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A segment in Fleack is an eligibility filter that determines which users qualify to participate in a test. When a user makes a request that would otherwise be rewritten by a running test, Fleack checks whether that user matches the test’s segment. If they do, they get assigned to a variant. If they don’t, the response passes through unchanged. Segments let you run targeted experiments — rolling out a price change to high-LTV users only, or testing a feature exclusively on iOS — without writing any custom logic.

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Attribute sources

Segments are built from two categories of attributes: Built-in attributes are extracted automatically from every request Fleack proxies:
  • platform — one of ios, android, unity, or web, derived from the User-Agent header
  • language — the app’s locale, from the Accept-Language header
  • country — derived from the request’s IP address
Profile attributes are extracted over time from your user-data endpoints — the ones Fleack classifies as returning per-user responses. As Fleack observes these responses, it builds up a profile for each user. Common profile attributes include:
  • arpu — average revenue per user
  • level — the user’s current progression level
  • days_since_install — days elapsed since first seen
  • ltv_tier — a lifetime value tier (e.g. whale, mid, low)
Profile attributes are auto-discovered: any scalar field that appears consistently in your user-data responses becomes available as a segment attribute automatically. You don’t need to configure a schema.

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Operators

Segment rules support the following comparison operators:
OperatorMeaning
eqEquals
neqNot equals
inValue is in a list
ninValue is not in a list
gtGreater than
gteGreater than or equal to
ltLess than
lteLess than or equal to
betweenValue is within a range (inclusive)
A user matches a segment only if every rule in that segment evaluates to true. Rules are combined with AND logic.

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Example

To target experienced iOS users who have been using the app for at least a week: 
platform eq ios
AND days_since_install gte 7
Only users whose platform is ios AND whose days_since_install is 7 or more will be assigned to a variant. All other users see the unmodified backend response.

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The “All users” default

When you create a test without selecting a segment, it defaults to All users — no filter is applied and every exposure counts, regardless of platform, language, or profile. This is the right starting point for most first tests.
Start broad with “All users” to gather data quickly, then use segments on follow-up tests to verify whether the effect holds for specific sub-populations, or to roll out a winner to a cautious group first.
Profile attributes become available in the segment builder only after Fleack has observed the relevant user-data endpoint enough times to establish them. If an attribute you expect isn’t showing up, send more traffic through the proxy from users who have that field in their responses.