Protocol66

Pocket Apps Studio Pte. Ltd. Productivity iPhoneiPadiPod touch

Protocol66 is a free Productivity app for iPhone and iPad by Pocket Apps Studio Pte. Ltd. Requires iOS 18.0. Updated January 29, 2026.

Price: Free; on the App Store
Size: 35 MB; Age 12+
Updated: Jan 29; 2026 · v1.0.1

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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? -------------------------------------------------------------------------------- Privacy Policy: https://www.pocketapps.studio/protocol66/privacy Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

What’s new

Version 1.0.1 · Updated January 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

App privacy

The developer, Pocket Apps Studio Pte. Ltd., reported these privacy practices to Apple.

Data Linked to You

The following data, which may be collected and linked to your identity, may be used for the following purposes:

Contact Info: Email Address

Used for: App Functionality

Data Not Linked to You

The following data, which may be collected but is not linked to your identity, may be used for the following purposes:

Contact Info: Name
Usage Data: Product Interaction
Diagnostics: Crash Data, Performance Data
Identifiers: User ID

Used for: Analytics, App Functionality

App details

Protocol66 is a free Productivity app for iPhone, iPad and iPod touch, developed by Pocket Apps Studio Pte. Ltd. It requires iOS 18.0 or later and is 35 MB to download. It was first released on January 12, 2026 and last updated on January 29, 2026.

Category: Productivity
Price: Free
Version: 1.0.1
Size: 35 MB
Requires: iOS 18.0 or later
Compatibility: iPhone, iPad, iPod touch
Age rating: 12+
Released: January 12, 2026
Last updated: January 29, 2026
Developer: Pocket Apps Studio Pte. Ltd.

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Alternatives to Protocol66

Looking for apps like Protocol66? Here are 6 similar apps on the App Store. The highest rated is Habit Tracker: 66-DayChallenge (5.0/5), and all 6 are free to download.

Protocol66 vs. alternatives
App	Rating	Price	Last updated	Compare
Protocol66	–	Free	January 29, 2026
Routine Builder: Daily Planner	–	Free	Aug 17, 2026	Compare
JetSolutions4u	–	Free	Aug 14, 2025	Compare
Habit Tracker - HabitFinch	–	Free	Jan 25, 2025	Compare
GoodHabits: 66-Day Tracker	–	Free	Aug 17, 2026	Compare
Habit Tracker: 66-DayChallenge	5.0 / 5 (1)	Free	Jun 8, 2026	Compare
ThinkFit Productivity, Fitness	–	Free	Dec 6, 2024	Compare

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