# Undercurrent vs Truly Simple Symptom Log

The clearest difference is device support: Truly Simple Symptom Log at 3 against Undercurrent's 1. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Undercurrent sells 1 one-off in-app purchase and Truly Simple Symptom Log sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Undercurrent ships an update monthly, Truly Simple Symptom Log every 3 weeks. The most recent releases landed on October 6, 2026 and October 9, 2026 respectively.

## The numbers

| Metric | Undercurrent | Truly Simple Symptom Log |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Monthly | **Every 3 weeks** |
| Size | 76 MB | 1 MB |
| Requires iOS | **16.4** | 17.0 |
| Devices | iPhone | **iPhone, iPad, Mac** |
| Age rating | 12+ | 4+ |
| Developer | [Lloyd Rowat](https://appshunter.io/developer/1166734628) | [Colin Wright](https://appshunter.io/developer/1814828139) |

## What reviewers say

### Undercurrent

[App page](https://appshunter.io/ios/app/undercurrent-symptom-tracker/id6759209174)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Undercurrent Health: Pro | $19.99 | one-time |


### Truly Simple Symptom Log

[App page](https://appshunter.io/ios/app/truly-simple-symptom-log/id6766123526)

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlock Pro | $4.99 | one-time |


## Frequently asked questions

### Is Undercurrent free?

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

### Is Truly Simple Symptom Log free?

Truly Simple Symptom Log is free to download, with in-app purchases available.

### Do Undercurrent or Truly Simple Symptom Log have ads?

Neither Undercurrent nor Truly Simple Symptom Log shows ads.

### Which is updated more often, Undercurrent or Truly Simple Symptom Log?

Undercurrent ships an update monthly, and Truly Simple Symptom Log every 3 weeks. Most recently, Undercurrent was updated on October 6, 2026 and Truly Simple Symptom Log on October 9, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*