# Periodic Table & Element Guide vs Zettelkasten

Periodic Table & Element Guide and Zettelkasten are too close to call on the numbers: across 6 compared parameters — price, update cadence, ads and in-app purchases among them — neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.

Both are free to download. Periodic Table & Element Guide sells 2 in-app purchases, starting at $3.99 per 7 days and Zettelkasten sells 2 in-app purchases, starting at $9.99 per 7 days. Whichever you choose, the download price is not the number that matters.

Periodic Table & Element Guide ships an update every 3 weeks, Zettelkasten monthly. The most recent releases landed on October 11, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | Periodic Table & Element Guide | Zettelkasten |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 3 weeks** | Monthly |
| Size | 8 MB | 6 MB |
| Requires iOS | 17 | 17.0 |
| Devices | **iPhone, iPad** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Courtney Rawlings](https://appshunter.io/developer/1832354689) | [Phuc Pham](https://appshunter.io/developer/1893081423) |

## What reviewers say

### Periodic Table & Element Guide

[App page](https://appshunter.io/ios/app/periodic-table-and-element-guide/id6758946775)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Periodic Pro Weekly | $3.99 | per 7 days |
| Periodic Pro Lifetime | $29.99 | one-time |


### Zettelkasten

[App page](https://appshunter.io/ios/app/zettelkasten-notes-graph/id6771281468)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weekly | $9.99 | per 7 days |
| Yearly | $49.99 | per year |


## Frequently asked questions

### Is Periodic Table & Element Guide free?

Periodic Table & Element Guide is free to download, with in-app purchases available.

### Is Zettelkasten free?

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

### Do Periodic Table & Element Guide or Zettelkasten have ads?

Neither Periodic Table & Element Guide nor Zettelkasten shows ads.

### Which is updated more often, Periodic Table & Element Guide or Zettelkasten?

Periodic Table & Element Guide ships an update every 3 weeks, and Zettelkasten monthly. Most recently, Periodic Table & Element Guide was updated on October 11, 2026 and Zettelkasten on October 10, 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.*