How can you make a secure web API that communicates with other web services?

2 Implement authentication and authorization

The next step to make a secure web API is to implement authentication and authorization mechanisms that verify the identity and permissions of the web services that access your web API. Authentication is the process of verifying who the web service is, while authorization is the process of verifying what the web service can do. There are different methods and standards for authentication and authorization, such as API keys, OAuth, JWT (JSON Web Tokens), or OpenID Connect. You should choose the method that suits your web API's needs and requirements, and implement it using a reliable library or framework.

3 Validate and sanitize inputs and outputs

The third step to make a secure web API is to validate and sanitize the inputs and outputs that your web API receives and sends to other web services. Validation is the process of checking if the inputs and outputs conform to the expected format, type, length, or range. Sanitization is the process of removing or escaping any harmful or malicious characters or code from the inputs and outputs. These steps can help you prevent common web API vulnerabilities, such as injection attacks, cross-site scripting (XSS), or buffer overflow. You can use built-in or third-party validators and sanitizers for your web API's language or framework.

4 Handle errors and exceptions

The fourth step to make a secure web API is to handle errors and exceptions that may occur during the communication with other web services. Errors and exceptions are unexpected or undesirable situations that interrupt the normal flow of your web API. They can be caused by various factors, such as network failures, invalid requests, or internal bugs. You should handle errors and exceptions gracefully, by returning appropriate status codes, messages, and logs. You should also avoid exposing sensitive or detailed information about your web API's errors and exceptions, as they can be exploited by attackers.

5 Monitor and test your web API

The fifth step to make a secure web API is to monitor and test your web API regularly and continuously. Monitoring is the process of collecting and analyzing data about your web API's performance, availability, and usage. Testing is the process of checking and verifying your web API's functionality, reliability, and security. These steps can help you identify and fix any issues or vulnerabilities that may affect your web API's security and quality. You can use various tools and services for monitoring and testing your web API, such as Postman, Insomnia, New Relic, or Zapier.