# 504 - Vocabulary Builder

> Word of the Day & Flashcards

Canonical page: [https://chrome-stats.com/d/id1452101398](https://chrome-stats.com/d/id1452101398)

## Overview

- **ID:** `id1452101398`
- **Platform:** Apple
- **Type:** Apple app
- **Status:** Available
- **Publisher:** Nefarius Apps
- **Category:** Education
- **Rating:** 4.80 / 5 (4,596 ratings)
- **Version:** 8.12.5
- **Last updated:** 2026-09-18
- **First published:** 2019-02-15
- **Size:** 65 MB
- **Data as of:** 2026-09-22
- **Store listing:** [Apple App Store](https://apps.apple.com/us/app/504-vocabulary-builder/id1452101398)
- **Website:** [https://nefarius.co](https://nefarius.co/)
- **Privacy policy:** [https://nefarius-apps.github.io/504/privacy-policy](https://nefarius-apps.github.io/504/privacy-policy)

## Description

504 Words is a language learning app that helps you master essential vocabulary through clear definitions, example sentences, and native pronunciation. Learn 504 high-utility words across English, German, and French with practical usage—perfect for real-world communication. The clean, ad-free interface keeps you focused on learning.

Practice with built-in study modes: flashcards, multiple-choice quizzes, and listening games to boost memory, comprehension, and pronunciation. Track your progress, see mastered words, and tailor your pace to your level. More languages will be added, making it a scalable tool for daily practice anywhere.

## Rankings

- #26,689 — Overall

## Review summary

Users praise the app for convenience and vocabulary practice, especially the card-based format and contextual sentences. However, several issues recur: pronunciation audio often fails or uses the wrong voice; premium pricing and late-access lockouts frustrate users; and updates bring bugs, lag, and UI problems. Overall, the app is useful for learning, but reliability and pricing clarity need improvement.

### Pros

- Very convenient to learn and review vocabulary anywhere on a mobile device, serving as a practical substitute for the book.
- The practice content helps with learning vocabulary and usage in context (sentences).
- Card-based format with examples and synonyms supports effective learning.
- General positive sentiment from users, with some reviewers calling it among the best vocabulary apps they have used.

### Cons

- Pronunciation and audio features often do not work correctly, with TTS using an English voice or failing to play pronunciation.
- Content and lessons become locked behind premium, with confusing pricing and reports of paying for access to later lessons.
- Bugs and stability issues in updates, including lag, display problems, and navigation quirks, plus missing PDFs or features on some devices.

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Source: [Chrome-Stats](https://chrome-stats.com/d/id1452101398)