Synthetic Monitoring vs. APM Stack Trace Tools

The complexity of an application’s digital architecture is increasing dramatically every day.  In an era of cloud infrastructure, the goal is to integrate all your web services into one place:  CDN, DNS, third-party API services, QA tools, analytics tools, and any other component you can think of, are working with each other to make your services function.  With so many components in place for an application to run, each one of these behaves like its own black box within your IT infrastructure. Due to this compartmentalization, the issues of performance bottlenecks and single points of failure arise.  So how do you deal with that?  Well, there are many DevOps and monitoring tools available in the market today, and we’ll talk about two of the most widely used – synthetic monitoring and APM stack trace tools.


Synthetic Monitoring Tools

External synthetic monitoring tools are intended to test external applications by emulating end users from external networks and locations.  User actions are simulated by scripting the paths that can be taken by the user throughout the application.  Synthetic monitoring gives useful information about uptime, functionality, and the general health of the critical transactions and steps users take in the application. This data gives you answers to the following important questions:

  1. Is my application up and running?
  2. Is my website speed good?
  3. Are my APIs in good health?
  4. Are all transactions working as expected?
  5. Are there any bottlenecks or failures within the infrastructure?
  6. Are all third-party services working as expected?
  7. What is the potential loss of revenue if a critical application fails?


APM Stack Trace Tools

APM stack trace tools are primarily used for discovering issues in the code by taking advantage of code-level monitoring and tracing. Applications are tested, not from the end user’s perspective, but from the perspective of back-end components.  APM stack trace tools provide useful information to developers and DevOps teams about internal infrastructure and code.  This information is used to optimize the code and performance in both development and production environments. APM stack trace tools help to answer these important questions:

  1. Is my code optimized?
  2. Are all functions working coherently?
  3. What are the function costs?
  4. Which exact line in your code throws the error in response?
  5. Who exactly is responsible for code failure – developers, DevOps team, or the network team?
  6. Is any internal API broken?


Synthetic Monitoring vs. APM Stack Trace Tools

Now that we’ve covered some of the basics of synthetic monitoring and APM stack trace tools, which one of these tools would you choose? Or would you use both? To answer these questions, you need to understand the differences between the two and their capabilities.



Synthetic monitoring simulates real users, and as a result, the data you get is from all the different layers in your architecture.  However, APM stack trace tools are insufficient in providing this data as they do the testing from a back-end (last mile) perspective.


Firewall – Inside and Outside

Synthetic monitoring can be scheduled to regularly monitor application, website, and network components from inside or from outside the firewall. This is a critical differentiator from what APM stack trace tools can do. This means you can detect issues such as DNS problems, third-party element issues, network connectivity issues, SLA (service level agreement) validations, and more.  APM stack trace tools live inside a firewall and cannot detect issues externally/outside your firewall. Your application could be working fine in a development or staging environment, but as soon as you push it into production, everything that can go wrong, goes wrong, and it could take quite a while to figure out what happened.  Synthetic monitoring can pinpoint where errors are occurring, so your teams can fix them fast, preventing users from being exposed to a faulty application and less than stellar experience.


User Experience

Synthetic monitoring is more about user experience. You get to know the overall architecture impact and experience your users are going to have.  APM stack trace tools are valuable in code-level monitoring and tracing, but prone to miss critical issues that can impact user experience resulting in user frustration and churning.


Geographical Monitoring

Synthetic monitoring tools can test your sites and applications from different global locations, as well as simulate network conditions that your users actually experience. Knowing where issues arise is necessary for quick detection and repair of issues to ensure availability across all service regions.  However, APM stack trace tools, will test your applications and sites through your production servers and load balancers to discover issues, which are limited to several back-end layers. Some vendors may give you an impression of geographical testing but that is limited to their cloud hosting provider’s regional capability. You will be able to optimize the traffic coming to your servers but you may fail to detect from which region your users may face outages.


Browser and Device-Specific Problems

Synthetic monitoring tools can simulate users using different desktop/mobile browsers and devices, so you get data about platform-specific problems, but you may not be able to easily pinpoint the exact issue, resulting in a longer time to resolution.  APM stack trace tools provide deeper information in the issue at code-level so you can easily identify the browser and device-related issues and resolve them quickly. These tools are a great asset if you have a wide demographic and concerned with platform-related performance.


Intermittent Problems

Your users can behave erratically, taking different paths before finally completing a transaction.  Even though external synthetic monitoring tools are great for allowing you to script user behavior and record and monitor those critical paths, it unfortunately cannot take into account every variable or action by a real user during a session, so it could potentially cause a monitoring blind spot if users take an unexpected path or action.  APM stack trace tools are great at providing all necessary information required to diagnose and repair an unforeseen issue that is faced by a real user, as it is usually associated with the back-end infrastructure of your application.



Now that you have got an overall idea of what a synthetic monitoring tool can do and what problems APM stack trace tools can solve, you can choose which one to use and when in your monitoring strategy.  To sum it up, synthetic monitoring allows you to foresee real-world problems and proactively resolve them before they affect your users. APM stack tracing tools, however, are valuable to monitor and trace code-level issues to improve and optimize your back-end infrastructure. Each one of these tools has it’s clear advantages and benefits.  If you are more concerned about overall user experience, you may want to implement a strategy that makes the best of both tools. Taking advantage of both tools will serve you well and improve the overall experience of your application resulting in better speed, availability, performance, and revenue growth.

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