Website is down
Uptime monitoring should catch the failed response quickly.
Synthetic Monitoring vs Uptime Monitoring: What Each One Actually Catches
Uptime monitoring and synthetic monitoring are related, but they answer different questions. Uptime monitoring asks whether a page or endpoint responds. Synthetic monitoring asks whether a user-like action or workflow still works — using a real browser to render the page, execute JavaScript, and verify the outcome.
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When a simple ping is enough — and when you need a simulated user.
Why the distinction matters
Teams often start with uptime monitoring because it is simple and useful. If a page is down, the business needs to know quickly. But many high-impact failures do not look like downtime. A login flow can fail, a checkout button can stop working, or an API-powered page can load without data.
That is where synthetic monitoring and journey monitoring become useful. They help verify that a customer can complete an action, not just reach a URL.
Synthetic monitoring vs uptime monitoring at a glance
Use uptime monitoring for availability coverage, then add journey checks where customer actions matter.
| Criteria | Uptime monitoring | Synthetic monitoring | NorthDuty angle |
|---|---|---|---|
| Primary question | Is the page or endpoint reachable? | Can a simulated user complete an action? | NorthDuty asks both: page reachable and healthy, and user journey completable. |
| What runs the check | Usually an HTTP ping or basic HTTP GET | A real browser that renders pages and executes JavaScript | NorthDuty uses Playwright + real Chromium for all checks — health and journeys alike. |
| Best for | Availability, SSL, DNS, redirects, and response timing | Login, signup, checkout, forms, and multi-step workflows | Teams that need both availability and customer-facing reliability. |
| Common gap | A page can return 200 OK while still being broken | Synthetic checks only cover the flows you script | NorthDuty pairs journeys with rendered health checks, so blank pages and script errors outside the flow are caught too. |
| Setup style | Usually a URL and alert destination | Usually steps, scripts, or a flow definition | NorthDuty suggests journeys with AI or lets teams write them in plain text. |
Examples of when each type helps
The right monitoring type depends on the failure mode you need to catch.
Checkout fails after cart
Synthetic or user journey monitoring is better because the failure appears several steps in.
A CTA disappears
A journey that clicks the CTA is needed because the page may still respond successfully.
The page loads with missing data
Website health and API call tracking help reveal failed dependencies behind the rendered page.
Best practices for combining both
Most important websites need layered monitoring, not a single check type.
- Use uptime monitoring on every business-critical route
- Add synthetic or journey monitoring to conversion and account-access flows
- Watch JavaScript errors and API calls on JavaScript-heavy pages
- Click the main CTA in a journey on pages where it drives conversion
- Keep alerts understandable for the people who need to respond
- Review monitoring depth whenever a page becomes more important to the business
Run the same ten failures past both kinds of check
The distinction is not which is better. It is which failures each one is physically capable of seeing.
| Failure | Uptime check | Synthetic journey |
|---|---|---|
| Server down, DNS failure, expired domain | Catches it | Catches it, more expensively |
| SSL certificate expired | Catches it as a failed request | Catches it |
| Page returns 200 but renders blank | Misses it — the status code is fine | Catches it |
| Add to cart does nothing | Misses it | Catches it |
| Checkout fails at the payment step | Misses it | Catches it, and names the step |
| Form submits but never delivers | Misses it | Catches it only if the journey checks the receiving end |
| Login broken for real accounts | Misses it | Catches it |
| Layout break that hides the CTA | Misses it | Catches it if the journey clicks the CTA |
| Site slow but working | Catches it as a response-time trend | Catches it, per step |
| A single region cannot reach you | Catches it, if you check from several locations | Catches it, at several times the cost |
Cost is why people pick one, and why picking one is a mistake
An uptime check is one HTTP request. It is cheap enough that checking every URL you own every minute is unremarkable, which is exactly why it became the default. A synthetic journey drives a real browser through a sequence of steps, which costs orders of magnitude more to run — Datadog, for instance, publishes browser tests at $12 per 1,000 runs against $5 per 10,000 API test runs, a 24x difference per execution.
That economics drives the right architecture rather than an either/or. Blanket the site with cheap uptime checks, because there is no reason not to. Then pick the handful of paths that actually carry money — checkout, signup, login, the main form — and run those as journeys at whatever interval you can justify.
