# O2CO2 — Guided Breathing > Guided breathing exercises for relaxation, stress management, and improved well-being. (iPhone/iPad app by Les Entrecodeurs.) - Source: https://appshunter.io/ios/app/o2co2/id1671497009 (this page in markdown: same URL + `.md`) - Developer: [Les Entrecodeurs](https://appshunter.io/developer/1671497011) - Category: Health & Fitness, Medical - Price: Free - Rating: 5.00/5 from 1 App Store ratings · 9 written reviews indexed - Age rating: 4+ - Requires: iOS 15.1 · 332 MB - Languages: English - Released: 2023-03-15 - Data updated: 2026-06-15 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/o2co2/id1671497009/reviews.md ## What is O2CO2? Welcome to O2CO2 - your personal breathing companion! This FREE application is designed to help you relax, manage your stress, and improve your health through two well-known breathing techniques : Guided Breathing (inspired by pranayama, yoga, meditation techniques, and a method used by a world-famous instructor known for his resistance to cold) and Heart Coherence, aka Cardiac Coherence. Our application will allow you to discover the benefits of deep breathing and oxygenating your body, as well as improve your concentration and mental clarity. The Guided Breathing exercises in the application are easy to follow and suitable for all levels of experience, whether you are a beginner or an experienced practitioner. This technique of deep and rapid breathing followed by a period of breath retention helps improve health, resilience to stress, ability to handle extreme temperatures, as well as providing more energy and better performance in sports. Heart Coherence refers to a breathing technique that helps synchronize breathing with heart rate in order to promote relaxation and reduce stress. By using our application regularly, you can : Reduce stress and anxiety Improve your sleep quality Increase your energy and concentration Strengthen your immune system Reduce inflammations Improve your overall well-being So, download O2CO2 for free now and begin your breathing journey to a healthier, more balanced life ! ## Key features - Guided Breathing exercises - Heart Coherence technique - Stress and anxiety reduction - Improved sleep quality - Increased energy and concentration - Enhanced immune system ## Recent user reviews (9 of 9) All indexed reviews: https://appshunter.io/ios/app/o2co2/id1671497009/reviews.md ### 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. ## Frequently asked questions about O2CO2 ### What breathing techniques does O2CO2 offer? O2CO2 offers two primary breathing techniques: Guided Breathing, inspired by pranayama and meditation, and Heart Coherence, which synchronizes breathing with heart rate for relaxation. ### Can beginners use O2CO2? Yes, the Guided Breathing exercises are designed to be easy to follow and suitable for all levels of experience, from beginners to experienced practitioners. ### What are the main benefits of using O2CO2? Regular use of O2CO2 can help reduce stress and anxiety, improve sleep quality, increase energy and concentration, strengthen the immune system, and reduce inflammation. ### Is O2CO2 free to use? Yes, O2CO2 is a free application and does not require any payment to access its features. ### Does O2CO2 have ads? No, O2CO2 is ad-free, providing an uninterrupted experience for users focused on relaxation and well-being. ### What devices is O2CO2 available on? O2CO2 is currently supported on iPhone and iPod devices. ### How often is O2CO2 updated? The latest version of O2CO2 is 1.2, and it was last updated on June 16, 2025. Updates aim to improve functionality and user experience. ### What is the age rating for O2CO2? O2CO2 has an age rating of 4+, making it suitable for a wide range of users. ## Version history (last 3 releases) ### 1.2 — 2025-06-16 Libraries update ### 1.1 — 2023-03-22 Fixed a bug in the translations of the "Before you start" instructions ### 1.0 — 2023-03-15 No release notes. ## Apps similar to O2CO2 | App | Rating | Price | Category | | --- | --- | --- | --- | | [ApothekenApp Wuppertal / Gevelsberg](https://appshunter.io/ios/app/apothekenapp-wuppertal-gevelsberg/id525405860) | — | Free | Health & Fitness | | [Kid Care - from SLCH](https://appshunter.io/ios/app/kid-care-from-slch/id377701960) | 4.8 (25) | Free | Health & Fitness | | [Withings](https://appshunter.io/ios/app/withings/id542701020) | 4.6 (353,825) | Free | Health & Fitness | | [Breathe now. 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