--- title: "Evaluat: Real-Browser Performance Testing with Core Web Vitals" description: "Evaluat is a real-browser performance testing platform: Core Web Vitals under load, plus session video, network logs, and console logs for every virtual user." url: "https://www.evaluat.xyz/" last_modified: "2026-11-06" --- REAL-BROWSER PERFORMANCE TESTING # Slow pages lose sales. Find yours before your customers do. Your busiest day, rehearsed in real browsers before it happens. You read the verdict; your engineers get the report. [Book a demo](https://www.evaluat.xyz/demo?intent=performance) [Run a free speed test](https://www.evaluat.xyz/tools/website-speed-test) Teams we've worked with - ![Auping](https://www.evaluat.xyz/logos/auping.svg) - ![terStal](https://www.evaluat.xyz/logos/terstal.svg) - ![roadmap.sh](https://www.evaluat.xyz/logos/roadmap-sh.svg) - ![Tablething](https://www.evaluat.xyz/logos/tablething.svg) What slow costs ## Where slow pages cost you money. A minute of your busiest sale is worth more than a minute of any other day, and most teams have never put a figure on it. Set up the sale you are worried about. The downtime cost calculator is interactive. Open in a browser to use it. That is what half an hour costs you, and it assumes the site actually went down. Usually it does not. It stays up and slows to a crawl at checkout, shedding the same orders without ever registering as an outage. Hard down is a hosting problem. Slow under load is the one a performance test finds, and it is the more common of the two. Most load testing tools just ask your server if it answered. Evaluat opens your shop in many real browsers at your forecast peak, like real customers on real laptops, and watches what they actually see. ### Checkout at peak A checkout that slows under peak traffic sheds buyers at the exact moment you have the most of them. Evaluat rehearses your checkout at Black Friday numbers in real browsers and shows the point where it starts to drag. [More on checkout under load](https://www.evaluat.xyz/use-cases/checkout-performance-testing). ### The surge, not the average The email goes out, or the spot airs, and everyone arrives in the same five minutes. That shape breaks sites that handle a busy day fine. Rehearse the surge, not just the volume. [More on peak readiness](https://www.evaluat.xyz/use-cases/peak-readiness). ### The third-party tax Analytics, reviews, chat, A/B tests. Each tag is small; together they tax every page view. The report shows which one costs you the most, so you can decide whether it earns its keep. ### Speed and search Google uses field page-experience signals, including [Core Web Vitals](https://www.evaluat.xyz/blog/core-web-vitals-load-testing), among other ranking factors. Evaluat measures related diagnostics under controlled load, so you can find and fix the slow pages that fight uphill for the traffic you don't pay for. Teams run the same rehearsals for capacity planning, release validation, regional comparisons, and forensic debugging. Running a store? Start with [ecommerce performance testing](https://www.evaluat.xyz/solutions/ecommerce-performance-testing). [How the testing works](https://www.evaluat.xyz/how-it-works) The report · one real run ## A verdict you can read. Evidence your engineers can act on. > "The site stayed up and served every request under 200 users, but pages loaded far too slowly and about 1 in 10 shopper journeys did not finish." > > The opening line of this run's Executive Report. Written by the platform, in plain language. ### Written for the meeting, not the war room. A health score, findings ranked by severity, and recommended fixes in plain language. Forward it as it is. [What's in a report](https://www.evaluat.xyz/reports/examples) ![Evaluat verdict banner: the site stayed up under 200 users but pages loaded far too slowly, with an Apdex of 0.79, health score 0.62, 200 peak users, a 0% error rate, and 35,925 requests.](https://www.evaluat.xyz/_astro/exec-summary-verdict.BY85lhUn_1BkEhp.webp) ### A failure at peak isn't a percentile. It's a session. Open the session. Watch the moment it broke. The video, the network log, and the console output are there for every virtual user. [How session video works](https://www.evaluat.xyz/how-it-works#session-recording) ![Evaluat failed session 178.40: status Failed, a 2 minute 8 second duration, the scenario it ran, and the element-not-visible selector error that stopped the journey.](https://www.evaluat.xyz/_astro/session-detail-top.k6S18gqz_Z1zlkSR.webp) Session 178.40: the step that failed and the selector that timed out. Working with us ## Three steps to a straight answer. 1. step 1 of 3 ### Build the journey once. On the demo call we assemble your real journeys in the visual editor: home, product, cart, checkout. No scripts, no code. 2. step 2 of 3 ### Run it at your peak. Real browsers walk those journeys at your forecast traffic, from the UK and the EU, while everything is recorded. 