# 51SMT vs Crisp

The clearest difference is iOS requirement: 51SMT at 13.0 against Crisp's 17.0. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. 51SMT sells 3 one-off in-app purchases and Crisp sells 4 in-app purchases, starting at $2.99 per 7 days. Whichever you choose, the download price is not the number that matters.

51SMT ships an update every 3 weeks, Crisp every 2 months. The most recent releases landed on November 3, 2026 and October 28, 2026 respectively.

## The numbers

| Metric | 51SMT | Crisp |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 3 weeks** | Every 2 months |
| Size | 55 MB | 3 MB |
| Requires iOS | **13.0** | 17.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [SHENZHEN 51 SURFACE MOUNTING TECHNOLOGY CO., LTD.](https://appshunter.io/developer/1470013387) | [ZHENGQIAO JIANG](https://appshunter.io/developer/1892168889) |

## What reviewers say

### 51SMT

[App page](https://appshunter.io/ios/app/51smt/id1470013388)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 周会员 | $0.99 | one-time |
| 月会员 | $0.99 | one-time |
| 季度会员 | $2.99 | one-time |


### Crisp

[App page](https://appshunter.io/ios/app/crisp-water-eject/id6767547524)

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weekly | $2.99 | per 7 days |
| Monthly | $5.99 | per month |
| Yearly | $34.99 | per year |
| Lifetime | $99.99 | one-time |


## Frequently asked questions

### Is 51SMT free?

51SMT is free to download, with in-app purchases available.

### Is Crisp free?

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

### Do 51SMT or Crisp have ads?

Neither 51SMT nor Crisp shows ads.

### Which is updated more often, 51SMT or Crisp?

51SMT ships an update every 3 weeks, and Crisp every 2 months. Most recently, 51SMT was updated on November 3, 2026 and Crisp on October 28, 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.*