The training analysis, free and local
Negative Split is a free, 100% local Chrome extension that adds deep training analytics to your own Strava pages: rTSS, hill-fair GAP, zones, honest race predictions, age-graded PBs, VDOT, Critical Velocity and a free Year-in-Sport recap. It adds the training-analysis piece that Strava Premium gates or shows opaquely. It does not replace segments, routes or safety features, use Strava for those, and it works on a free Strava account.
Negative Split vs. Strava Premium
Just the training-analysis piece. Negative Split gives you transparent, deterministic numbers for free, computed locally. Strava Premium is a paid subscription that is much broader than analytics.
| Negative Split | Strava Premium | |
|---|---|---|
| Price | Free | Paid subscription |
| Training analytics | Transparent, deterministic sports-science, shown in full | Fitness & Freshness is HR-based and somewhat opaque; deeper analysis is gated behind the subscription |
| Runs locally / nothing uploaded | Yes, everything is computed in your browser | Computed on Strava's servers |
| Honest race predictions | Yes, 5K–Marathon from your own PBs | Not a core Premium feature |
| Pace-duration curve + Critical Velocity | Yes | Not offered |
| Age-graded PBs (WMA 2025 tables) | Yes, with class bands | Not offered |
| VDOT (VO2max estimate) | Yes, Daniels method | Not offered |
| Year-in-Sport recap | Free, built from your own history | Strava paywalled its recap |
| Auto interval detection | Yes, each rep detected and listed | Not offered |
| Segments / routes / safety features | No, use Strava for those | Yes |
Strava's exact Premium features and pricing are set by Strava and may change, check strava.com for current details. Negative Split is a complement to Strava, not a replacement for it.
Why add it
If all you want is honest, readable training analysis, you shouldn't have to subscribe for it.
- ✓Transparent math. Every metric is deterministic, citable sports-science: rTSS, GAP (Minetti), aerobic decoupling, PMC and ACWR. No opaque HR-only score, no AI on your data.
- ✓Genuinely free. No subscription, no login, no email. Install it and the analysis is there, including a free Year-in-Sport recap.
- ✓100% local. Every number is computed in your browser on your own Strava pages. Nothing is uploaded, one named permission (strava.com), no official Strava API.
- ✓Complements a free Strava account. Keep Strava for segments, routes and safety features. Negative Split just adds the training-analysis layer on top, on a free account.
Negative Split for Strava
A free alternative for the training-analysis piece of Strava Premium: rTSS, GAP, zones, PMC, auto interval detection, honest race predictions, Critical Velocity and a free Year-in-Sport recap. Runner-first, transparent, and it never uploads a thing. Learn more on the Negative Split landing page.
- ✓ Free, no login, no subscription
- ✓ 100% in your browser, nothing uploaded
- ✓ A complement to Strava, not a replacement
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.