# Spine vs Understory

The clearest difference is in-app purchases: Spine at none against Understory's 6. On price, rating, review sentiment and ratings volume there is nothing between them.

Both are free to download. Understory sells 6 in-app purchases, starting at $4.99 per month. Spine asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 5.0 for Spine against 4.9 for Understory. Both are backed by a comparable volume of ratings — 86 and 63 respectively. Written reviews are what separate them: 100% of Spine's written reviews are positive against 96% of Understory's.

Spine ships an update weekly, Understory every 9 days. Both last shipped on November 9, 2026.

## The numbers

| Metric | Spine | Understory |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (86 ratings)](https://appshunter.io/ios/app/spine-book-tracker/id6759875368/reviews)** | [4.9 (63 ratings)](https://appshunter.io/ios/app/understory-reading-tracker/id6767701983/reviews) |
| Number of ratings | **86** | 63 |
| Positive reviews | **100.0% of reviews** | 95.8% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Weekly** | Every 9 days |
| Monetization | **Free** | Freemium |
| Size | 42 MB | 213 MB |
| Requires iOS | 17.0 | **16.4** |
| Devices | iPhone | iPhone |
| Age rating | 4+ | 12+ |
| Developer | [Tanner Flake](https://appshunter.io/developer/1810308106) | [Understory Studios LLC](https://appshunter.io/developer/1896501166) |

## What reviewers say

### Spine

[App page](https://appshunter.io/ios/app/spine-book-tracker/id6759875368)

Organize your reading life by creating tiered lists of books you've finished. Track your reading progress, see what friends are reading, and discover personalized recommendations.

**Highlights:** Create book tier lists, Track reading progress, Follow friends' reading habits, Discover personalized recommendations, Import Goodreads library, Log start and finish dates

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

**In-app purchases:** none


### Understory

[App page](https://appshunter.io/ios/app/understory-reading-tracker/id6767701983)

This app helps you track your reading progress, set goals, and build a consistent reading habit. It features a unique plant aesthetic and allows you to grow real-world trees by meeting reading objectives. Connect with friends, share recommendations, and view insightful reading statistics.

**Highlights:** Log reading progress and books, Set reading goals and streaks, Grow real-world trees by meeting objectives, Connect with friends and join book groups, Share book recommendations, View reading statistics and insights, Organize custom reading lists

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

**In-app purchases (6)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Understory Premium | $4.99 | per month |
| Understory Premium - Monthly | $4.99 | per month |
| Understory Premium | $49.99 | per year |
| Understory Premium - Yearly | $49.99 | per year |
| Streak Freeze | $0.99 | one-time |
| Streak Restore | $0.99 | one-time |


## Frequently asked questions

### Is Spine free?

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

### Is Understory free?

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

### Which has better reviews, Spine or Understory?

Spine is rated higher. Spine averages 5.0 out of 5 from 86 ratings, while Understory averages 4.9 from 63 ratings.

### Do Spine or Understory have ads?

Neither Spine nor Understory shows ads.

### Which is updated more often, Spine or Understory?

Spine ships an update weekly, and Understory every 9 days. Most recently, Spine was updated on November 9, 2026 and Understory on November 9, 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.*