# NULL Memo vs Perfect Lock

The clearest difference is iOS requirement: NULL Memo at 16.6 against Perfect Lock's 18.4. On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. NULL Memo sells 1 one-off in-app purchase and Perfect Lock sells 2 in-app purchases, starting at $1.99 per month. Whichever you choose, the download price is not the number that matters.

## The numbers

| Metric | NULL Memo | Perfect Lock |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Daily | — |
| Size | 60 MB | 12 MB |
| Requires iOS | **16.6** | 18.4 |
| Devices | iPhone | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Aaron Chan](https://appshunter.io/developer/1888707957) | [yunosuke yata](https://appshunter.io/developer/6787603181) |

## What reviewers say

### NULL Memo

[App page](https://appshunter.io/ios/app/null-memo-ideas-notes-lists/id6761292505)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| NULL Memo Pro | $2.99 | one-time |


### Perfect Lock

[App page](https://appshunter.io/ios/app/perfect-lock-screen-time/id6787911742)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Perfect Lock | $1.99 | per month |
| Perfect Lock | $29.99 | per year |


## Frequently asked questions

### Is NULL Memo free?

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

### Is Perfect Lock free?

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

### Do NULL Memo or Perfect Lock have ads?

Neither NULL Memo nor Perfect Lock shows ads.

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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.*