Flags

Boolean Flag

The simplest flag: on or off. When active, flag.enabled is true for all users in the environment.


const flag = canary.getFlag('maintenance-mode')
// flag.type === 'boolean'
// flag.enabled === true | false

When to use:

Kill switches / maintenance
Complete features you want to release to everyone at once
Integrations or modules that require manual activation

Rollout Flag

Exposes the feature to a percentage of users in a sticky (deterministic) way. A user with the same userId will always receive the same result for a given percentage configuration.


const flag = canary.getFlag('new-dashboard')
// flag.type === 'rollout'
// flag.enabled === true | false (based on userId and percentage)
// flag.percentage === 25 (the currently configured percentage)

The SDK determines whether the user is included via a hash of userId combined with the flag name — with no server-side state per user.

When to use:

Canary deploys (expose to 5% → 25% → 100%)
Simple A/B tests
Beta features for early adopter users

Common fields

Field	Type	Description
`key`	`string`	Unique flag identifier in the environment
`type`	`'boolean' \| 'rollout'`	Flag type
`enabled`	`boolean`	Whether the flag is active for the current user
`description`	`string \| null`	Optional description

SDK access


// Specific flag
const flag = canary.getFlag('feature-key')
 
// All flags
const flags = canary.getFlags()
 
// Safe check (returns false if the flag does not exist)
const isEnabled = canary.getFlag('feature-key')?.enabled ?? false

The SDK does not expose an isEnabled() method — always use getFlag(key)?.enabled ?? false for simple checks.