4 offers Basic and Pro plans, available monthly or yearly. Yearly plans include free trial periods of 7 days for Basic and 3 days for Pro.
No, Codex4 does not contain advertisements. It is designed with a clean interface for serious learners, focusing on efficient study without distractions.
Yes, your data stays yours. You will retain access to your review progress even after unsubscribing, and you can export your words and learning data at any time.
Codex4 is currently supported on iPhone and iPod devices. It is designed for mobile learning on the go.
The latest version of Codex4 is 3.66, last updated on April 14, 2026. Updates ensure the app remains reliable and incorporates improvements for serious learners.