The mistake is treating the cheap layer as sufficient because it is green. An uptime check cannot fail on a broken checkout; it does not know what a checkout is. Its silence is not evidence, and a site can be entirely unusable while every uptime check in the account reports 100%.
Conclusion
Uptime monitoring is the foundation. Synthetic monitoring is the next layer for customer actions. Website health checks close the gaps that both can miss alone.
NorthDuty runs all its checks — health checks and user journeys — in a real Chromium browser via Playwright. That means even the basic uptime check is synthetic: it renders the page, executes JavaScript, captures Core Web Vitals, detects blank screens, and intercepts API calls. Journey monitoring then extends that same browser to simulate multi-step flows, with AI-suggested journeys for teams that want monitoring without writing scripts.
Related NorthDuty Pages
Keep exploring the feature pages and commercial routes connected to this topic.
Feature
Uptime Monitoring
Monitor uptime every 5 minutes by default with HTTP, SSL, DNS, blank-page detection, broken resources, JavaScript errors, and API call tracking.
Explore Uptime MonitoringFeature
User Journey Monitoring
NorthDuty runs your checkout, signup, login and form flows in a real browser on a schedule and reports the exact step that failed, with a screenshot.
Explore User Journey MonitoringComparison
Uptrends Alternative
Uptrends competitors compared: NorthDuty, Checkly, Site24x7, Pingdom, Better Stack, UptimeRobot and Hyperping on transaction monitoring and 2026 pricing.
Compare UptrendsComparison
Checkly Alternative
Checkly alternatives compared: no-code journeys vs Playwright check runs, what run quotas mean in practice, and 2026 pricing for 5 alternatives.
Compare ChecklyPricing
Pricing
NorthDuty plans are sized by how many checkout, signup and login journeys you monitor: Free, $29 Starter, $79 Pro, $199 Business. 7-day trial, no card.
Compare pricing plansRelated reading
More NorthDuty guides on related website monitoring topics.
Article
How to Monitor Website Uptime
How to monitor website uptime properly: check intervals, locations, false alarms — and the failures that return HTTP 200 so uptime checks never see them.
Read How to Monitor Website UptimeArticle
Pingdom vs UptimeRobot
Compare Pingdom vs UptimeRobot and learn when businesses need deeper website health monitoring beyond basic uptime visibility.
Read Pingdom vs UptimeRobotArticle
Datadog vs Pingdom
Datadog vs Pingdom in 2026: Datadog's published per-run synthetic pricing, Pingdom's calculator-gated quote, and what a 5-minute browser check really costs.
Read Datadog vs PingdomFrequently Asked Questions
Short answers that summarize the practical takeaways from this guide.
Is synthetic monitoring the same as uptime monitoring?
No. An uptime check is a single request that reads the response code. A synthetic check drives a real browser through a sequence of steps and asserts on the result. An uptime check cannot fail on a broken checkout, because it never attempts one.
Why is synthetic monitoring more expensive?
It runs a real browser rather than sending a request. The gap shows in published pricing: Datadog lists browser tests at $12 per 1,000 runs against $5 per 10,000 API test runs — roughly 24x per execution. That is why the sensible pattern is cheap uptime checks everywhere plus journeys on the few paths that carry revenue.
Do I need both?
Almost always. Uptime checks are cheap enough to run on everything and catch the failures that announce themselves. Journeys are the only thing that catches a page which returns HTTP 200 while being unusable — and those are the failures that stay broken longest, because nothing alerts on them.
Is synthetic monitoring the same as uptime monitoring?
No. Uptime monitoring checks whether a page or endpoint responds, while synthetic monitoring uses a real browser to render pages and simulate user actions. NorthDuty uses real Chromium for all checks — even basic health checks are browser-rendered, not just pings.
Do I need synthetic monitoring if I already have uptime monitoring?
You likely do if important actions such as checkout, signup, login, or form submission can fail while the page still responds.
What does NorthDuty add beyond basic uptime monitoring?
NorthDuty uses a real Chromium browser for all health checks, capturing Core Web Vitals (FCP, LCP, CLS), blank-page detection, JavaScript errors, API call visibility, and SSL status in every run. On top of that, it adds AI-suggested or plain-text user journey monitoring, with a screenshot of every step.
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