# Fartlek Interval Trainer vs Sun Ring

The clearest difference is in-app purchases: Sun Ring at none against Fartlek Interval Trainer's 4. Sun Ring also leads on iOS requirement (17.0 vs 26.0). On price, ads and device support there is nothing between them.

Both are free to download. Fartlek Interval Trainer sells 4 in-app purchases, starting at $0.99 per month. Sun Ring asks for nothing beyond the download.

## The numbers

| Metric | Fartlek Interval Trainer | Sun Ring |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/sun-ring/id6751605890/reviews)** |
| Number of ratings | — | **1** |
| Positive reviews | 75.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 9 days | — |
| Monetization | Freemium | **Free** |
| Size | 86 MB | 2 MB |
| Requires iOS | 26.0 | **17.0** |
| Devices | iPhone, Apple Watch | iPhone, Apple Watch |
| Age rating | 4+ | 4+ |
| Developer | [Richard English](https://appshunter.io/developer/1537547687) | [Aaron Taylor](https://appshunter.io/developer/1616034086) |

## What reviewers say

### Fartlek Interval Trainer

[App page](https://appshunter.io/ios/app/fartlek-interval-trainer/id1537547685)

This running app automatically detects spontaneous intervals during Fartlek runs, providing live color-coded feedback on your effort. It also functions as a powerful timer for structured workouts like HIIT and Tabata, offering detailed metrics and syncing with Strava and Apple Health.

**Highlights:** Auto-detection of Fartlek intervals, Live color-coded effort feedback, Structured workout timer (HIIT, Tabata), Detailed interval metrics, Strava and Apple Health integration, Advanced effort level detection

**Features:** macOS Compatibility, Family Sharing, Apple Watch app, Vision Pro support

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly | $0.99 | per month |
| Annual | $6.99 | per year |
| RemoveAds | $0.99 | one-time |
| Lifetime | $14.99 | one-time |


### Sun Ring

[App page](https://appshunter.io/ios/app/sun-ring/id6751605890)

This app encourages daily sun exposure by using a familiar ring-closing mechanic. Users can customize their daily goals and track progress with watch face complications and notifications. Review historical data to maintain streaks and stay motivated to enjoy the outdoors.

**Highlights:** Gamified daily sun exposure tracking, Customizable daily sun exposure goals, Adjustable 'direct sunlight' lux value, Watch face widgets and complications, Goal completion notifications, Daily progress history and streak tracking

**In-app purchases:** none


## Frequently asked questions

### Is Fartlek Interval Trainer free?

Fartlek Interval Trainer is free to download, with in-app purchases available.

### Is Sun Ring free?

Sun Ring is free to download, with no in-app purchases.

### Do Fartlek Interval Trainer or Sun Ring have ads?

Neither Fartlek Interval Trainer nor Sun Ring 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.*