Definition: What Is API Response Time?

API response time is the total amount of time it takes for an API to receive a request, process it and send a response back to the client. The measurement of the response time starts as soon as the client initiates a request and ends when the client receives the response from the server.

Why Is API Response Time Important?

API response time plays a critical role in the functionality of an application as it directly affects the user experience (UX). If it takes too long to respond to an API request, it can result in a frustrating experience for the user, leading them to abandon the application altogether.

API response time is also related to the efficiency and scalability of an application. If the API takes too long to respond, it won’t be able to serve multiple requests in a short amount of time. This can directly affect the efficiency and scalability of the client application. The impact is even greater in the case of real-time applications like online gaming, stock trading, or chat.

Another reason where API response time plays a critical part is search engine optimization (SEO). Page load time is one of the key factors search engines like Google consider when ranking a website. Therefore, a slower API response time could negatively affect the search engine ranking of a website using the API.

API Latency vs. Response Time

Response time and latency are two popular terms when talking about APIs. You may have seen them used interchangeably. However, they are two different things.

API latency is the time delay between sending the last byte of a request to an API server and receiving the first byte of the response from the server. In other words, it is the total time a request takes to travel between the server and client computers. Latency is directly affected by the number of proxy servers and the physical distance between two computers. For example, the API latency is significantly higher for a client in the US and a server in Australia compared to a client in the US and a server in the UK.

On the other hand, the API response time period starts after the last byte of a request is sent by a client and ends when the client receives the last byte of the processed response. It’s approximately the sum of API latency and the time the server takes to process the request. API latency is directly affected by the server’s processing power and response size. For example, API response time is significantly higher when processing a 20 MB file than when processing a 20-byte file.

To understand the difference between API response time and API latency, we can also take an example of a food order in a restaurant. API response time is the time it takes for the prepared food to reach your table after the waiter has taken your order. API latency is the sum of the time it takes for the waiter to reach the kitchen door from your table and the time it takes for the waiter to return from the kitchen door to your table. It doesn’t include the time the chef takes to prepare your food.

What Is the Acceptable API Response Time?

The acceptable API response time is the maximum response time that can be allowed to maintain a smooth and uninterrupted user experience. This time may vary depending on the type of application that utilizes the API. For example, applications that don’t require immediate response can work with an API with a higher response time but applications that require immediate response demand a lower API response time. It’s essential to set an acceptable API response time that aligns with the application’s needs to avoid any negative impact on the user experience.

• Low API response times are essential for real-time applications like online gaming and trading apps. The most preferred API response time for such applications is 0.1 seconds, which can be counted as an immediate response where users won’t feel any interruption.
• Moderate API response times are acceptable for interactive applications like e-commerce websites and social media platforms. The maximum acceptable API response time for such applications is 1.0 seconds. This is when users start experiencing some delay, but not enough to abandon the website or application altogether.
• Higher API response times are acceptable for non-interactive applications like reporting and data processing. While the maximum tolerable response time for such applications is 10.0 seconds, a user usually abandons the application or website after 6.0 seconds.

So, it is important to monitor the API response time and adjust it according to the needs of the application.

Types of API Response Metrics

You can use three types of metrics to monitor the API response time:

• Average response time – It’s the average time an API takes to respond to requests. This value is calculated using a sample of requests. It is an excellent indicator of the overall performance of an API.
• Peak response time – This is the maximum response time taken for a request out of a sample of processed API requests. This metric could help to detect the components, such as database, web server, or network, that could affect the API response time. For example, during normal load conditions, the average response time of an API could be relatively low. However, with a sudden increase in the number of orders, the database could experience a performance issue, which can increase the API’s peak response time.
• Error rate – It is the percentage of error responses and timed-out responses against all the requests in a sample. This metric is generally calculated by measuring the HTTP error codes.

What Causes Poor API Response Times?

