Overview The defineFeature() function defines a feature (entitlement) in your billing configuration. It’s an identity function that provides type inference and autocomplete while returning the input as-is.
Features represent capabilities or resources in your product that can be gated based on subscription plans.
Function Signature function defineFeature < T extends FeatureDefInput >( config : T ) : T
Type Parameters T
T extends FeatureDefInput
The feature configuration type. Must extend FeatureDefInput.
Parameters The feature configuration object. Human-readable display name for the feature (e.g., “Team Seats”, “API Calls”).
Optional description for documentation and dashboard display.
type
'boolean' | 'static' | 'metered'
required
The data type of the feature:
boolean: On/Off flag (e.g., SSO Access)static: Fixed numeric limit included in the plan (e.g., 5 Seats)metered: Usage-based, tracked over time (e.g., AI Tokens) unit_type
'count' | 'bytes' | 'seconds' | 'tokens' | 'requests' | 'custom'
required
The unit of measurement for the feature. Used for display, analytics, and billing calculations.
Returns The same configuration object passed in, with full type inference preserved.
Usage Boolean Feature import { defineFeature } from "@revstack/core" ; export const sso = defineFeature ({ name: "Single Sign-On" , description: "SAML/OAuth SSO authentication" , type: "boolean" , unit_type: "count" , });
Static Feature import { defineFeature } from "@revstack/core" ; export const seats = defineFeature ({ name: "Team Seats" , description: "Number of team members who can access the workspace" , type: "static" , unit_type: "count" , });
Metered Feature import { defineFeature } from "@revstack/core" ; export const apiCalls = defineFeature ({ name: "API Calls" , description: "Monthly API request quota" , type: "metered" , unit_type: "requests" , }); export const storage = defineFeature ({ name: "Cloud Storage" , description: "Total storage capacity in bytes" , type: "metered" , unit_type: "bytes" , }); export const aiTokens = defineFeature ({ name: "AI Tokens" , description: "LLM token usage for AI features" , type: "metered" , unit_type: "tokens" , });
Complete Configuration import { defineConfig , defineFeature , definePlan } from "@revstack/core" ; export default defineConfig ({ features: { // Boolean feature sso: defineFeature ({ name: "Single Sign-On" , type: "boolean" , unit_type: "count" , }), // Static feature seats: defineFeature ({ name: "Team Seats" , type: "static" , unit_type: "count" , }), // Metered feature api_calls: defineFeature ({ name: "API Calls" , type: "metered" , unit_type: "requests" , }), } , plans: { starter: definePlan ({ name: "Starter" , is_default: true , is_public: true , type: "free" , features: { sso: { value_bool: false }, seats: { value_limit: 3 }, api_calls: { value_limit: 1000 , reset_period: "monthly" }, }, }), } , }) ;
Feature Types Explained Boolean Features Simple on/off toggles. Use value_bool: true or value_bool: false in plan feature values.
Examples : SSO, Priority Support, Custom BrandingStatic Features Fixed limits that don’t reset. Use value_limit in plan feature values.
Examples : Team Seats, Projects, WorkspacesMetered Features Usage-based limits that can reset periodically. Use value_limit and reset_period in plan feature values.
Examples : API Calls, Storage, AI Tokens, Email SendsSource Location : packages/core/src/define.ts:18-20