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Synthetic monitoring

Synthetic monitoring: what it is, how it works and when to use it

Synthetic monitoring simulates a visitor at fixed intervals to check that your site responds and that key journeys work, even when nobody is using it. Here is how it works, how it differs from RUM and where to start.

Pathly dashboard showing the status of Ping, Flow and Chain

What is synthetic monitoring?

It is a way to watch a website with simulated visits. A robot repeats, at fixed intervals and from known locations, what a user would do: open a page, log in, add a product to the cart or call an API. If something breaks or slows down, an alert goes out. Because it does not depend on real traffic, it catches a failure in the middle of the night or right after a deployment, before the first customer arrives. You will also see it called synthetic testing or synthetic transaction monitoring: the idea is the same.

The three types of synthetic tests

An HTTP check requests a URL and verifies the status code, response time, TLS certificate and an expected piece of text: it is fast and enough to know whether the site is up. A browser journey loads pages in a real browser, clicks and fills in forms step by step, like a visitor: it is the only way to see a broken button or failing JavaScript. An API chain links several calls, such as a login followed by a protected route, passing the token from one to the next. In Pathly they are called Ping, Flow and Chain.

Synthetic monitoring vs RUM: two different questions

RUM (Real User Monitoring) measures what real visitors experience, through a script installed on your pages. Synthetic monitoring needs no traffic and adds nothing to the site: it checks that a specific journey works right now. RUM helps you understand real-world performance. Synthetic monitoring tells you about an outage before your customers do. Many teams use both.

When it is worth it

When a journey brings in revenue or leads, such as checkout, login or a quote form. When traffic is low or irregular and an outage could go unnoticed for hours. When you ship changes often and want to check the site right after each release. Or when you look after client websites and need dated proof that everything worked.

Getting started with Pathly

Start with the free audit: in about 30 seconds and without an account, it checks response time, TLS certificate, broken links and security headers from Europe. Then create a Ping on your home page and record, without code, the journey that matters most so that Flow replays it. The Solo plan is free and needs no credit card.

Ping, Flow and Chain: what each one checks

TestWhat it checksWhen to use it
Ping (HTTP)Status code, response time, TLS and expected textKnowing whether the site responds, every few minutes
Flow (browser)A full journey in a real Chrome, with a screenshot of the step that failsCheckout, login, forms
Chain (API)Several chained HTTP calls that pass values from one to the nextAuthenticated APIs behind the site

Synthetic monitoring: frequently asked questions

Is synthetic monitoring the same as synthetic testing?
In practice, yes. Synthetic testing often means running scripted checks once, for example in a test pipeline, while synthetic monitoring runs them continuously against the live site. Both rely on automated visits that simulate a user to check that a site responds and that its journeys work.
What is the difference between synthetic monitoring and uptime monitoring?
Uptime monitoring is the simplest form of synthetic monitoring: an HTTP check that tells you whether the site responds. Synthetic monitoring goes further when it walks through pages in a real browser or chains calls to an API.
Do I need to know how to code?
Not with Pathly. Flow journeys are recorded by clicking through your own site, without writing scripts. Ping and Chain checks are set up from a form.
Where do the tests run from?
From Europe, on Google Cloud (europe-west1 region). Pathly applies the GDPR and offers its customers a data processing agreement (DPA).
How much does it cost?
The audit is free and needs no account. The Solo plan is free too, with no credit card, and includes Ping checks and one Flow a day. Paid plans add more checks, more frequent Flow runs, shorter intervals and alerts in Slack or Teams. Prices are on the pricing page.

Further reading

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