# JavaScript Studio Pro vs ECD Calculator

The clearest difference is price: ECD Calculator at Free against JavaScript Studio Pro's $12.99. ECD Calculator also leads on update cadence (every 5 days vs every 20 months) and ratings volume (5 vs 1). JavaScript Studio Pro's advantage is in-app purchases (none vs 2) and iOS requirement (10.0 vs 15.1). On rating, ads and device support there is nothing between them.

ECD Calculator is free to download; JavaScript Studio Pro costs $12.99 up front. ECD Calculator sells 2 one-off in-app purchases. JavaScript Studio Pro asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 5.0 for JavaScript Studio Pro against 5.0 for ECD Calculator. That said, the two scores are not equally well evidenced: ECD Calculator has 5 ratings behind it against 1, so its average is the more settled of the two.

JavaScript Studio Pro ships an update every 20 months, ECD Calculator every 5 days. The most recent releases landed on September 29, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | JavaScript Studio Pro | ECD Calculator |
| --- | --- | --- |
| Price | $12.99 | **Free** |
| Rating | [5.0 (1 ratings)](https://appshunter.io/ios/app/javascript-studio-pro/id1533537039/reviews) | [5.0 (5 ratings)](https://appshunter.io/ios/app/ecd-calculator/id6754762850/reviews) |
| Number of ratings | 1 | **5** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 20 months | **Every 5 days** |
| Monetization | Paid | **Free** |
| Size | 33 MB | 45 MB |
| Requires iOS | **10.0** | 15.1 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 17+ |
| Developer | [Arrowat LLC](https://appshunter.io/developer/1358562640) | [Drillsoft LLC](https://appshunter.io/developer/1787962403) |

## What reviewers say

### JavaScript Studio Pro

[App page](https://appshunter.io/ios/app/javascript-studio-pro/id1533537039)

Develop web applications on your mobile device using JavaScript, CSS, and HTML. This tool offers error checking assistance as you code, ensuring you don't lose track of your ideas. Create and save your projects anywhere, anytime.

**Highlights:** Write JavaScript, CSS, HTML code, Create web applications, Error checking assistance, Save code and ideas, Mobile development environment

**Features:** macOS Compatibility

**In-app purchases:** none


### ECD Calculator

[App page](https://appshunter.io/ios/app/ecd-calculator/id6754762850)

This utility app assists drilling and mud engineers in calculating Equivalent Circulating Density (ECD) at any point during operations. It offers a streamlined process with just a few clicks.

**Highlights:** ECD calculation, Drilling engineering, Mud engineering, Point-of-operation calculation, Streamlined interface

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 50 credits | $3.99 | one-time |
| 300 Credits | $9.99 | one-time |


## Frequently asked questions

### Is JavaScript Studio Pro free?

JavaScript Studio Pro costs $12.99, with no in-app purchases.

### Is ECD Calculator free?

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

### Which has better reviews, JavaScript Studio Pro or ECD Calculator?

JavaScript Studio Pro and ECD Calculator are both rated 5.0 out of 5 on the App Store, from 1 and 5 ratings respectively.

### Do JavaScript Studio Pro or ECD Calculator have ads?

Neither JavaScript Studio Pro nor ECD Calculator shows ads.

### Which is updated more often, JavaScript Studio Pro or ECD Calculator?

JavaScript Studio Pro ships an update every 20 months, and ECD Calculator every 5 days. Most recently, JavaScript Studio Pro was updated on September 29, 2026 and ECD Calculator on October 1, 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.*