Feature Flags

Feature flag evaluation requires a server-side SDK. The evaluation API uses management credentials that must not be exposed in browsers or mobile apps. To use flags client-side, call your own backend endpoint which evaluates flags securely on the server and returns the results.

Feature flags let you control feature rollouts, A/B tests, and kill switches remotely without deploying code. The SDK evaluates flags against the SeeStack backend and caches results locally for performance.

Evaluate a Single Flag

const flag = await SeeStack.getFlag('new-checkout-flow', 'usr_1234', {
  plan: 'pro',
  country: 'SA',
});

if (flag.enabled) {
  renderNewCheckout(flag.value); // e.g. "variant-b"
} else {
  renderLegacyCheckout();
}

flag = seestack.get_flag("new-checkout-flow", user_id="usr_1234", attributes={
    "plan": "pro",
    "country": "SA",
})

if flag.enabled:
    render_new_checkout(flag.value)  # e.g. "variant-b"
else:
    render_legacy_checkout()

flag, err := seestack.GetFlag("new-checkout-flow", "usr_1234", map[string]any{
    "plan":    "pro",
    "country": "SA",
})

if flag.Enabled {
    renderNewCheckout(flag.Value) // e.g. "variant-b"
} else {
    renderLegacyCheckout()
}

Evaluate All Flags

Fetch all flag values for a project in a single call:

const flags = await SeeStack.getAllFlags('usr_1234', { plan: 'pro' });

if (flags['dark-mode']?.enabled) {
  enableDarkMode();
}

flags = seestack.get_all_flags(user_id="usr_1234", attributes={"plan": "pro"})

if flags.get("dark-mode", {}).get("enabled"):
    enable_dark_mode()

flags, err := seestack.GetAllFlags("usr_1234", map[string]any{"plan": "pro"})

if flag, ok := flags["dark-mode"]; ok && flag.Enabled {
    enableDarkMode()
}

Flag Result

Prop

Type

Flag Types

All flag values are returned as strings. Cast them to the appropriate type in your code:

Type	Example `value`	How to Use
`boolean`	`"true"` or `"false"`	Parse as boolean
`string`	`"variant-b"`	Use directly
`number`	`"42"`	Parse as number

Parameters

getFlag

Prop

Type

getAllFlags

Prop

Type

Returns a Record<string, FlagResult> mapping flag keys to their evaluation results.

Next Steps

Configuration

SDK API Reference

Data Models

Returns a Record<string, FlagResult> mapping flag keys to their evaluation results.

Caching

The SDK caches flag evaluation results to minimize network calls:

Scenario	Behavior
Cache hit (within 60s)	Returns cached value immediately
Cache miss	Fetches from backend, caches result
Network failure	Returns last cached value (stale-on-error)
First call, no cache	Returns the default value from flag configuration

The cache TTL is 60 seconds by default. After expiry, the next evaluation triggers a fresh fetch from the backend.

Rollout percentages are computed server-side based on userId. You do not need to implement any rollout logic in your code.

Feature Flags

Configuration

SDK API Reference

Data Models

On this page