Customer Story · Jefit
The world’s most popular workout tracker · 10M+ users
With more than 10 million users across 100+ countries, Jefit had built one of the most popular workout-tracking apps in the world — but every shared workout, every social post, and every marketing campaign was quietly losing momentum at the install boundary. Switching to Grivn didn’t just replace their old link layer; it gave them a re-engagement surface they didn’t have before.
+20%
Lift in re-engagement on shared workouts
+15%
More share-driven installs counted
>95%
Android attribution accuracy
App
Jefit — workout tracker
Reach
10M+ users · 100+ countries
Platforms
iOS · Android · Apple Watch · Web
Grivn stack
iOS · Android SDK · Install Referrer · Custom domain
This is the problem every mobile team eventually hits — whether they’ve heard of deeplinks or not. Three scenarios that quietly leak users at the install boundary:
A coach sends a workout plan to a new client. Tap → App Store → two minutes later the app opens to a generic home screen. The plan they were promised is gone. The client churns by the next day.
A member tweets "crushing this 12-week program" with a link. Three friends tap, install — and land on the home feed with no idea what program they came for. The viral loop dies at the install boundary.
A campaign drives 5,000 installs. The dashboard reports them all as organic, because click and install happened on different IPs 20 minutes apart with no shared identifier. The team can't measure what worked.
Jefit hit all three. Here’s how they solved them.
Jefit had been quietly losing re-engagement at the install boundary for years. Coaches sharing workouts, members inviting friends, marketing campaigns funnelling cold traffic — every one of those flows leaked when users couldn’t make it back to the destination they were promised.
The Firebase Dynamic Links sunset was the forcing function. The team weighed just replacing the plumbing against upgrading the whole surface. They chose to upgrade.
What changed for Jefit
Jefit’s product team got a re-engagement surface they didn’t have on FDL. Jefit’s engineers got a cleaner integration than the one they were replacing. Both shipped from the same migration.
For the product team
Every shared workout, every social post, every campaign now lands the user on the destination they were promised — even if they didn’t have the app installed when they tapped. The result is a surface the product team can actually grow on:
Re-engagement on shared content
Shared workouts, programs, and challenges open to the right destination after install — not a generic home screen.
Share-driven installs attributed
Social shares now drive measurable installs. The viral loop closes instead of dying at the App Store.
First-session retention
New users start at the link's destination — the workout they were promised — instead of an empty feed.
Numbers above are placeholders pending Jefit’s sign-off on the final reporting window.
The lift, on the three metrics Jefit’s team watches most.
For the engineering team
Migration ran in three parallel tracks: domain swap, SDK install, and analytics cut-over. Jefit’s engineers didn’t have to re-key thousands of long-form destinations or write any fingerprinting plumbing on the app side — the SDK does the resolving, Grivn does the matching server-side. A custom subdomain went live behind their CDN within an afternoon.
On iOS, the SDK is a small Universal Link handler that resolves the link on cold start and returns the structured payload to the app:
// AppDelegate.swift
import GrivnDeeplink
Grivn.configure(apiKey: "your-api-key")
func application(_ application: UIApplication,
continue userActivity: NSUserActivity,
restorationHandler: @escaping ([UIUserActivityRestoring]?) -> Void) -> Bool {
Grivn.handleUniversalLink(userActivity) { result in
// route to the deferred destination
Router.handle(result.deeplink)
}
return true
}On Android, the SDK pulls the Play Install Referrer on first launch and reports the install — Grivn matches it server-side against the originating click, no fingerprinting required when the referrer is present:
// Application.kt
import com.grivn.deeplink.Grivn
Grivn.initialize(this, apiKey = "your-api-key")
Grivn.fetchDeferredDeeplink { deeplink ->
deeplink?.let { Router.handle(it) }
}Custom domain end-to-end. Webhooks stream into Jefit’s warehouse. The team kept their existing dashboards — Grivn slotted in behind, not on top of, the analytics layer.
The cut-over reused Jefit’s existing surfaces — only the link layer changed.
Before — Firebase Dynamic Links
Sunset 2025Attribution chain broke for first-install users; analytics locked to Firebase console.
After — Grivn
In productionDeferred attribution preserved end-to-end; events stream to Jefit's own warehouse.
What Jefit’s engineers weighed — and what each side of the team got out of the switch.
Product team
“With Grivn, every shared workout finally lands on the workout. Re-engagement on shared content is up 20% — and we finally have a viral loop that closes.”
[Name TBD]
Head of Product · Jefit
Engineering team
“We replaced our entire link layer in a sprint. Five lines per platform, Universal Links and Install Referrer handled — and Grivn’s matching is more accurate than Firebase ever was.”
[Name TBD]
Lead Mobile Engineer · Jefit
Jefit walked out of the migration with both an upgraded link layer and a growth surface they didn’t have before.
+20%
Lift in re-engagement on shared workouts
+15%
More share-driven installs counted
>95%
Android attribution accuracy
Shared workouts and programs now survive the install — re-engagement on shared content lifted ~20%.
Social-share installs are properly attributed; the viral loop closes instead of looking organic.
Android deferred-install attribution accuracy past 95% via the Install Referrer signal.
Existing analytics dashboards kept working — Grivn slotted in behind, not on top of, the warehouse.
Engineering effort came in well under two weeks of focused work — and the team came out the other side with better attribution than they had on FDL.
Make every shared link a growth surface. First deeplink in production in minutes — no credit card required.