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Proofline

Product · Smart links

One link per creator. The right button for every app it opens in.

Most creator traffic opens inside TikTok and Instagram, where deep links are least reliable. The landing page detects the browser and leads with the method that works there.

What visitors see

Fast, plain, and honest about the commission.

Instagram browser

stretchly.proofline.link/sarah

Sarah Lee

uses Stretchly every morning

Stretchly · Health & Fitness

20% off for 3 months

Claim 20% off on the App Store

  • Already have the app? Open it
  • Copy code SARAH20

Sarah earns a commission.

Opened inside Instagram on iOS

TikTok browser

go.stretchly.app/sarah

Sarah Lee

uses Stretchly every morning

Stretchly · Health & Fitness

20% off for 3 months

Claim 20% off on the App Store

  • Already have the app? Open it
  • Copy code SARAH20

Sarah earns a commission.

Opened inside TikTok on iOS · custom link domain
  • Under 30 KB. Server-rendered, no framework JavaScript, system fonts.
  • One primary button, chosen for the environment; secondary actions sit below.
  • Disclosure built in: “Sarah earns a commission.” A preview image per creator for DMs and posts.

Routing table

Where the link opens decides what it does.

Primary action and best tier by environment
Where it opensPrimary actionSecondaryBest tier
iOS · TikTok in-app browserApple offer-code redemption link“Already have the app? Open it” (universal link, on a real tap)VVerifiedV1 · Apple offer code
iOS · Instagram in-app browserApple offer-code redemption link“Already have the app? Open it” (universal link, on a real tap)VVerifiedV1 · Apple offer code
iOS · link in a YouTube descriptionApple offer-code redemption linkCode spoken in the video, typed into your paywallVVerifiedV1 · Apple offer code (or U1 if typed)
iOS · Safari or ChromeApple offer-code redemption linkApp Clip card or Smart App Banner, if your app has an App ClipVVerifiedV1 · Apple offer code (D4 with an App Clip)
Android · any browser or in-app browserPlay Store with the click ID in the install referrerApp Link, if the app is already installedDDeterministicD2 · Play Install Referrer
Desktop browserQR code to the same link“Text me the link” or “Email me the link”VVerifiedSame as phone (plus D5 post-install link)
Spoken code (podcast, video, live)In-app code entry“How did you hear about us?” for reporting onlyUUser-assertedU1 · code typed in the app (V1 if redeemed in the App Store)

Try it

Pick a source.

Where does the tap happen?
Landing pageiOS · TikTok in-app browser

Sarah Lee recommends Stretchly

20% off for 3 months

Primary button: Claim 20% off on the App Store

  • “Already have the app? Open it” (universal link, on a real tap)
  • Fallback: “Copy code SARAH20” (on tap), then the creator’s custom product page

Sarah earns a commission.

Method that fires
Apple offer-code redemption link
Best tier
VVerifiedV1 · Apple offer code

Universal links rarely open apps from in-app browsers, but App Store links do. So the purchase happens in the App Store first, and Apple records which code was used.

  1. Touch:

    Link tap in TikTok

    /sarah/k7Q2x

  2. Touch:

    Offer code SARAH20 redeemed in the App Store

    VVerifiedWinner
  3. App open:

    App installs; first open links the user

  4. Purchase:

    First paid period, Apple-verified

Being validated · We’re still testing offer-code redemption from TikTok’s browser on real devices.

Landing pageiOS · Instagram in-app browser

Sarah Lee recommends Stretchly

20% off for 3 months

Primary button: Claim 20% off on the App Store

  • “Already have the app? Open it” (universal link, on a real tap)
  • Fallback: “Copy code SARAH20” (on tap), then the creator’s custom product page

Sarah earns a commission.

Method that fires
Apple offer-code redemption link
Best tier
VVerifiedV1 · Apple offer code

Same as TikTok: the landing page never auto-redirects to a universal link, because redirects break them. One button, chosen for this browser.

  1. Touch:

    Link tap in Instagram

    /sarah/k7Q2x

  2. Touch:

    Offer code SARAH20 redeemed in the App Store

    VVerifiedWinner
  3. App open:

    App installs; first open links the user

  4. Purchase:

    First paid period, Apple-verified

Being validated · We’re still testing offer-code redemption from Instagram’s browser on real devices.

Landing pageiOS · link in a YouTube description

Sarah Lee recommends Stretchly

20% off for 3 months

Primary button: Claim 20% off on the App Store

  • Code spoken in the video, typed into your paywall
  • Fallback: “Copy code SARAH20” (on tap)

Sarah earns a commission.

