# System Design interview prep vs SD Primer

The clearest difference is ads: SD Primer at none against System Design interview prep's shown. SD Primer also leads on update cadence (every 5 days vs monthly). On price, in-app purchases, device support and iOS requirement there is nothing between them.

Both are free to download. System Design interview prep sells 5 in-app purchases, starting at $3.99 per 7 days and SD Primer sells 2 in-app purchases, starting at $9.99 per month. Whichever you choose, the download price is not the number that matters.

System Design interview prep ships an update monthly, SD Primer every 5 days. The most recent releases landed on September 26, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | System Design interview prep | SD Primer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[1.0 (2 ratings)](https://appshunter.io/ios/app/system-design-interview-prep/id6756310915/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | Yes | **No** |
| Update frequency | Monthly | **Every 5 days** |
| Monetization | Free with in-app purchases | — |
| Size | 89 MB | 20 MB |
| Requires iOS | 17.6 | **17.0** |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Abdelhak El Moussaoui](https://appshunter.io/developer/1827690433) | [Ernesto Hilvano](https://appshunter.io/developer/1740292069) |

## What reviewers say

### System Design interview prep

[App page](https://appshunter.io/ios/app/system-design-interview-prep/id6756310915)

This app simulates system design interviews with an AI interrogator and interactive scenarios. Practice real-world architecture problems, receive instant feedback, and track your progress to ace your next tech interview.

**Highlights:** Interactive War Room for architecture scenarios, AI Interrogator challenges design decisions, Realistic system design interview questions, Daily practice drills for skill sharpening, Detailed performance analytics, Instant feedback and best practice learning

**Features:** macOS Compatibility

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlimited access | $3.99 | per 7 days |
| Unlimited access | $4.99 | per 7 days |
| Unlimited access | $6.99 | per month |
| Unlimited access | $12.99 | per month |
| Unlimited access | $99.99 | per year |


### SD Primer

[App page](https://appshunter.io/ios/app/sd-primer/id6758010557)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| SDPrimer Pro | $9.99 | per month |
| SDPrimer Pro | $99.99 | per year |


## Frequently asked questions

### Is System Design interview prep free?

System Design interview prep is free to download, with in-app purchases available.

### Is SD Primer free?

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

### Do System Design interview prep or SD Primer have ads?

System Design interview prep shows ads; SD Primer does not.

### Which is updated more often, System Design interview prep or SD Primer?

System Design interview prep ships an update monthly, and SD Primer every 5 days. Most recently, System Design interview prep was updated on September 26, 2026 and SD Primer on October 1, 2026.

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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.*