# O2CO2 — user reviews

> 9 indexed App Store user reviews of O2CO2 by Les Entrecodeurs, rated 5.00/5 from 1 ratings.

- Source: https://appshunter.io/ios/app/o2co2/id1671497009/reviews
- App overview in markdown: https://appshunter.io/ios/app/o2co2/id1671497009.md
- Rating breakdown: 5★ 1 · 4★ 0 · 3★ 0 · 2★ 0 · 1★ 0

## Most critical reviews (9 lowest-rated)

### 5/5 — Thank you!

*2025-12-29*

Wish I could give six stars! Thank you for this app! Absolutely love the audio with my iPods during the guided breathing and the cardiac boxed breathing for relaxation, balanced and energizing! Amazing app!!!

### 5/5 — Love it

*2024-03-30, version 1.1*

I love this app. It instantly became part of my daily routine.

### 5/5 — Excellent!

*2024-01-15*

Would like however a bit more info on the ‘heart exercise’ …

### 5/5 — Exploring the benefits of practicing cardiac coherence breathing for stress reduction

*2023-05-30, version 1.1*

This app is a total game-changer! It's super easy to use and offers different breathing techniques like dynamic breathing (wim hof like breathing ) and cardiac coherence. The best part? It won't cost you a dime! Get ready to feel so relaxed and improve your well-being with this must-have app

### 5/5 — Daily using

*2023-05-25, version 1.1*

I ve switched from other paid app to o2co2. It’s easy, clear and… free!

### 5/5 — The best breathing app

*2023-05-02, version 1.1*

This is a great breathing app! Love the guidance! Really helpful to track retention times and practice Thank you!!

### 5/5 — Fantastic App

*2023-04-23, version 1.1*

Whm app was to expensive for me ! Thanks to o2co2 Iam able  do my breathing exercise again. The guided breathing is great and easy to use. Works perfectly for me. 
SO HAPPY !!

### 5/5 — Flexible

*2023-04-11, version 1.1*

Nous apprécions la flexibilité, pouvant ajuster le nombre de loop et de respiration par loop, nous pouvons faire la respiration guidée selon notre disponibilité.

Nous aimons le « double tap » après l’apnée car nous pouvons passer à la ronde suivante sans ouvrir les yeux et d’avoir les résultats de l’apnée à la fin de la séance.

### 5/5 — Simple and easy to use

*2023-04-03*

Great app, especially considering it’s free.  The controls are easy to change.  I really like that I have the option to do more energizing breathing protocols or coherence exercises.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-15.*