Timer Sync now available for testers

A wonderful year with Flow

The past year has been an incredible journey for us with Flow. Every day, we receive heartwarming messages from users, sharing how Flow has positively impacted their lives. Knowing the difference Flow makes is both humbling and inspiring—it's the driving force behind our passion and dedication to improving Flow every single day. We're so grateful for your continued support and kindness, which mean the world to us. Thank you for being part of our journey!

Introducing Flow 4.0 across all platforms

Flow 4.0 introduces a unified version number across iOS, macOS, visionOS, and watchOS. Previously, each platform had its own versioning system due to the staggered platform-support of Flow over the past six years, starting the journey with macOS back in late 2018. 

With the introduction of Timer Sync, we feel this is the perfect moment to unify the version numbers. This change simplifies tracking and consistency across platforms.

What's new in Flow 4.0

Version 4.0 isn't just about syncing timers; it contains a bunch of new features, improvements, and refinements, most notably, fully redesigned settings: We've revamped the settings interface to align with the native design language of iOS and to maintain consistency across all Flow platforms. This continues the redesign efforts we began on Mac and Vision a few months ago.

We've also improved our project's widget configuration to enhance reliability and flexibility, utilizing the latest Swift features. Note: Due to this refactoring, you'll need to re-add any existing widgets to your lock screen or home screen after updating.

Real-time Timer Sync: Seamless and privacy-focused

A real-time sync of the Flow timer across Mac and iPhone has been a long-standing goal for Flow. Our aim has always been to make it fast, seamless, and user-friendly, all without requiring users to create an account.

While iCloud was a natural starting point—as it's already used for syncing the statistics and comes integrated with the device—we quickly discovered it wasn't suitable for real-time syncing due to latency issues. Timers involve frequent state changes, and we wanted these interactions to feel instantaneous.

To achieve this, we implemented a hybrid approach. iCloud is used to group devices belonging to the same user, while Firebase powers the real-time syncing of the timer. The result is a seamless, intuitive, privacy-focused experience that doesn't require users to sign up, create an account and share their personal data.

How to use the timer sync

After joining the beta testing group and installing Flow 4.0, you'll find a new setting called "Timer Sync" in the app. Enabling this feature synchronizes your timer and session settings—such as durations, cycle, and auto-start options—across all your devices signed in with the same iCloud account. To ensure everything works smoothly, update Flow on all your devices to Flow 4.0, enable Timer Sync on each, and confirm you're signed in with the same iCloud account.

Currently, Timer Sync is available on iOS, iPadOS, and macOS. With iOS 18 and watchOS 11, the Live Activity displaying the Flow timer already appears on your Apple Watch. Full integration with the Flow app on Apple Watch is planned for a future update.

Your statistics are synchronized automatically and independently of this setting via iCloud.

Join the beta and share your feedback

Flow 4.0 is available now on TestFlight, and we'd love for you to try it out. As a beta version, some bugs are expected, but your feedback will help us polish the experience. If you're interested, send us an email with your full name and Apple ID to support@flow.app. We'll then add you to the list and you'll receive an invite to TestFlight from Apple. Let us know what you think!

Have a wonderful 2025!

Thank you so much for taking the time to read today's devblog! We wish you a wonderful new year and look forward to seeing you in our next post.

And as always, if you enjoy using Flow and want to support its development, we'd be grateful for a review on the App Store. Every review is important and helps our tiny developer studio tremendously.

We appreciate you all very much. Cheers!