Flags

Feature flags support four types — boolean, string, number, and JSON — with per-environment configuration.

Overview

Feature flags are the core primitive in Switchflag. A flag has a key, a type, a default value, and per-environment configuration (enabled state + targeting rules).

Creating a flag

Field	Description	Validation
Name	Display name	1-100 characters
Key	Code identifier	Lowercase, numbers, hyphens. Unique per project.
Type	Value type	`boolean`, `string`, `number`, `json`
Default Value	Fallback value	Must be valid for the type
Description	Optional notes	Up to 500 characters

Flag types

Type	Default Value	SDK Type	Use Case
boolean	`true` or `false`	`getFlag<boolean>`	On/off toggles
string	Any string	`getFlag<string>`	A/B variants, theme names
number	Any number	`getFlag<number>`	Limits, thresholds
json	Valid JSON	`getFlag<{ ... }>`	Complex configs

Flag key

The key is what you use in code:

const result = await client.getFlag<boolean>('new-checkout-flow', ctx)

Keys must be:

Lowercase letters, numbers, and hyphens only (^[a-z0-9-]+$)
Unique within the project
1-100 characters

Default value

The default value is the fallback when:

The flag is enabled but no targeting rules match (non-boolean types)
The flag has no environment configuration

For boolean flags, when the flag is enabled and no rules match, the value is true (not the default value). When disabled, boolean flags return false.

Per-environment state

When a flag is first created, it's disabled in all environments. You control:

Enabled/disabled — toggle independently per environment
Targeting rules — different rules per environment

See Targeting Rules for configuring rules.