Matching

Attribution answers one question: does this first app open belong to a click Detour recorded a few minutes ago? The answer is either an exact match or a score. This page describes how the server decides and which settings you can change.

How matching starts

On first app open the SDK calls the Detour match API. The server picks one of two matching modes based on what the payload contains.

flowchart TD
    A[First app open] --> B{clickId present?}
    B -->|Yes| C[Deterministic lookup]
    B -->|No| E[Probabilistic scoring]
    C --> D{Click exists<br/>and unmatched?}
    E --> F[Load unmatched clicks<br/>in the time window]
    F --> G[Score candidates,<br/>keep the highest]
    G --> H{Score above<br/>the threshold?}
    D -->|Yes| M1[Return link URL]
    D -->|No| N1[Return 404]
    H -->|Yes| M2[Return link URL]
    H -->|No| N2[Return 404]

A returned link URL marks the install as non-organic. A 404 stores it as organic. The default score threshold is 850.

Matching modes

• Deterministic (preferred) — an exact clickId is present, from the Android install referrer. The server looks it up and returns the link if that click exists and is still unmatched. The lookup is exact.
• Probabilistic (fallback) — no clickId, which is the norm on iOS. Detour scores the device fingerprint sent by the SDK against recent unmatched click beacons.

Probabilistic payload

The SDK sends these fields when there is no clickId:

Field	Type	Meaning
platform, model, manufacturer, systemVersion	string	Device signature
screenWidth, screenHeight, scale	number	Screen size and pixel ratio
locale	{ languageTag: string }[]	Device languages. languageTag is scored.
timezone	string | null	Device timezone
userAgent	string	Raw user agent
timestamp	number	Capture time in Unix milliseconds, checked against the match window
pastedLink	string, optional	iOS only. Clipboard content, compared with the click URL and its token

Clipboard is an iOS-only signal

Every SDK sends pastedLink as null on Android. Reading the clipboard there raises a system toast and is restricted to foreground apps, so the Android and Flutter SDKs never attempt it and the React Native SDK gates the read on Platform.OS === "ios". An Android probabilistic match is therefore scored without the 350-point pasteboard signal, so the Play Install Referrer is the main deterministic signal on Android.

Scoring weights

The server scores each candidate click using separate scoring functions. The weights used by Detour today:

Signal	Weight	Scored on
IP exact	500	iOS + Android
Model + system version exact	450	Android *
iOS system version match	350	iOS
User-agent device signature match	350	Android
Pasteboard URL/token match	350	iOS
Timezone	200	iOS + Android
Screen match	200	iOS + Android
Language match	100	iOS + Android

^*The model and system version come from high-entropy client hints. The check itself is platform-agnostic, but WebKit does not implement those hints, so only Android browsers supply the values.

The highest weights go to the signals that are hardest to spoof or to match by coincidence: IP, device signature, and clipboard. Weaker signals such as language add only a small score.

Rules that change the totals at runtime:

• Only one device signal is scored per candidate.

  Model + system version is used when the browser supplies both. On iOS it never does, so the system version parsed from the click’s user agent is scored instead. The user-agent device signature is the fallback everywhere else. The highest reachable total is therefore 1700 on iOS and 1450 on Android.

• Screen comparison allows a tolerance of ±1 on width and height, ±0.01 on scale.

• The iOS pasteboard score has two tiers:

  • 350 when the token matches and the pasted URL starts with the click URL.
  • 175 when only the URL prefix matches.

Threshold and time window

Both values are app-level settings from Link settings → Matching configuration:

• Matching threshold — default 850, allowed range 700..1200
• Matching time window — default 15 minutes, allowed range 5..180 minutes

Customizing the threshold

The default of 850 balances accuracy and recall. Change it when you need a different trade-off:

• Lower (for example 700) finds more matches but attributes more installs to the wrong link. Usually acceptable for general marketing links.
• Higher (for example 1000) is stricter and misses some legitimate matches. Prefer it when links point at sensitive content.

Clicks outside the window are ignored. The window is measured between the click timestamp and the fingerprint timestamp. The default of 15 minutes covers a normal install and limits the number of false positives.

Customizing the time window

The default of 15 minutes is configurable.

• Shorter (5–10 minutes) raises confidence, because the click and the first open are close in time. Slow downloads then fall outside the window and are not matched.
• Longer (30–60 minutes) matches users who were interrupted during the install, but it enlarges the candidate pool and raises the false-positive rate.

Candidate selection

In probabilistic mode the server:

1. Loads the app’s unmatched clicks inside the configured time window.
2. Scores every candidate.
3. Keeps the highest score.
4. Breaks ties in favor of the newer click.
5. Accepts the highest-scoring candidate only if its score is >= threshold.

After a match

A successful match does three things:

• marks the click as matched,
• stores the install as non-organic in the analytics install stream,
• returns the resolved link URL.

With no match, the install is recorded as organic and the API returns 404.

Example scores

• iOS — IP + exact pasteboard token and URL — 500 + 350 = 850. Accepted at the default threshold.
• Android — IP + user-agent device signature — 500 + 350 = 850. Accepted at the default threshold.
• Timezone + language + screen — 200 + 100 + 200 = 500. Rejected.

Tuning

Start with the defaults and change them only after you have seen real traffic in analytics. If too many matches are missed, lower the threshold or extend the time window. If you see cross-attribution in dense traffic, raise the threshold or shorten the window.

For practical edge cases that affect tuning decisions, see Limitations & Known Issues.

Related pages

Click Handling & Redirect Flow What happens when a user clicks a link.

Limitations & Known Issues Platform constraints and known issues.

Analytics Privacy-aware link and event analytics.

Getting Started with Detour Set up your first app from account to first link.