Randori

Randori is a jiu-jitsu training log for iPhone and Apple Watch. Track your heart rate while you roll, note your effort and what caught you, and get film-backed lessons matched to exactly that — then connect with your training partners and watch your belt progress take shape. Your training, finally counted.

What's in the app

• Live sessions on the mat. Heart rate from Apple Watch or a paired chest strap, effort per roll, session timing — the physical truth of a night of training, recorded while it happens.
• Notes in your own words. "Got caught in an armbar from closed guard, couldn't get my elbow back in time" is a real entry. The log speaks jiu-jitsu, not dropdown menus.
• Stop getting caught by the same thing. Randori matches your note to film-backed lessons from instructors worth learning from — the armbar defense, then the counters to the counters. Matched on your iPhone, white belt through black.
• Training partners. Connect with the people you actually roll with, share sessions, and see the gym's rhythm — with reporting and moderation built in from day one, not bolted on.
• Belt progress you can see. Sessions accumulate into an honest forecast of where your training is heading.
• Apple Health, optionally. Sessions write back as workouts with real heart-rate data. Everything works without Health access too.
• Twelve languages at launch, from Japanese to Arabic.

Why the studio built this

Because the founder trains. Every fitness app treats jiu-jitsu as "Other" — a gap between running and rowing where an hour of the hardest training a body can do gets logged as a calorie guess. Randori was built by a practitioner who wanted three things after class: what did tonight cost me, what caught me, and how do I make sure it doesn't catch me again. The app is those three questions, answered properly, and nothing else.

How it was made

SwiftUI on iPhone and Apple Watch, with live workout sessions streaming heart rate from the wrist or a Bluetooth chest strap. Notes are matched to the lesson library on-device. The social layer runs on CloudKit's public database — no accounts, no server of ours — with user reporting wired into the studio's own moderation tooling, so the community stays worth belonging to. Sessions sync through your private iCloud and write to Apple Health as real workouts.

Frequently asked

What does Randori track?

Training sessions: live heart rate from Watch or chest strap, effort per roll, and notes in your own words.

How do the lessons work?

Write what happened and Randori matches it to film-backed lessons — the defense, then the counters to the counters. Matching happens on your iPhone; the library runs white through black belt.

Does it work with training partners?

Yes — connect with the people you roll with, share sessions, and see the gym's rhythm. Reporting and moderation are built in.

Does it connect to Apple Health?

Optionally. Sessions write back as workouts with real heart-rate data; the log works fully without it.

Is Randori available now?

Yes — Randori 1.0 is on the App Store for iPhone, with Apple Watch support for live sessions.