A public API is an application programming interface that lets external developers access a software service or data through documented rules. It enables one application to request information or actions from another over the internet. Public means available beyond a company’s internal systems, not necessarily free or unrestricted.
Public API
A public API is an application programming interface that lets external developers access a software service or data through documented rules. Public means available outside a company, not necessarily free, anonymous, or unlimited.
What Is a Public API?
It lets one application request data or trigger an action in another application over the internet.
How a Public API Works
Apps follow the provider's published contract.
- Read the API documentation.
- Create an account or obtain a key.
- Send an API request to an endpoint, such as a weather forecast URL.
- Read the structured JSON response.
- Handle errors and rate limits.
Public API vs Private API
Partner APIs sit between these models.
| Public | Private |
|---|---|
| External developers | Internal teams |
| Published documentation | Restricted documentation |
| Keys, quotas, support terms | Company-controlled access |
Benefits of Public APIs
They avoid rebuilding common capabilities.
- Add maps, payments, data, or messaging faster.
- Use specialist services while reducing maintenance.
Practical Limits and Security Risks
Access always has conditions.
- Free plans may impose quotas, pricing tiers, or commercial restrictions.
- Protect keys, request only needed permissions, and plan for outages or version changes.
How to Choose a Public API
Evaluate more than its feature list.
- Check documentation, authentication, versioning, limits, pricing, data rights, reliability, support, and a sandbox.
Building With Public APIs in Emergent
Emergent can turn a description into an API-powered app, connect approved services, test requests, and ship it. Learn about API integration, secure an API key, or build a Spotify API app.
Frequently Asked Questions
Your Questions, Answered
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What is a public API?
A public API is a documented interface that allows outside developers to access a software service or dataset programmatically.
Is a public API free?
Not always. A public API may be free, have a limited free tier, or charge by usage.
Can you give me some examples of public APIs?
Examples include weather, mapping, payment, government-data, and social-media APIs.
Is Google Maps a public API?
Google Maps Platform provides public APIs for developers, but usage requires a project, billing setup, and adherence to its terms.
Which Google API is free?
Some Google APIs offer free quotas or no-charge access, but availability and limits vary by product. Check the current documentation and pricing page.
Does GitHub have an API?
Yes. GitHub provides REST and GraphQL APIs for repositories, issues, pull requests, and other GitHub resources.
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