---
title: "What is API? | Chargezen"
description: "A defined way for one piece of software to ask another for data or to take an action, without a person clicking through screens."
url: "https://chargezen.com/glossary/api"
lang: "en"
---

Canonical URL: https://chargezen.com/glossary/api

# API

Application programming interface (API)

E-commerce

A defined way for one piece of software to ask another for data or to take an action, without a person clicking through screens.

## What is API?

An API is a set of requests a system agrees to answer. Your store app can ask a shipping service for rates, a payment service to charge a card, or a subscription app to skip a customer's next order, all through APIs. **How it works, in plain terms:** - A **request** goes to an address (an endpoint), with a key that proves who is asking. - The system checks what that key is allowed to do. - It sends back a **response**: the data, a confirmation, or an error that explains what went wrong. **Common types you will hear about:** - **REST APIs,** where each kind of thing (orders, customers) has its own address. - **GraphQL APIs,** where you ask for exactly the fields you need in one request. Shopify's Admin API works this way. - **Webhooks,** the reverse direction: the system tells you when something happens, such as a new order. **Why stores care:** - Apps can share data without exports and spreadsheets. - Headless storefronts and mobile apps are built on APIs. - AI assistants use APIs, often through the Model Context Protocol, to look things up and act for you. **Good APIs are scoped and logged.** Give each key only the access it needs, and keep a record of what it did. **How Chargezen handles it:** Chargezen offers developer tools, including a Subscriptions API, and an MCP server so AI apps like ChatGPT and Claude can work with your Chargezen data within the permissions you grant.

## Example

A brand's mobile app shows each subscriber's next delivery. When a subscriber taps Skip, the app sends a request to the subscription API, which skips the order and replies with the new delivery date.

## Why API Matters

APIs let your tools work together and let you build custom experiences without waiting for an app to add a feature.

## Explore More Terms

Browse our complete glossary of e-commerce and subscription terms.

[View Full Glossary](https://chargezen.com/glossary)