Web Dev Concept

API

A defined contract that lets two software systems talk to each other in a predictable way.

Overview

An API, or application programming interface, is a defined set of rules that lets one piece of software request services or data from another. It is a contract: the provider says what requests it accepts and what responses it returns, and any client that follows that contract can integrate without knowing how the other system works internally.

APIs are how modern software connects. When your app shows a map, processes a payment, or pulls data from another service, it is almost always calling an API. Most web APIs today exchange structured data such as JSON over standard web protocols.

How it works

A client sends a request to a defined endpoint, often over HTTP, describing what it wants. The server validates the request, does the work, and returns a structured response, typically JSON, along with a status. Authentication controls who may call it, and the contract keeps both sides in sync.

  • Endpoints define the available operations and data
  • Requests and responses follow an agreed structure, commonly JSON
  • Authentication and rate limits govern who calls it and how often

Why it matters

APIs let you reuse capabilities instead of rebuilding them, integrate best-in-class services, and decouple systems so parts can evolve independently. They are the foundation of headless architectures, integrations, and any product that talks to another product.

How REO Rank applies it

We design and build APIs and integrations that connect a client's systems cleanly, with clear contracts, authentication, and versioning, so their software, and third-party tools, can exchange data reliably without brittle glue code.

Common questions

API — questions

Straight answers on how this fits your marketing and build.

A website returns pages for humans to read; an API returns structured data for other software to use. The same backend often powers both, serving pages to browsers and data to APIs.

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