Your Strava run, finally explained
Negative Split adds the deep, honest training analytics that usually sit behind Premium: right on your own Strava activity, profile and training pages. Every number is computed in your browser. Nothing is ever uploaded.
What it adds
Strava shows you the run. Negative Split explains it: across every page you already use.
On each activity
- Negative-split pacing: did you finish faster than you started
- rTSS, Intensity Factor & hill-fair GAP (Minetti)
- Aerobic decoupling (Pa:HR)
- Time in zone + the 80/20 read
- Auto interval detection: each rep listed
- Fitness / Fatigue / Form + injury-risk (ACWR)
Share any run
- A downloadable Run Card: your route, stats & heart-rate zones
- Interval reps as a bar chart, plus a playful one-liner
- Add it as a photo to your Strava activity
- Built in your browser: nothing uploaded, no Strava branding
On your profile
- A clean, sortable personal-best list
- Age-graded PBs: your score vs the age & sex record standard, with class bands
- VDOT: a VO2max estimate from your best race, on Garmin's scale
- Honest 5K–Marathon race predictions
- Pace-duration curve + Critical Velocity
A free Year in Sport
- Totals, sport split, season bests
- A daily-activity heatmap & monthly volume
- Honest fun stats: cheeseburgers burned, Everests climbed, the walk to Mordor
- Your runner archetype on a downloadable holo Year Card
- Built from your own history: nothing uploaded
On your dashboard
- Fitness / Fatigue / Form in your profile card, free
- A form pill: fresh, neutral, productive or overreaching
- Your VDOT & age-grade score, right in the strip
- Kudos confetti when you give kudos: no automation, ever
- An orange outline on activities you already kudoed
When you edit a run
- A suggested title from the detected workout
- A suggested description
- A playful alternative title too, one click to copy
- Copy it if you like it: it never changes your fields
Honest by design
The kind of tool that respects your data: because it never has it.
100% local
Every metric is computed on your device. Your activity data is never uploaded, never sent anywhere.
No login, no subscription
Install and use it. No account, no email, no recurring charge. It's genuinely free.
Transparent math
No official Strava API, no AI on your data. Every number is deterministic, citable sports-science.
One named permission
It reads only your own strava.com pages: never broad, all-websites access.
“Privacy is enforced by architecture rather than by policy, which is the strongest form.”Read the feature: Negative Split, free local Strava running analytics →
Negative Split for Strava
The Premium-grade numbers, free and local: rTSS, GAP, zones, PMC, interval detection, honest race predictions, Critical Velocity and a Year-in-Sport recap. Runner-first, and it never uploads a thing.
- ✓ Free: no login, no subscription
- ✓ 100% in your browser, nothing uploaded
- ✓ Runner-first, transparent, deterministic math
Negative Split is an independent project. It is not affiliated with, endorsed by, or sponsored by Strava, Inc. Strava is a trademark of Strava, Inc.