You don't have to pay to start CBT-I (Cognitive Behavioral Therapy for Insomnia) on your phone.
The Rest App, which is based on the principles of CBT-I, has a genuine free tier: keep a nightly sleep log, work through the full educational content, and use the sleep tools, all without paying. Only the AI coach and daily check-ins need a subscription. The free version is a real starting point, not a locked demo. It's only available for iOS at the moment.
The other well-known free option comes from the U.S. Department of Veterans Affairs (VA), and it's open to anyone, not just veterans. CBT-i Coach is a companion app meant to support work you're doing with a provider, while Insomnia Coach is a five-week self-guided plan you can follow on your own. Both include a sleep diary, education, and tools built on the same method.
The trade-off with the free routes is that they don't adapt to you: everyone gets the same plan. But if you want to try the approach before spending anything, they're a smart place to begin.
Full guide: The Best CBT-I Apps (2026).