# Trajectory vs LineConstants

The clearest difference is in-app purchases: Trajectory at none against LineConstants's 2. Trajectory also leads on update cadence (fortnightly vs every 2 months). LineConstants's advantage is ads (none vs shown). On price, device support and iOS requirement there is nothing between them.

Both are free to download. LineConstants sells 2 in-app purchases, starting at $9.99 per month. Trajectory asks for nothing beyond the download.

Trajectory ships an update fortnightly, LineConstants every 2 months. The most recent releases landed on October 11, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | Trajectory | LineConstants |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | Yes | **No** |
| Update frequency | **Fortnightly** | Every 2 months |
| Size | 36 MB | 33 MB |
| Requires iOS | **17.7.2** | 18.0 |
| Devices | iPhone | **iPhone, iPad** |
| Age rating | 4+ | 4+ |
| Developer | [Hideaki Uchikoshi](https://appshunter.io/developer/1559575002) | [Sergey Gussev](https://appshunter.io/developer/1784439395) |

## What reviewers say

### Trajectory

[App page](https://appshunter.io/ios/app/trajectory-detection/id6511212764)

**Features:** macOS Compatibility

**In-app purchases:** none


### LineConstants

[App page](https://appshunter.io/ios/app/lineconstants/id6740081204)

**Features:** macOS Compatibility, Family Sharing

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly | $9.99 | per month |
| Yearly | $19.99 | per year |


## Frequently asked questions

### Is Trajectory free?

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

### Is LineConstants free?

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

### Do Trajectory or LineConstants have ads?

Trajectory shows ads; LineConstants does not.

### Which is updated more often, Trajectory or LineConstants?

Trajectory ships an update fortnightly, and LineConstants every 2 months. Most recently, Trajectory was updated on October 11, 2026 and LineConstants on October 1, 2026.

---

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