Architecture
An SDK is a packaged set of tools, libraries, code samples, documentation, and APIs provided by a platform or service vendor that enables developers to build applications that integrate with or extend that platform.
SDKs dramatically reduce integration effort by providing pre-written code that handles authentication, request formatting, error handling, and data serialisation for a specific platform — rather than requiring every developer to write this boilerplate from scratch. A payment SDK like Stripe's wraps the raw HTTP API with idiomatic library methods (stripe.paymentIntents.create()), handles webhook signature verification, and includes typed response objects for safer error handling. Mobile SDKs (e.g., Firebase SDK for Android or iOS) provide platform-native implementations that handle deep integration with device capabilities like push notifications, local storage, and analytics event tracking. The distinction between an SDK and an API is that an API is the interface specification (the contract), while the SDK is a concrete implementation that makes using that API easier in a specific language or environment.
Example
A retail mobile app integrates the Razorpay Android SDK, enabling the engineering team to add a full payment checkout flow in two days instead of two weeks by using pre-built UI components and API wrappers.
Related terms
API (Application Programming Interface)
An API is a defined set of rules and protocols that allows one software application to request and exchange data or functionality with another, acting as a structured contract between systems.
REST API (Representational State Transfer API)
A REST API is a web API that follows the REST architectural style, using standard HTTP methods (GET, POST, PUT, DELETE) and stateless communication to expose resources identified by URLs.
Webhook
A webhook is an HTTP callback mechanism in which one application automatically sends a real-time data payload to a designated URL in another application whenever a specific event occurs, enabling event-driven integrations without polling.
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