APIs are a core part of applications. They provide data and functions to other services by exposing part of the code, which is why it’s important to secure them. This guide explains practical API security measures you can apply on your server, from authentication to infrastructure hardening and safe use of mock APIs.
Core Security Must-Haves
Use Token-Based Authentication
To secure an API, you should start with strong authentication. Instead of simple keys, use OAuth tokens or JWT tokens to control access. This approach helps you verify who is calling your API and what they are allowed to do. You can also scope tokens to limit permissions and reduce impact if one is leaked.
Enforce HHTPS for All Requests
Next, you must protect the data in transit. Always expose your API over HTTPS, not plain HTTP. With HTTPS enabled, third parties aren’t able to easily read or modify the traffic between clients and your server.
Validate and Sanitize Inputs
You need to treat all incoming data as untrusted. Validate and sanitize every parameter your API receives, including body content, headers, and query strings. Proper input validation reduces risks such as SQL injection and cross-site scripting before they reach your application logic.
Apply Rate Limiting
You should also control how frequently clients call your endpoints. By adding rate limiting, you prevent single users or scripts from overwhelming your API. This keeps your server responsive and reduces the impact of abuse or simple misconfiguration.
Protect the Infrastructure behind Your API
Use a Reverse Proxy
After you secure the basics, you should look at the infrastructure that sits in front of your API. A common pattern is to use a reverse proxy such as NGINX. The reverse proxy can handle SSL termination, routing, and even basic rate limiting before traffic reaches your backend services.
Add A Web Application Firewall (WAF)
In addition, you can add a Web Application Firewall to filter attacks. Services like Cloudflare or modules like ModSecurity help block known attack patterns and suspicious traffic. They provide another protective layer on top of your own input validation.
Keep the System Updated
You also want to keep your operating system and software stack updated. Regular updates close known security gaps and remove outdated components. Keep in mind to only expose the network ports you really need for your API. A lean, up-to-date system presents a smaller surface for attackers.
Monitor and Maintain Your API
Enable Logging and Monitoring
Good security also depends on visibility. Therefore, you should set up logging and monitoring for your API and infrastructure. Tools such as Prometheus with Grafana help you track metrics, error rates, and traffic patterns over time. With these insights, you can detect unusual behavior and react before it becomes a larger issue.
Version Your API
It is also helpful to version your API. With versioning, you can introduce changes without breaking older applications immediately. This controlled evolution keeps your clients stable while you improve security or add new features.
Secure Use of JSON Server and Mock APIs
Keep JSON Server Private
During development, many teams use tools like JSON Server to mock APIs. JSON Server is very convenient, but it is not designed as a secure public service. This is why you should avoid running it on the open internet. Instead, keep JSON Server local on your machine or place it behind a private network.
Avoid Real Customer Data
Also avoid loading real customer or user data into mock APIs. Development environments are more likely to be misconfigured or exposed by accident. Using only synthetic or test data keeps sensitive information safe, even if the mock API becomes accessible.
Consider More Advanced Mock Tools
If you need more control and stronger features for mock APIs, you can consider tools like Mockoon, Postman mock servers, or WireMock. These tools offer additional flexibility and align better with structured API security best practices, especially in team environments.
API Security Checklist
Use this list as a quick reference when deploying or reviewing an API:
- Authenticate access with OAuth tokens or JWT
- Encrypt all traffic with HTTPS
- Validate and sanitize every input
- Apply rate limiting at API or proxy level
- Use a reverse proxy and, where possible, a web application firewall
- Version your API and manage deprecations
- Keep mock APIs private and free of real user data
These measures work together to improve the security posture of your API and the underlying infrastructure.
Watch Our Video on API Security
If you prefer a visual explanation, you can follow the connected YouTube video.
Conclusion
Securing an API is not a single action but a combination of design decisions and operational practices. With authentication, encryption, input validation, infrastructure protection, monitoring, and careful handling of mock APIs, you significantly reduce common risks.
Applying these helps protect your users, your data, and your services over the long term.