Custom Running Intervals vs Fartlek
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Custom Running Intervals
Create custom running workouts with flexible intervals based on time or distance. Track progress, build training plans, and analyze past runs with detailed results. Your data is private and stored securely on your device or iCloud.
- Configurable time or distance intervals
- Repeatable interval blocks
- Training plan calendar
- Historical run analysis
- Apple Watch monitoring
- iCloud synchronization
- Data privacy
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This is a flexible custom interval timer and training scheduler with historical analysis, and you are the only one who has access to your data! As a runner, I’ve had challenges finding a running timer that can manage my more involved interval combinations. Custom Running Intervals allows you to build variable activities with repeatable blocks of intervals. Intervals can be by time or by distance with 3 intensities - walk, steady, and fast. You can repeat your intervals a specific or indefinite number of times, for a defined amount of time, or for a given distance. With an inexpensive upgrade, you can create as many combinations of repeatable sets in the variations you choose, build a training plan on a calendar, see results of past runs, and export results to other apps. Also, your data is only available to you - even I can’t see it. Your data will only exist on your phone, or in your own iCloud storage if you choose. If you save your data to iCloud (by default), you can view the results on any other iPhone or iPad that shares the same iCloud account. Features: 1. Configurable intervals - distance (miles, kilometers), time (hours, minutes, seconds). 2. Configurable repeat blocks of intervals - # of times (or until stopped), distance, time. 3. Clone activities (use an existing activity - repeats and intervals - as a basis to create a similar activity). 4. Apple Watch monitoring and control and heart rate (iPhone app must be started). 5. Configurable settings. 6. Audio cues by voice, tone, or both (in Settings). 7. Pause, Resume, or Stop an activity, Skip repeat blocks. 8. View current elapsed time, distance, interval progress, overall pace. 9. End an in-progress repeat block (and proceed to the next). 10. Results by interval and repeat block, as well as default distance unit (each mile or kilometer). 11. Results (including steps, time, distance, and pace) available immediately after run. 12. Map view to verify GPS location prior to starting run. 13. Map view of running route in results including markers by mile/kilometer and pauses. 14. Helpful on-screen guide when creating first activity and configuring. 15. Activities and results stored in iCloud for synchronization across devices and data loss prevention. Apple Watch If you have an Apple Watch, you can also start, pause, and stop an activity in progress from the watch. NOTE: the Apple Watch app (included with your iPhone download) communicates with the iPhone app, so the app must be started on both the watch and phone to use the watch app. Apple Watch Features: 1. View existing activity configurations. 2. Start an activity (if iPhone app is started). 3. Pause, Resume, or Stop an activity. 4. View current elapsed time, distance, interval progress, overall pace. 5. End an in-progress repeat block (and proceed to the next). Available Full Features (In App Purchase) 1. Configure an activity with multiple repeat blocks for more complex intervals (standard version allows one repeat block) 2. Add planned training runs on a Training Calendar for a selected custom interval (free version allows up to 5). 3. View and filter a graph of your pace over time for activities (free version allows up to 5 past runs). 4. View the results of your runs on the Training Calendar including a map of the route. weather conditions, elevation, pace, and heart rate. 5. Create repeatable training plans to easily add planned runs to the Training Calendar. 6. Sort your past results by date, total time of run, distance, and pack. 7. Export your results (current or history) in GPX format for importing to other trackers. 8. Fix GPS for anomalies. 9. Import results in GPX format from any tracker app. 10. Track miles run on your pairs of shoes. 11. Manually enter results for a run if you forget to track. 12. Manually edit the time and distance for a run. 13. Share a run with photo to social media and other apps. 14. Track a run on a cruise ship.
