About
Intervals.icu is a comprehensive, free training platform trusted by over 160,000 active athletes, with more than 193 million activities analyzed since 2018. Designed by athletes for athletes, it covers every stage of training: tracking progress, analyzing performance, and planning future sessions. The platform's analytics engine offers the classic Performance Management Chart (PMC) for long-term fitness tracking, automatic eFTP estimation, power curves with watts-per-kilogram comparisons across seasons, and cardiac drift analysis for aerobic efficiency. Multi-sport support means separate zones and metrics are maintained for cycling, running, swimming, rowing, and more. For planning, Intervals.icu provides a drag-and-drop training calendar, a full-featured structured workout builder (supporting ZWO, FIT, MRC, and ERG formats), and custom training zones anchored to FTP, LTHR, or user-defined fields. Workouts can be synced directly to devices and third-party platforms. Coaches benefit from athlete management tools, in-app messaging, group chats, and the ability to tag and organize athlete rosters. An open REST API and webhook system allow developers to build custom integrations, upload and download activities, and manage wellness data programmatically. With deep integrations across Garmin, Polar, Suunto, Coros, Wahoo, Strava, Zwift, Oura, WHOOP, HUAWEI Health, and 250+ more platforms, Intervals.icu slots seamlessly into any athlete's existing ecosystem — all without a subscription fee.
Key Features
- Performance Management Chart & eFTP: Track long-term fitness, fatigue, and form with the classic PMC. Automatic eFTP estimation from maximal efforts keeps training zones current without manual input.
- Advanced Activity Analysis: Deep-dive into every ride, run, or swim with automatic interval detection, power curve histograms, Coggan and proprietary metrics, and aerobic decoupling (cardiac drift) analysis.
- Structured Workout Builder & Training Calendar: Build workouts targeting power, HR, pace, or cadence. Schedule them in a drag-and-drop calendar with device sync and support for ZWO, FIT, MRC, and ERG file formats.
- Coaching & Team Communication: Manage athlete rosters, send group messages, share workouts and screenshots, and connect athletes with professional coaches — all within the platform.
- Open REST API & 250+ Integrations: A full REST API with webhooks enables custom integrations for developers. Native connections span Garmin, Strava, Zwift, Polar, Coros, Wahoo, Oura, WHOOP, and hundreds more.
Use Cases
- A competitive cyclist downloads years of Strava and Garmin history to visualize long-term fitness trends using the Performance Management Chart and eFTP progression.
- A triathlon coach manages a roster of 20 athletes, assigns structured workouts, reviews their power and pace data, and communicates training feedback all within a single platform.
- A recreational runner uses the training calendar and workout builder to follow a structured marathon plan, syncing sessions directly to their Garmin watch.
- A developer builds a custom dashboard by querying the Intervals.icu REST API to pull wellness and performance data into a personalized analytics tool.
- A data-driven cyclist uses power curve analysis and cardiac decoupling metrics across multiple seasons to identify weaknesses and track aerobic fitness improvements over time.
Pros
- Completely free to use: Intervals.icu offers its full suite of analytics, planning, and coaching tools at no cost, making professional-grade training analysis accessible to all athletes.
- Exceptionally broad integrations: With 250+ connected platforms and devices, athletes can automatically sync data from virtually any wearable, GPS device, or training app they already use.
- Multisport and multi-metric support: Independent zones and metrics per sport ensure accurate analysis whether the athlete is a pure cyclist, runner, triathlete, or rows and swims as well.
- Developer-friendly open API: A full REST API and webhook system let technically inclined athletes and third-party developers build custom dashboards, automations, and integrations on top of the platform.
Cons
- Steep learning curve for new users: The breadth of metrics, charts, and settings can be overwhelming for beginner athletes unfamiliar with training science concepts like TSS, eFTP, or PMC.
- Web-only interface: Intervals.icu is primarily a web application with no dedicated native mobile app, which can limit on-the-go usability compared to mobile-first competitors.
- Community-driven support: As a platform built and maintained by a small team, support is largely community-forum-based rather than offering dedicated customer service channels.
Frequently Asked Questions
Is Intervals.icu really free?
Yes. Intervals.icu is free to use for all athletes. There is no subscription fee or paywall on core features. The platform has been free since it launched in 2018.
Which devices and platforms does Intervals.icu integrate with?
Intervals.icu integrates with 250+ platforms including Garmin, Strava, Zwift, Wahoo, Polar, Suunto, Coros, Oura, WHOOP, Amazfit, HUAWEI Health, MyWhoosh, Rouvy, and many more.
Can coaches use Intervals.icu to manage multiple athletes?
Yes. Intervals.icu includes athlete management tools that allow coaches to follow, tag, and organize athletes, share workouts, review activity data, and communicate via group messaging.
What sports are supported beyond cycling?
Intervals.icu supports cycling, running, swimming, rowing, and other sports. Each discipline has its own independent zones, settings, and appropriate metrics for accurate multi-sport tracking.
Does Intervals.icu have an API for developers?
Yes. Intervals.icu provides a full open REST API with webhook support, enabling developers to upload and download activities, manage wellness data, create workouts, and build custom integrations.
