I built Intrvl to solve a real training gap: most lifters under-rest and lose performance. Intrvl keeps timing brutally honest so you can lift heavier, hit volume targets, and recover like a pro—without accounts, ads, or cloud dependency.
Timers stay accurate when backgrounded. Lock Screen and Dynamic Island keep rest visible so you never miss the go-again.
Built around 2–3 minute hypertrophy rests and 3–5+ for strength. Precision timers help you hit the window every set.
Quick presets, custom intervals, haptics, and alerts that cut friction—so you focus on output, not fiddling with your phone.
Under-resting kills load and volume. Intrvl enforces honest rest so you can drive strength and growth without guesswork.
Accurate timers that survive backgrounding, Live Activities, clean alerts, quick presets, and zero distractions.
No accounts, no ads, no data collection. Everything runs locally on your iPhone and works fully offline.
I've been lifting seriously since my early twenties, progressing from beginner linear periodisation through intermediate programming blocks built around volume accumulation and progressive overload. Like most people who train long enough, I started caring deeply about the details — not just adding weight to the bar, but understanding why certain training decisions produce results and others stall progress.
The app-switching problem was a constant frustration. I'd be mid-session with a separate rest timer, a separate tracking app, and a training log — and none of them talked to each other. I'd miss rest periods because my timer was buried behind the tracking app. I'd log sets inconsistently because the friction of switching between tools made it easy to skip. The tools available were either too simple (basic stopwatch) or too bloated (subscription apps with social features and coaching videos I'd never use).
I started building Intrvl in 2024 after years of working as an iOS developer. The goal was a single interface that counted down your rest period and let you log your sets without switching apps — precision timing integrated with weight tracking, designed around how serious lifters actually work.
Intrvl's analytics are built on a simple premise: not all volume is equal. A warm-up set at 50% of working weight doesn't generate the same training stress as a working set taken near failure. Counting all sets equally produces volume numbers that look good but don't reflect reality.
Effective Volume excludes warm-up sets from calculations entirely. Strain Score weights exercises by muscle group size — compound movements that load large muscle groups cost more than isolation work — and applies a 1.5× multiplier to failure sets to account for additional recovery cost. These aren't arbitrary design decisions; they're adaptations of established sports science frameworks used in professional athletic monitoring, brought down to the level of individual training sessions.
All calculations run on-device. Your data never leaves your iPhone unless you explicitly choose to share it. iCloud sync, when enabled, is Apple-managed — Intrvl has no access to synced data. This isn't a compromise made for technical reasons. It's the correct way to handle personal health data.
Intrvl launched on the App Store in 2025. It's a one-time purchase ($24.99 USD) with a 14-day free trial. No subscriptions. No premium tiers. Every feature — including the full analytics suite — is included from day one.
The app is built for intermediate to advanced lifters who already understand training fundamentals and don't need a coach explaining form in every session. It's not trying to be a beginner-friendly all-in-one fitness platform. It's a precision instrument for people who take training seriously.
Version 2.7 added coach data export, the web-based Program Builder, custom exercise export, and a recalibrated Strain Score. Development is ongoing. Feature requests go directly to info@intrvl.app.
Want to collaborate, review the timing engine, or request a feature? Reach out.
