Build, test, deploy, install, and certify production-ready commercetools Connect applications — service/API-extension, event/subscription, job, and merchant-center custom apps — in TypeScript, JavaScript, or Java, and integrate a deployed connector into a custom storefront. Covers the connect.yaml contract, least-privilege scopes, lifecycle scripts, sync-vs-async idempotency/ack, testing, and deployment. Includes connector sub-areas for payment (Stripe, Adyen, PayPal), tax (Avalara, Vertex, TaxJar), PIM (Akeneo), CRM (Salesforce, HubSpot), order-management/OMS, gift cards, transactional email (SendGrid, Mailgun), marketplace (Mirakl), promotion and loyalty (Talon.One, Voucherify), analytics export to a warehouse/CDP (BigQuery, Snowflake, Segment), and search/product discovery (Algolia). Use when building, configuring, forking, or debugging a commercetools Connect connector, or syncing commercetools data to or from an external system. Not for the hosted Checkout widget (see commercetools-checkout).