API vs SDK - What's Actually Different?
APIs expose data and actions over the wire. SDKs ship libraries and tools for one platform. When to pick which, with plain examples.
People swap "API" and "SDK" in meetings constantly. They're related, not interchangeable.
API
An API is a contract: endpoints, auth, request shapes, response shapes. Your app calls it over HTTP (usually) and gets data or triggers actions. Google Maps embed, Stripe charges, your own REST backend.
APIs are often platform-agnostic. Same HTTP call from Node, Python, mobile.
SDK
An SDK is a toolbox for building on a specific platform. Libraries, docs, sample code, sometimes CLI tools. iOS SDK, Android SDK, vendor JS package with helpers around their API.
SDKs tend to be platform-bound. They wrap complexity so you don't hand-roll every HTTP call.
Practical differences
APIs give you access to remote capability. SDKs give you local building blocks (which may call APIs under the hood).
APIs are harder to customize; you consume what the vendor exposes. SDKs let you compose app code around typed helpers, though you're still boxed in by the SDK's design.
Why pick an API
Faster integration when you only need a few endpoints. Works across stacks. Good when your team already has HTTP patterns they trust.
Downside: you own retries, auth refresh, error mapping, and versioning surprises.
Why pick an SDK
Official clients handle auth headers, pagination quirks, and model types. Great for mobile or when the vendor maintains first-party packages.
Downside: another dependency, release cadence tied to the vendor, sometimes bloated for a single endpoint.
Decision shortcut
Need one endpoint from a service? HTTP + API docs is fine.
Building a native mobile app against a big product surface? SDK probably saves time.
Mixing both is normal: SDK in the app, API for your backend sync job.
Integration reality
Read the docs before coding. Map which fields you need. Plan error paths. Test with sandbox keys.
Popular pairs people mention: Google Maps API, Facebook/Meta SDKs for social login flows.
Wrap-up
Neither is "better." APIs are the remote door. SDKs are the local power drill. Match the tool to who maintains the integration and how often the vendor changes shapes.
If you're designing a platform, expose a clear API first. SDKs are optional sugar on top.