# What Doctors Know vs EDTNA/ERCA

The clearest difference is in-app purchases: EDTNA/ERCA at none against What Doctors Know's 14. EDTNA/ERCA also leads on update cadence (every 2 months vs every 4 months). What Doctors Know's advantage is iOS requirement (13.0 vs 15.0). On price, ads and device support there is nothing between them.

Both are free to download. What Doctors Know sells 14 in-app purchases, starting at $5.99 per year. EDTNA/ERCA asks for nothing beyond the download.

What Doctors Know ships an update every 4 months, EDTNA/ERCA every 2 months. The most recent releases landed on October 6, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | What Doctors Know | EDTNA/ERCA |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 2 months** |
| Size | 12 MB | 21 MB |
| Requires iOS | **13.0** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 17+ | 12+ |
| Developer | [PressPad Sp. z o.o.](https://appshunter.io/developer/449000752) | [Trilobite Technologies, s.r.o.](https://appshunter.io/developer/1106306899) |

## What reviewers say

### What Doctors Know

[App page](https://appshunter.io/ios/app/what-doctors-know/id880982965)

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

**In-app purchases (14)**

| Purchase | Price | Billing |
| --- | --- | --- |
| What Doctors Know | $5.99 | per year |
| Issue #1 | $0.99 | one-time |
| Issue #2 | $0.99 | one-time |
| Issue #3 | $0.99 | one-time |
| Issue #95 | $0.99 | one-time |
| Issue #96 | $0.99 | one-time |
| Issue #97 | $0.99 | one-time |
| Issue #98 | $0.99 | one-time |
| Issue #99 | $0.99 | one-time |
| Issue #100 | $0.99 | one-time |
| Issue #91 | $0.99 | one-time |
| Issue #92 | $0.99 | one-time |
| Issue #93 | $0.99 | one-time |
| Issue #94 | $0.99 | one-time |


### EDTNA/ERCA

[App page](https://appshunter.io/ios/app/edtnaerca/id1531289859)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is What Doctors Know free?

What Doctors Know is free to download, with in-app purchases available.

### Is EDTNA/ERCA free?

EDTNA/ERCA is free to download, with no in-app purchases.

### Do What Doctors Know or EDTNA/ERCA have ads?

Neither What Doctors Know nor EDTNA/ERCA shows ads.

### Which is updated more often, What Doctors Know or EDTNA/ERCA?

What Doctors Know ships an update every 4 months, and EDTNA/ERCA every 2 months. Most recently, What Doctors Know was updated on October 6, 2026 and EDTNA/ERCA on October 7, 2026.

---

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