Flag Types

Flagpool supports four flag types. Each type determines what kind of values the flag can return.

Boolean

The most common flag type. Returns true or false.

Use cases: feature toggles, kill switches, permission gates.

if (client.isEnabled('new-checkout')) {
  showNewCheckout()
}

Default variations:

Index	Name	Value
0	On	true
1	Off	false

String

Returns a string value. You can define multiple string variations.

Use cases: A/B tests, theme selection, copy experiments, variant routing.

const color = client.getValue('cta-button-color')
// 'blue' | 'green' | 'orange'

Example variations:

Index	Name	Value
0	Blue	"blue"
1	Green	"green"
2	Orange	"orange"

Use targeting rules or rollout percentages to control which users get which variation.

Number

Returns a numeric value.

Use cases: rate limits, thresholds, batch sizes, configuration values.

const limit = client.getValue('max-upload-size-mb')
// 10 | 100 | 500 | 1000

Example variations:

Index	Name	Value
0	Free	10
1	Pro	100
2	Enterprise	1000

Combined with targeting rules (e.g., plan eq "enterprise" → variation 2), this lets you gate numeric limits by subscription tier.

JSON

Returns a structured JSON object. Useful when you need to configure multiple settings with a single flag.

Use cases: complex feature configurations, multi-value experiments, layout configurations.

const config = client.getValue('checkout-config')
// { showCoupons: true, maxItems: 50, paymentMethods: ['card', 'paypal'] }

Example variations:

Index	Name	Value
0	Default	{ "showCoupons": false, "maxItems": 10 }
1	Enhanced	{ "showCoupons": true, "maxItems": 50 }

JSON flags are powerful but harder to manage. Prefer simpler types when possible and reserve JSON for cases where multiple values must change together.

Choosing the right type

Scenario	Recommended type
Feature on/off	Boolean
Kill switch	Boolean
A/B test between two designs	String
Rate limit per plan	Number
Complex feature config	JSON
Theme/color selection	String
Batch size tuning	Number

Variations

Every flag has an array of variations — the possible values it can return. The number of variations depends on the flag type:

• Boolean flags always have exactly 2 variations (true/false)
• String, Number, and JSON flags can have 2 or more variations

Targeting rules and rollout logic select which variation to return by referencing the variation index (0, 1, 2, ...).

Reading flag values in code

Method	Best for	Returns
isEnabled(key)	Boolean flags	boolean
getValue(key)	Any flag type	The raw variation value
getVariation(key)	Alias for getValue	The raw variation value

In React:

Hook	Best for	Returns
useFlag(key)	Boolean flags	boolean
useFlagValue(key, default)	Any flag type	The variation value (typed)
useFlagDetails(key, default)	Any type + loading states	{ value, isLoading, error }

Next steps

• Feature Flags — how evaluation works end to end
• Targeting — route users to specific variations
• A/B Testing Guide — string flags in practice