To resolve any issues resulting from a poor API response time, you must understand the reasons for poor API response times. Here are several of them:

• Low API server performance – The capacity and performance of the server that hosts the API undoubtedly affect the response time. It might take longer to process requests if the server is overloaded or underpowered, leading to poor response times.
• Greater physical distance between the client and the server – There will be higher latency if the distance between the API server and the client is long.
• A high number of proxy servers involved – The response time increases if the number of proxy servers between the client and the server increases.
• Poor coding on the server – Sometimes, the application code can be unoptimized with inefficient algorithms, or there can be poor database schema designs and large volumes of data to process. All these things can result in poor API response times.
• Security measures – Heavy encryption and authentication mechanisms implemented for security purposes can also slow down the response time.
• Third-party dependencies – Third-party dependencies for the API might also lead to poor API response time.

How to Check API Response Time?

You can measure API response time in many ways. While a simple ping test is the most basic measurement, it won’t always provide accurate results. Additionally, there are many tools out there to aid you in measuring the response time. For example, you can use:

• API stress testing tools such as Apache JMeter and LoadRunner. You can use these tools to monitor the response time and receive alerts when it exceeds the limit.
• API monitoring solutions like Sematext Synthetics to measure API response time. They allow you to track and alert on key API metrics and receive notifications to help improve the performance, functionality, and availability of your APIs.

To check the API response time, simulate the load and capture the speed using your preferred tool. It is always a good idea to gather the API response time measurement from different tools because the architecture of the two tools can be different, resulting in different API response times.

How to Optimize API Response Time?

Optimizing the API response time is essential if you encounter any poor API response times. Here are some of the widely used methods for optimizing API response time.

• Caching – This is one of the best ways to improve response time. It can be achieved by caching the common API responses for end users. These cached responses will eliminate the need to query the database repeatedly for each request, enhancing API performance.
• Route optimization – You should identify the fastest route to the origin for each API request. It’s better to route all requests to the nearest available server to minimize their travel distance. Routing the request to the nearest server significantly reduces the response time.
• Limiting the payloads – Reducing the amount of data that needs to be transferred per response also reduces the response time. It can be done by optimizing the response format to use binary or compressed data.
• Optimizing the code – You can also reduce the API response time by improving the efficiency of the algorithms and data structures used in your code and reducing the number of database queries.
• Load balancing – You can use load-balancing techniques to distribute the server workload. It will reduce the response time by decreasing the workload of each server.
• Investing in good infrastructure – No matter how efficiently the API is designed to work, there should be good infrastructure to ensure the performance of the API. Therefore, it is important to have proper infrastructure, such as reputable hosts and sufficient cloud infrastructure. Implementing server mirrors or CDNs also reduces the API response time.
• Asynchronous processing – The response time will increase if a request has to wait before being processed until a resource is available or another time-consuming task is completed. This issue can be prevented using asynchronous processing techniques such as message queues and event-driven architectures.

API Response Time Monitoring with Sematext

Sematext Synthetics features API monitoring capabilities designed to ensure optimal performance and seamless user experience.

Sematext provides detailed breakdowns of each API metric, including API response times, allowing you to dive deep into the performance characteristics of your APIs and identify any bottlenecks or areas for improvement. You can track API response times on a global scale to help you deliver great user experience regardless of their location. This allows you to gain insights into the performance of your APIs and identify potential issues before they impact your users.

To ensure the validity and accuracy of your API data, Sematext offers API data validation capabilities. You can monitor API calls and validate the structure and content of the responses, ensuring that the data returned is correct and meets your expectations. This is particularly useful for verifying the integrity of data coming from external APIs or critical endpoints.

One of the key benefits of Sematext is its ability to configure alerts based on response time thresholds. You can define specific thresholds that, when exceeded, trigger alerts to notify you of potential performance issues. These alerts can be sent through various channels such as email, Slack, or PagerDuty, ensuring timely notifications and prompt action..

Start your 14-day free trial today and experience the power of a comprehensive API monitoring solution to optimize your performance and enhance user experience.

Start Free Trial

See Also