# SD Primer vs System Design Refresher

The clearest difference is in-app purchases: System Design Refresher at none against SD Primer's 2. SD Primer's advantage is update cadence (every 5 days vs monthly) and iOS requirement (17.0 vs 26.2). On price, ads and device support there is nothing between them.

Both are free to download. SD Primer sells 2 in-app purchases, starting at $9.99 per month. System Design Refresher asks for nothing beyond the download.

SD Primer ships an update every 5 days, System Design Refresher monthly. The most recent releases landed on August 4, 2026 and September 12, 2026 respectively.

## The numbers

| Metric | SD Primer | System Design Refresher |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 5 days** | Monthly |
| Size | 20 MB | 18 MB |
| Requires iOS | **17.0** | 26.2 |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Ernesto Hilvano](https://appshunter.io/developer/1740292069) | [Saurabh Sharma](https://appshunter.io/developer/1883599017) |

## What reviewers say

### 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 |


### System Design Refresher

[App page](https://appshunter.io/ios/app/system-design-refresher/id6760277935)

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

**In-app purchases:** none


## Frequently asked questions

### Is SD Primer free?

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

### Is System Design Refresher free?

System Design Refresher is free to download, with no in-app purchases.

### Do SD Primer or System Design Refresher have ads?

Neither SD Primer nor System Design Refresher shows ads.

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

SD Primer ships an update every 5 days, and System Design Refresher monthly. Most recently, SD Primer was updated on August 4, 2026 and System Design Refresher on September 12, 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.*