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4+
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9+
Apps in this category may contain mild or occasional cartoon, fantasy or real-life violence, as well as occasional or mild adult, sexually suggestive or horrifying content and may not be suitable for children under 9 years of age.
12+
Apps in this category may contain occasional mild indecent language, frequent or intense cartoon or real-life violence, minor or occasional adult or sexually suggestive material, and simulated gambling, and may be for children under 12 years of age.
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You must be at least 17 years old to access this App.
Apps in this category may contain frequent and intense offensive language; Frequent and intense cartoon, fantasy or realistic violence: frequent and intense adult, scary and sexually suggestive subjects: as well as sexual content, nudity, tobacco, alcohol and drugs, may not be suitable for children under 17 years of age.

About Protocol66

66 days. 5 habits. Miss a day, start over.

Protocol 66 is the science-backed alternative to extreme fitness challenges. Based on habit formation research — not bro science — it takes exactly 66 days to build lasting habits.

THE RULES ARE SIMPLE
- Pick 5 daily habits
- Complete all 5 every day
- Miss a day, restart from zero
- Rest days are earned, not given

WHY 66 DAYS?
Research by Phillippa Lally at University College London found it takes an average of 66 days to form automatic habits. Not 21. Not 30. Not 75.

THIS ISN'T FOR EVERYONE
No streaks to protect you. No lives. No second chances. If you're looking for an app that goes easy on you, this isn't it.

Ready to commit?

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Privacy Policy: https://www.pocketapps.studio/protocol66/privacy
Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
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What's New in the Latest Version 1.0.1

Last updated on Jan 29, 2026
Old Versions
Version 1.0.1
• Late Logging - Forgot to log yesterday? Now you can catch up before your challenge fails
• Challenge Failed Card - Clear visibility when challenges end with easy restart options
• FAQ Section - Find answers to common questions in Profile
• Better Notifications - Stay on track with evening reminders and milestone celebrations
• Bug fixes and performance improvements for iOS 26
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Version History
1.0.1
Jan 29, 2026
Version 1.0.1
• Late Logging - Forgot to log yesterday? Now you can catch up before your challenge fails
• Challenge Failed Card - Clear visibility when challenges end with easy restart options
• FAQ Section - Find answers to common questions in Profile
• Better Notifications - Stay on track with evening reminders and milestone celebrations
• Bug fixes and performance improvements for iOS 26

Protocol66 FAQ

Click here to learn how to download Protocol66 in restricted country or region.

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