# Stackbox vs OK Calendar

The clearest difference is in-app purchases: OK Calendar at none against Stackbox's 2. OK Calendar also leads on iOS requirement (16.4 vs 18.0). Stackbox's advantage is update cadence (every 4 days vs every 11 days). On price, ads and device support there is nothing between them.

Both are free to download. Stackbox sells 2 in-app purchases, starting at $1.99 per month. OK Calendar asks for nothing beyond the download.

Stackbox ships an update every 4 days, OK Calendar every 11 days. The most recent releases landed on October 10, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | Stackbox | OK Calendar |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 4 days** | Every 11 days |
| Size | 33 MB | 52 MB |
| Requires iOS | 18.0 | **16.4** |
| Devices | **iPhone, iPad, Mac** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [YunJae Jeong](https://appshunter.io/developer/1568287924) | [Nikolaos Pinatsis](https://appshunter.io/developer/1832444446) |

## What reviewers say

### Stackbox

[App page](https://appshunter.io/ios/app/stackbox-rss-reader/id6758572761)

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Plan | $1.99 | per month |
| Yearly Plan | $19.99 | per year |


### OK Calendar

[App page](https://appshunter.io/ios/app/ok-calendar/id6785077515)

**In-app purchases:** none


## Frequently asked questions

### Is Stackbox free?

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

### Is OK Calendar free?

OK Calendar is free to download, with no in-app purchases.

### Do Stackbox or OK Calendar have ads?

Neither Stackbox nor OK Calendar shows ads.

### Which is updated more often, Stackbox or OK Calendar?

Stackbox ships an update every 4 days, and OK Calendar every 11 days. Most recently, Stackbox was updated on October 10, 2026 and OK Calendar 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.*