Fartlek
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Tell your AI coach your goal and the days you can run, and get a training plan that adapts every week to how your runs go. Need a single workout? Describe it or paste a screenshot, and it's ready in seconds. Then just run: voice and haptic cues guide every interval, even with your screen off. 25 workouts runners actually love — HIIT, fartlek, tempo, hills, Yasso 800s. On iPhone and Apple Watch. Because running the same pace every day only makes you better at running the same pace. Break the plateau. EVERY RUN IS A NEW CHALLENGE Every workout here has a specific goal and a different feel — so you actually train different muscles, systems, and skills instead of just logging miles. Your running workout is fun now :) Speed: 200m pops, ladders, strides, sprint finishers Strength: Hill repeats, power builders, switchbacks Stamina: HIIT, Cruise intervals, tempo waves, Yasso 800s Endurance: Progressive aerobic, negative splits, scenic cruises Fun: Fartlek games, stoplight play, music flow runs Each workout has a warm-up, main set, and cooldown — with clear effort guidance through every phase. AI WORKOUT GENERATOR Tell the AI coach what you want — "30 minutes, hill repeats, moderate" or "a fartlek that doesn't bore me" — and get a runnable workout in seconds. Paste a screenshot of a workout you saw online and we'll convert it into intervals. TRAIN BY EFFORT, NOT NUMBERS Every interval shows a target effort (80% for work, 30% for recovery). No heart rate monitor needed. GPS pace lies anyway — effort just works better. AUTO-LAP BY DISTANCE OR TIME Distance intervals auto-complete when you hit 200m, 400m, 800m, or whatever target you set. Time intervals count down with precision. No fumbling with lap buttons mid-stride. AUDIO & HAPTIC CUES Get notified at interval start, halfway, and end. Works with your screen off, works on Apple Watch. Built for running outside, where you can't keep glancing at a screen. APPLE WATCH COMPANION Run straight from your wrist. Leave your phone behind for track sessions — the Watch app handles everything on its own. CLEAN, GET-OUT-OF-THE-WAY DESIGN Big, glove-friendly controls. Dark mode. One-screen run view with your current interval front and center, and what's next right there too. AFTER YOUR RUN Review every completed interval — distance, time, pace. Auto-syncs to Apple Health. WORKOUT TYPES Tempo: Sustained-effort training Intervals: Structured speed work Fartlek: Mixed-pace playful running Hills: Uphill repeat sessions Long Run: Extended endurance efforts 3 DURATION OPTIONS Quick (10–15 min): Short, sharp sessions Standard (20–35 min): Complete workouts Long (40–60+ min): Extended training WHO IT'S FOR - Runners looking to improve their times - Runners who like variety and fun - Amateur athletes who want to gain leg strength and power - Anyone looking to improve overall fitness and health - Anyone looking to lose weight with HIIT (High-Intensity Interval Training) - Anyone who wants to run intervals without 10 minutes of setup - Anyone tired of complex running apps that feel more like Instagram No social feeds. No data mining. Just running. Terms of use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is update cadence: Fartlek at every 4 days against Custom Running Intervals's every 3 months. Custom Running Intervals's advantage is iOS requirement (16.0 vs 18.5). On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Custom Running Intervals sells 1 one-off in-app purchase and Fartlek sells 3 in-app purchases, starting at $1.99 per 7 days. Whichever you choose, the download price is not the number that matters.
Custom Running Intervals ships an update every 3 months, Fartlek every 4 days. The most recent releases landed on November 3, 2026 and October 30, 2026 respectively.
| Parameter | Custom Running Intervals | Fartlek |
|---|---|---|
| Price | Free | Free |
| Rating | 2.0 (1 ratings) — better | — |
| Positive reviews | 0.0% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Every 3 months | Every 4 days — better |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad, Apple Watch — better | iPhone, Apple Watch |
| Requires iOS | 16.0 — better | 18.5 |
| Further details — not scored | ||
| Size | 11 MB | 29 MB |
| Age rating | 4+ | 4+ |
| Developer | John Mallonee | Axis SA |
In-app purchases
Custom Running Intervals
- Full Capabilities$0.99
Fartlek
- Weekly Plan$1.997 Days
- Monthly premium$4.991 Month
- Yearly Premium3 Days trial$29.991 Year
Questions
Is Custom Running Intervals free?
Is Fartlek free?
Do Custom Running Intervals or Fartlek have ads?
Which is updated more often, Custom Running Intervals or Fartlek?
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