Will your store survive Black Friday?
UserLimit sends simulated shoppers through your store in real browsers, so you see what breaks while there is still time to fix it.
Simulation: a store under Black Friday traffic
Classic Tee
Service Unavailable.
An illustration, not a measurement. Drag the slider, then click Add to cart and Checkout as the crowd grows.
A sale does not stress one page. It stresses the whole visit.
Each step asks something different of your servers, and the slow, shared parts give way first.
Search
Every query hits your catalogue, often through a separate search service. It can time out while the rest of the site still looks fine.
Product page
Images, reviews and tracking scripts load for every visitor. A real browser loads them too, so you see how late the main image appears.
- Usually first to fail
Add to cart
The first write: a session, a stock check, a price rule. It breaks when many shoppers click at once, and the error they see is rarely the real one.
Checkout
Shipping, tax and payment are other people's services, with their own limits. Test up to the payment step, on a staging copy.
Size a Black Friday test for your store
Test 300 shoppers arriving at your busiest, each staying 30 s.
Not “it was slow”, but which step, and why
- 1
Every step, timed
The search that slows down is its own line, not part of an average.
- 2
Every failure, with its status code
And the step that hit it, so you know what to fix first.
- 3
Web Vitals per page
Rated against web.dev's limits, as a shopper's browser sees them.
Every run keeps its results and settings, so a fix can be compared with the run before it. A public link shares the result with your developers, agency or client.
Your first test, in three steps.
Sign up with no card and nothing to install. Pick a quiet day, and you will know how your store holds up before lunch.
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01
Verify your store
Add a DNS record or a meta tag to prove the domain is yours. Tests only ever go to stores you have verified.
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02
Describe a visit
Pick a ready-made scenario or let the AI write one for your store, then choose how many shoppers to send.
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03
Read the result
Which step slowed down, which requests failed, and at how many shoppers. Fix it, rerun, compare.
Then make it a habit: schedule a daily run until Black Friday, with alerts to e-mail, Slack or a webhook, so a slow deploy shows up the morning after. The launch readiness guide has the full plan.
FAQs
How many concurrent users can my website handle?
There is no universal number: it depends on your platform, hosting, caching and what visitors do. A load test finds it for your store. Raise the number of sessions in steps (for example 100, 300, then 600) and note where page load times climb or sessions start to fail. That point, not the average, is your limit.
Is it safe to run a load test on my store?
You stay in control. Tests only go to domains you have verified with a DNS TXT record or a meta tag, the run stops on its own when too many sessions fail, and accounts start with a limit of 200 sessions at once. Use a staging copy where you can, and stop the scenario before the payment step so no real orders are placed.
How do I test an ecommerce website?
Test the path a shopper takes, not a single URL: land on a category, open a product, search, add to cart. Run it against a staging copy that mirrors production, start with a small baseline, then increase traffic to your expected peak and beyond. Leave payments and real orders out of the test.
Why do online stores crash on Black Friday?
Traffic arrives in a spike rather than evenly, and the slowest shared parts give way first: product search, the cart, the database behind them, and third-party scripts such as payments, reviews and tracking. A spike-shaped test shows which one it is before customers do.
What is the difference between load testing and stress testing?
Load testing checks that the site holds up at the traffic you expect. Stress testing pushes past that to find where it breaks. Both use the same method: a scenario, a number of sessions, a start-time spread, and a stop condition such as an error threshold.
Can I perform online load testing on my website?
Yes. UserLimit runs the test from the cloud, so nothing is installed on your side. You verify that you own the domain with a DNS TXT record or a meta tag, describe a visit as a browser scenario, and choose how many sessions to run.
How many users can a server handle?
It varies with the hardware, the application and how heavy each visit is. Measure it instead of estimating: run sessions that do what real visitors do and watch load times and failed requests as the traffic grows.
Does UserLimit test the checkout and payment?
No. Scenarios cover browsing, search and add-to-cart on a site you have verified, and we recommend a staging environment. Payments, real orders and emails need separate arrangements, so stop the scenario before the payment step.
Does UserLimit test APIs?
No. Sessions run in real browsers from supported Playwright source, so UserLimit measures what visitors experience in the page. It does not offer API-only load testing.
Find yours on a quiet Tuesday, not on Black Friday
Start free and run your first test in a few minutes.