# Writebulb vs DutyLock

The clearest difference is update cadence: DutyLock at fortnightly against Writebulb's monthly. Writebulb's advantage is iOS requirement (15.5 vs 17.0). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Writebulb sells 1 one-off in-app purchase and DutyLock sells 5 in-app purchases, starting at $2.99 per 7 days. Whichever you choose, the download price is not the number that matters.

Writebulb ships an update monthly, DutyLock fortnightly. The most recent releases landed on October 10, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | Writebulb | DutyLock |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Monthly | **Fortnightly** |
| Size | 11 MB | 28 MB |
| Requires iOS | **15.5** | 17.0 |
| Devices | **iPhone, iPod** | iPhone |
| Age rating | 12+ | 4+ |
| Developer | [Brian Pirie](https://appshunter.io/developer/1676763468) | [FAT FIRE APPS](https://appshunter.io/developer/1654496945) |

## What reviewers say

### Writebulb

[App page](https://appshunter.io/ios/app/writebulb/id6446223818)

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| A Thousand Prompts | $2.99 | one-time |


### DutyLock

[App page](https://appshunter.io/ios/app/dutylock-screen-time-control/id6773041463)

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| DutyLock Pro Weekly | $2.99 | per 7 days |
| DutyLock Pro Monthly | $4.99 | per month |
| DutyLock Pro Annual | $49.99 | per year |
| DutyLock Pro Annual 50% First Year | $49.99 | per year |
| DutyLock Pro Lifetime | $99.99 | one-time |


## Frequently asked questions

### Is Writebulb free?

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

### Is DutyLock free?

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

### Do Writebulb or DutyLock have ads?

Neither Writebulb nor DutyLock shows ads.

### Which is updated more often, Writebulb or DutyLock?

Writebulb ships an update monthly, and DutyLock fortnightly. Most recently, Writebulb was updated on October 10, 2026 and DutyLock 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.*