- An API is a set of rules that lets one piece of software ask another for data or actions.
- REST uses fixed web addresses for each type of data, while GraphQL lets the client ask for exactly the fields it needs.
- REST is simpler to start with, and GraphQL helps when apps need flexible, nested data.
The Short Answer
An API, or application programming interface, is a way for one program to talk to another. When a weather app shows today's forecast, it asks a weather service through an API. Two common styles are REST and GraphQL. REST gives you separate web addresses for each resource, such as users or orders. GraphQL gives you one endpoint where you describe exactly what data you want. Neither is always better, and many teams use both.
An API in Everyday Language
Think of a restaurant. You (the app) tell the waiter (the API) what you want, the waiter goes to the kitchen (the server) and brings back your food (the data). You never enter the kitchen. APIs also power payments, maps and logins. For example, accepting online payments in Nigeria usually relies on a payment provider's API, as covered in our guide to accepting online payments.
REST in Brief
- Each thing has an address, such as
/users/12or/orders. - You use standard actions: GET to read, POST to create, PUT or PATCH to update, DELETE to remove.
- Responses are usually JSON.
- It is simple, widely supported and easy to cache.
GraphQL in Brief
- There is usually one endpoint.
- The client sends a query listing the exact fields it wants.
- You can fetch related data in one request.
- It needs a defined schema and careful server design.
REST vs GraphQL
| Question | REST | GraphQL |
|---|---|---|
| Learning curve | Gentler | Steeper |
| Over-fetching data | Common | Avoided |
| Number of requests | Often several | Often one |
| Caching | Simple | More work |
| Best for | Simple, public or standard services | Complex apps with varied screens |
Using APIs Safely
- Keep API keys secret and never place them in public code.
- Use HTTPS and the minimum permissions.
- Respect rate limits and read the documentation.
- Test with a tool such as Postman or a simple script before building on it.
To connect tools without code, see Zapier vs Make.
Action Checklist
- Read the API documentation first
- Test requests before building
- Store keys securely
- Handle errors and timeouts
- Start with REST unless you need GraphQL
