@automattic/calypso-products/src/is-free-plan.ts

This module contains information about the various products sold within calypso, such as product slugs, plan intervals, etc.

import { camelOrSnakeSlug } from './camel-or-snake-slug';
import { PLAN_FREE } from './constants';
import type { WithSnakeCaseSlug, WithCamelCaseSlug } from './types';

export function isFreePlanProduct( product: WithSnakeCaseSlug | WithCamelCaseSlug ): boolean {
	return product && camelOrSnakeSlug( product ) === PLAN_FREE;
}