Intervals Pro grows up: a 14-day trial, a real price, and a coach in WhatsApp

For a while now Intervals Pro has been running as an open experiment: a free AI coach sitting on top of your Intervals.icu data, there to plan, analyse, and talk through your training. Enough of you have used it, leaned on it, and told us where it was wrong that the question is no longer whether an AI coach can be genuinely useful. It can. The experiment worked. This post is about what that means for how the product is offered from here.

We are retiring the perpetual free tier. New athletes start with a 14-day trial, no card required, and then continue on Pro at £19.99 a month. If you are already subscribed, none of this touches you: you keep the price you signed up on. That grandfathering is deliberate and permanent, not a launch promotion. You backed the product early, and early support should mean something.

Why the price is what it is

There are two honest costs behind Intervals Pro, and neither of them goes away.

The first is the AI itself. This is not a static app that ships once and runs for free. Every time the coach reads your recent training, weighs your readiness, reshapes a plan, or answers a question, it is doing real reasoning over your actual data, and that reasoning has a cost that recurs for every athlete, every week they train. A free tier that does this properly for everyone, forever, was never going to be sustainable. Pretending otherwise would have meant quietly making the coach cheaper and dumber over time, which is the opposite of what we want to build.

The second is the work. Over the last stretch we have rebuilt the parts of the system that matter most: how workouts are validated before they reach your calendar, how the coach grounds its advice in your real history instead of assumptions, how it holds the line on readiness and safety, and how it stops itself from confidently telling you something that is not true. That is slow, careful, unglamorous engineering, and it is ongoing. A real price is what lets us keep doing it at the standard the coaching deserves, rather than treating it as a side project that has to pay for itself in attention.

So £19.99 is not us discovering we can charge more. It is us being straight about what a serious, always-on coach costs to run and to keep improving, now that we know it is worth running.

The coach where you already are: WhatsApp

The best coach in the world is useless if reaching it is a chore. So we brought Intervals Pro to WhatsApp.

You can now talk to your coach the way you would text a training partner. Ask how today's session should go, get your morning check-in, adjust the week after a rough night's sleep, all in the app that is already on your phone and already open. There is nothing new to learn and nothing new to remember to check. Onboarding is a conversation, not a setup wizard. For a lot of athletes this is the difference between a coach they consult now and then and one that is actually part of the training week.

Opting in is your choice, and opting out is a single message. The coach only ever sees what it needs to help you.

Install it, and let it reach you

If you prefer the full app, Intervals Pro installs straight to your phone's home screen as a proper app, no app store required.

• On iPhone or iPad: open intervals.pro/chat in Safari, tap the Share button, then choose Add to Home Screen.
• On Android: open it in Chrome and tap Install when the app offers it, or use the browser menu's Install app option.

Once it is on your home screen it launches full-screen like any other app. From Settings → Notifications you can turn on push notifications, so your daily check-in and the nudges that actually matter reach you without you having to go looking. It is quiet by design: the point is to be useful at the right moment, not to buzz for its own sake.

What happens next

When the billing change goes live, existing free users will see the 14-day trial and the upgrade path inside the app. Nothing is required from you before then. If you are already Pro, nothing changes, including your price.

If you have used Intervals Pro for free up to now: thank you. You were here while it was still figuring out what it was, and your training, your questions, and your corrections are a real part of why it works. This next step is simply us committing to it properly, so the coach can keep getting better at understanding the training you are actually doing.