Why I built ZoneTempo

Jeroen PeerbolteFounder of ZoneTempo · amateur runner, aiming at a fast 10K

Too fast, too soon

I build apps the way I started running: with a lot of enthusiasm and very little patience. I wanted to get fast, and I wanted it quickly. So almost every run turned into a hard run.

My legs disagreed. First shin splints, then calf problems. The advice was always the same: run most of your kilometres easy and build up slowly. And it's exactly what I didn't do once I was out the door. In the moment, easy pace feels too slow, and nobody is there to tell you to hold back.

The coach I needed

What I needed was a coach who runs with me: one who says “slow down, you're in zone four” while it still matters, and stays quiet when I'm doing it right. That's ZoneTempo. It speaks your pace and heart-rate zone over your music, so you can stick to the plan without looking at your phone.

If you're the same kind of runner, start with zone 2 running and the zone 2 calculator. They're the guides I wish I'd read first.

Running to the beat

Slowing down wasn't the only fix. Reading up on my shin splints, I kept coming across the same advice: take slightly shorter, quicker steps. A higher running cadence means lighter landings and less load on your legs with every step.

Counting steps mid-run doesn't work, so I ran to premixed music at a tempo that felt comfortable, and let my feet follow the beat. It helped. But finding a mix at exactly the right BPM, run after run, was a hunt.

That's why I added Beatmatch to ZoneTempo: continuous mixes at your own cadence, so every step lands on the beat, with the coach timing its cues around the drops instead of over them.

Built around WHOOP

I've worn a WHOOP strap every day since 5 December 2024. It's great at telling you how hard you went, afterwards. On the run it has no screen and no voice. ZoneTempo reads the strap's live heart rate through Heart Rate Broadcast and turns it into cues you can hear.

How ZoneTempo is made

• ZoneTempo is a small, independent product by Breach Ventures B.V. in the Netherlands. It is not affiliated with WHOOP.
• The pace and distance accuracy numbers on this site come from simulations with realistic GPS noise.
• The guides follow widely used training guidelines. They are general information, not medical advice. If something hurts, see a professional. I learned that the hard way.

Say hi

Questions, ideas or a bug: hello@zonetempo.com. Follow the build on InstagramTikTok.

ZoneTempo is an independent app. It is not affiliated with, endorsed by or sponsored by WHOOP, Inc. WHOOP is a trademark of WHOOP, Inc.