# IDC Spring Calculator vs SendLynx

The clearest difference is rating: SendLynx at 5.0 against IDC Spring Calculator's 2.6. SendLynx also leads on update cadence (every 3 days vs every 2 months). IDC Spring Calculator's advantage is ratings volume (12 vs 1). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

SendLynx holds the better App Store score, 5.0 against 2.6. That said, the two scores are not equally well evidenced: IDC Spring Calculator has 12 ratings behind it against 1, so its average is the more settled of the two.

IDC Spring Calculator ships an update every 2 months, SendLynx every 3 days. Both last shipped on October 10, 2026.

## The numbers

| Metric | IDC Spring Calculator | SendLynx |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [2.6 (12 ratings)](https://appshunter.io/ios/app/idc-spring-calculator/id970455550/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/sendlynx/id6782413356/reviews)** |
| Number of ratings | **12** | 1 |
| Positive reviews | 22.2% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 3 days** |
| Monetization | Free | Free |
| Size | 1 MB | 31 MB |
| Requires iOS | **17.0** | 18.0 |
| Devices | **iPhone, iPad** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Zen Software, LLC](https://appshunter.io/developer/570584501) | [Austin Lutz](https://appshunter.io/developer/1884796552) |

## What reviewers say

### IDC Spring Calculator

[App page](https://appshunter.io/ios/app/idc-spring-calculator/id970455550)

This application allows users to engineer springs on demand. It provides access to a variety of spring types and materials, backed by a company with multiple manufacturing plants for efficient delivery.

**Highlights:** On-demand spring engineering, Variety of spring types, Multiple material options, Access to company manufacturing locations, Streamlined ordering process

**Features:** macOS Compatibility

**In-app purchases:** none


### SendLynx

[App page](https://appshunter.io/ios/app/sendlynx/id6782413356)

Easily book appointments with local service providers and manage your schedule. Business owners can streamline operations, manage clients, and process payments directly through the app.

**Highlights:** Book appointments instantly, Reschedule or cancel bookings, Rebook past visits with one tap, Passwordless sign-in, Manage calendar and bookings, Process payments securely, Manage services and staff

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

**In-app purchases:** none


## Frequently asked questions

### Is IDC Spring Calculator free?

IDC Spring Calculator is free to download, with no in-app purchases.

### Is SendLynx free?

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

### Which has better reviews, IDC Spring Calculator or SendLynx?

SendLynx is rated higher. IDC Spring Calculator averages 2.6 out of 5 from 12 ratings, while SendLynx averages 5.0 from 1 ratings.

### Do IDC Spring Calculator or SendLynx have ads?

Neither IDC Spring Calculator nor SendLynx shows ads.

### Which is updated more often, IDC Spring Calculator or SendLynx?

IDC Spring Calculator ships an update every 2 months, and SendLynx every 3 days. Most recently, IDC Spring Calculator was updated on October 10, 2026 and SendLynx on October 10, 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.*