Complete REST API v2 reference for BrandX Booking. Base URL: api.brandxbooking.com/api/v2. Authentication: API key query parameter or OAuth 2.0. Available endpoints: GET/POST/PUT/DELETE /appointments, GET/POST/PUT/DELETE /customers, GET /staff_members, GET /services, GET /appointment_types, GET/POST/DELETE /api_subscriptions (webhooks), POST /authenticate, GET /me. Supports personal access tokens for internal apps and OAuth 2.0 for customer-facing integrations.