Method that fires
Apple offer-code redemption link
Best tier
VVerifiedV1 · Apple offer code (or U1 if typed)

Description links behave like other in-app browsers. A code said out loud still lands as a typed code (U1), or as V1 when the viewer redeems it in the App Store.

  1. Touch:

    Link tap in YouTube description

    /sarah/k7Q2x

  2. Touch:

    Offer code SARAH20 redeemed in the App Store

    VVerifiedWinner
  3. App open:

    First open links the user

  4. Purchase:

    First paid period, Apple-verified

Being validated · We’re still testing how YouTube opens links, on real devices.

Landing pageiOS · Safari or Chrome

Sarah Lee recommends Stretchly

20% off for 3 months

Primary button: Claim 20% off on the App Store

  • App Clip card or Smart App Banner, if your app has an App Clip
  • Fallback: “Copy code SARAH20” (on tap), then the product page

Sarah earns a commission.

Method that fires
Apple offer-code redemption link
Best tier
VVerifiedV1 · Apple offer code (D4 with an App Clip)

In a real browser the same offer-code path works, and an App Clip can hand the click ID to the full app through shared storage.

  1. Touch:

    Link opened in Safari

    /sarah/k7Q2x

  2. Touch:

    Offer code SARAH20 redeemed

    VVerifiedWinner
  3. App open:

    First open links the user

  4. Purchase:

    Trial converts to paid

Being validated · We’re still testing the App Clip handoff on real devices.

Landing pageAndroid · any browser or in-app browser

Sarah Lee recommends Stretchly

20% off for 3 months

Primary button: Get it on Google Play

  • App Link, if the app is already installed
  • Fallback: Play promo code

Sarah earns a commission.

Method that fires
Play Store with the click ID in the install referrer
Best tier
DDeterministicD2 · Play Install Referrer

The click ID rides through the Play Store install in the referrer, so the match is exact. Its timestamps also catch click injection.

  1. Touch:

    Link tap in Instagram on Android

    /sarah/k7Q2x

  2. Install:

    Play Store install with referrer

  3. App open:

    First open reads proofline_click=k7Q2x

    DDeterministicWinner
  4. Purchase:

    First paid period, Google-verified

Being validated · We’re still testing, on real devices, whether the referrer survives each in-app browser.

Landing pageDesktop browser

Sarah Lee recommends Stretchly

20% off for 3 months

Primary button: Scan to get the app

  • “Text me the link” or “Email me the link”
  • Fallback: App Store and Google Play web pages

Sarah earns a commission.

Method that fires
QR code to the same link
Best tier
VVerifiedSame as phone (plus D5 post-install link)

Nobody installs an app on a laptop. The QR code opens the same creator link on the phone and keeps the click history.

  1. Touch:

    Link opened on a laptop

    /sarah/k7Q2x

  2. Touch:

    QR scanned; same link opens on the phone

  3. Touch:

    Offer code SARAH20 redeemed

    VVerifiedWinner
  4. Purchase:

    First paid period

Landing pageSpoken code (podcast, video, live)

Sarah Lee recommends Stretchly

20% off for 3 months

Primary button: Code field on your paywall

  • “How did you hear about us?” for reporting only

Sarah earns a commission.

Method that fires
In-app code entry
Best tier
UUser-assertedU1 · code typed in the app (V1 if redeemed in the App Store)

There is no link to tap. A typed code shows clear intent and pays by default; a self-reported answer never pays.

  1. Touch:

    Hears “use code SARAH20”

  2. Install:

    Installs from the App Store

  3. Touch:

    Types SARAH20 on the paywall

    UUser-assertedWinner
  4. Purchase:

    First paid period

Engineering rules

Four rules every link follows.

  • The click ID lives in the URL path

    /sarah/k7Q2x, not ?click=… TikTok strips some query parameters, and Safari’s Link Tracking Protection strips known tracking parameters in Private Browsing, Mail and Messages.

  • No JavaScript redirects to universal links

    iOS opens your app from a universal link only on a real tap. Redirects break them, so the page shows one clear button instead.

  • The redirect never waits for logging

    Clicks are written asynchronously. Links keep working even if every backend service is down.

  • Routing, not identification

    The user agent picks the button. It is never stored as an identifier and never used to match a device.

Link Health

A public record of what works where.

Apps change their browsers without notice; Instagram did in 2025. A capability matrix of environment × method, updated by real-device tests and live traffic, will choose the default button per environment and be published as a Link Health page.

Being validatedWe’re testing on real devices now: Instagram, TikTok, Facebook, Snapchat, X, Threads, YouTube, LinkedIn, Pinterest, Reddit, Discord, WhatsApp and Telegram. The public Link Health page follows once the first full run is done.