# UDAN EMS vs Ruler Studio

The clearest difference is in-app purchases: UDAN EMS at none against Ruler Studio's 1. Ruler Studio's advantage is iOS requirement (13.0 vs 15.0). On price, update cadence, ads and device support there is nothing between them.

Both are free to download. Ruler Studio sells 1 one-off in-app purchase. UDAN EMS asks for nothing beyond the download.

UDAN EMS ships an update every 5 weeks, Ruler Studio every 6 weeks. The most recent releases landed on November 3, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | UDAN EMS | Ruler Studio |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Every 5 weeks** | Every 6 weeks |
| Size | 34 MB | 19 MB |
| Requires iOS | 15.0 | **13.0** |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Anhui Udan Technology Co., Ltd.](https://appshunter.io/developer/1593792520) | [Spyridon Bousios](https://appshunter.io/developer/1168309944) |

## What reviewers say

### UDAN EMS

[App page](https://appshunter.io/ios/app/udan-ems/id6467070220)

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

**In-app purchases:** none


### Ruler Studio

[App page](https://appshunter.io/ios/app/ruler-studio/id6777489772)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Ruler Pro Lifetime | $2.99 | one-time |


## Frequently asked questions

### Is UDAN EMS free?

UDAN EMS is free to download, with no in-app purchases.

### Is Ruler Studio free?

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

### Do UDAN EMS or Ruler Studio have ads?

Neither UDAN EMS nor Ruler Studio shows ads.

### Which is updated more often, UDAN EMS or Ruler Studio?

UDAN EMS ships an update every 5 weeks, and Ruler Studio every 6 weeks. Most recently, UDAN EMS was updated on November 3, 2026 and Ruler Studio on October 31, 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.*