# 504 vs Smart Complex

The clearest difference is in-app purchases: Smart Complex at none against 504's 13. Smart Complex also leads on ads (none vs shown) and iOS requirement (12.0 vs 18.0). On price and device support there is nothing between them.

Both are free to download. 504 sells 12 in-app purchases, starting at $4.99 per 7 days. Smart Complex asks for nothing beyond the download.

## The numbers

| Metric | 504 | Smart Complex |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.8 (4.6K ratings)](https://appshunter.io/ios/app/504-vocabulary-builder/id1452101398/reviews)** | — |
| Number of ratings | **4.6K** | — |
| Positive reviews | 72.6% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | Fortnightly | — |
| Monetization | Free with in-app purchases | — |
| Size | 65 MB | 33 MB |
| Requires iOS | 18.0 | **12.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Nefarius Apps](https://appshunter.io/developer/1792473508) | [meisam mirahsan](https://appshunter.io/developer/1466980802) |

## What reviewers say

### 504

[App page](https://appshunter.io/ios/app/504-vocabulary-builder/id1452101398)

Master essential vocabulary with this language learning app. It offers clear definitions, example sentences, and native pronunciation for high-utility words. Engage with interactive games like flashcards and quizzes to reinforce learning and track your progress effectively.

**Highlights:** Essential vocabulary selection, Clear definitions and example sentences, Native pronunciation audio, Interactive learning games (flashcards, quizzes), Progress tracking tools, Multi-language support

**Features:** macOS Compatibility, Family Sharing, Vision Pro support

**In-app purchases (12)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium | $4.99 | per 7 days |
| Weekly Pro Membership | $8.99 | per 7 days |
| Weekly Premium Membership | $9.99 | per 7 days |
| Premium | $9.99 | per month |
| Premium | $9.99 | per month |
| Premium | $9.99 | per 7 days |
| Monthly Pro Membership | $17.99 | per month |
| Monthly Premium Membership | $19.99 | per month |
| Premium | $34.99 | per year |
| Yearly Premium Membership | $59.99 | per year |
| Yearly Pro Membership | $59.99 | per year |
| Lifetime Access | $79.99 | one-time |

**What reviewers like**

- 🚀 Easy to learn
- 👍 Useful vocabulary practice
- 🚀 Convenient for learning on the go

**What reviewers complain about**

- 🐛 Bugs and glitches in latest version
- 🔒 Concerns about data tracking
- 🔊 Issues with pronunciation and audio

**Reported bugs**

- Pronunciation not working in latest version
- Lessons for second half of book blocked behind paywall
- Compatibility issues with older devices

**Requested features**

- Add part of speech for each word
- Include a note box for personal examples
- Add dark mode option


### Smart Complex

[App page](https://appshunter.io/ios/app/smart-complex/id6737433975)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is 504 free?

504 is free to download, with in-app purchases available.

### Is Smart Complex free?

Smart Complex is free to download, with no in-app purchases.

### Do 504 or Smart Complex have ads?

504 shows ads; Smart Complex does not.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*