API Glossary
Essential API terminology every developer should know
API (Application Programming Interface)
A set of definitions and protocols that allows different software applications to communicate with each other. APIs define the methods and data formats that applications can use to request and exchange information.
Example: Requiems API provides a REST API for validating email addresses programmatically.
Endpoint
A specific URL where an API can access the resources it needs. Each endpoint corresponds to a specific function or resource in the API.
Example: POST /v1/email/disposable/check
Authentication
The process of verifying the identity of a user or application. APIs typically require authentication to ensure only authorized users can access the service.
Example: Including your API key in the Authorization header: Authorization: Bearer YOUR_API_KEY
API Key
A unique identifier used to authenticate requests to an API. API keys act as both an identifier and a secret token for authentication.
Example: req_live_1234567890abcdef
Rate Limiting
A technique used to control the number of requests a user can make to an API within a given time period. This helps prevent abuse and ensures fair usage.
Example: Free plan allows 100 requests per minute
Requests
The unit of API usage. Each API call counts as 1 request against your monthly plan allowance. Some endpoints may count as more than 1 request β this is always stated explicitly in that endpoint's documentation.
Example: Calling the email validation endpoint once uses 1 request from your monthly allowance.
REST (Representational State Transfer)
An architectural style for designing networked applications. REST APIs use HTTP requests to perform CRUD (Create, Read, Update, Delete) operations on resources.
Example: Using GET to retrieve data, POST to create, PUT to update, DELETE to remove
JSON (JavaScript Object Notation)
A lightweight data interchange format that's easy for humans to read and write, and easy for machines to parse and generate. Most modern APIs use JSON for request and response bodies.
Example: {"email": "[email protected]", "is_disposable": false}
HTTP Status Codes
Three-digit codes returned by web servers to indicate the result of an HTTP request. Common codes include 200 (success), 404 (not found), and 500 (server error).
Learn more: Error Codes Reference
Webhook
A method for an application to provide real-time information to other applications. Instead of you making repeated API requests, the server sends data to your specified URL when an event occurs.
Example: Receive a notification when your request balance drops below a threshold
Query Parameters
Key-value pairs appended to a URL to filter, sort, or modify the API response. They appear after a question mark (?) in the URL.
Example: /v1/words?limit=10&min_length=5
Headers
Additional information sent with HTTP requests and responses. Headers can contain authentication tokens, content types, custom metadata, and more.
Example: Content-Type: application/json
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