3. step 3 of 3 ### Read the verdict. Hand off the evidence. You see what held, what slowed, and what broke. Your engineers open the exact sessions behind each finding. Who reads what ## One report. Three readers. ### [For the CEO](https://www.evaluat.xyz/reports/examples) [A plain-language verdict you can read on the way into the meeting, and what to fix first.](https://www.evaluat.xyz/reports/examples) [Tour a real report](https://www.evaluat.xyz/reports/examples) ### [For the CMO](https://www.evaluat.xyz/solutions/ecommerce-performance-testing) [Proof the landing page holds at campaign traffic before the spend goes out.](https://www.evaluat.xyz/solutions/ecommerce-performance-testing) [Ecommerce performance testing](https://www.evaluat.xyz/solutions/ecommerce-performance-testing) ### [For the engineering lead](https://www.evaluat.xyz/#engineering) [The deep half of this page is yours: what gets captured on every run, and how to check our work.](https://www.evaluat.xyz/#engineering) [Skip to the engineering section](https://www.evaluat.xyz/#engineering) For your engineers ## The part your engineering lead will check. Configured once at the project level. Captured for every virtual user. Open any session and see exactly what happened. This is the half your engineering lead will want. The full mechanics, including datasets, popup handlers, and regional execution, are on [How it works](https://www.evaluat.xyz/how-it-works); it's written for them. ### Test Scenarios - Build a journey once. Reuse it everywhere. - Step-by-step playback with pass/fail per step. [How scenarios work](https://www.evaluat.xyz/how-it-works#scenarios) ### Core Web Vitals capture - LCP, INP, and CLS for every virtual user, plus FCP. - Aggregated by run, addressable per session and URL. [How Vitals are captured](https://www.evaluat.xyz/how-it-works#vitals) ### Session Video - Watch any virtual user's browser end-to-end. - Step playback timestamped to the millisecond. [How session video works](https://www.evaluat.xyz/how-it-works#session-recording) ### Network & Console Logs - Every request and every console message, per user. - Searchable and deduplicated across the whole run. [How log capture works](https://www.evaluat.xyz/how-it-works#network) ### Five views on the same run. Report views. Pick one to see that view of the run. Overview URLs Performance Sessions Console Logs Network Logs ![Evaluat report Overview: test execution details, an Apdex of 0.79, 200 peak users, a 0% error rate, and the user ramp curve across the run, from a 200-user peak-trading rehearsal.](https://www.evaluat.xyz/_astro/overview-panel.CnpqSP8l_2cx7ce.webp) ![Evaluat URLs Performance view: per-URL hit counts, status codes, and Core Web Vitals including LCP, CLS, and INP, from a 200-user peak-trading rehearsal.](https://www.evaluat.xyz/_astro/urls-performance-panel.D8zIljEo_2bzPRA.webp) Every URL in the journey broken out, so you can see exactly which step slowed down under load. ![Evaluat Sessions view: every virtual user's session listed with start time, duration, scenario, and pass or fail status, from a 200-user peak-trading rehearsal.](https://www.evaluat.xyz/_astro/sessions-list-panel.CJ5COGIn_2iIi1J.webp) A recorded session for every virtual user, so you can watch the exact run that failed instead of inferring it from an average. ![Evaluat Console Logs view: browser console warnings and messages deduplicated with a count for each across the whole run, from a 200-user peak-trading rehearsal.](https://www.evaluat.xyz/_astro/console-logs-panel.Gv4SK4x9_Z1vETcc.webp) The browser console output captured per session, errors and warnings included. ![Evaluat Network Logs view: every HTTP request with its page URL, hit count, status, and p95 duration, from a 200-user peak-trading rehearsal.](https://www.evaluat.xyz/_astro/network-logs-panel.Dw6i6Q32_q9Ikf.webp) The network activity captured per session, so you can see what was slow or failing on the wire. Evaluat is agent-ready: your team's AI agents can run a real-browser speed test over the Model Context Protocol and read the results back, no API key needed. [Developer and agent reference](https://www.evaluat.xyz/developers) The lineup ## One platform. Three products. Build a scenario once for Performance Testing. Testing Suite, now in early access, re-runs the same scenarios as post-deploy smoke checks. Monitoring is planned and will run them around the clock. One definition, one place to maintain it. ### [Performance Testing](https://www.evaluat.xyz/product/performance-testing) [Real-browser performance tests at your forecast peak. Track Core Web Vitals per session and per URL. Find what breaks before peak does.](https://www.evaluat.xyz/product/performance-testing) [See Performance Testing](https://www.evaluat.xyz/product/performance-testing) ### [Testing Suite Early access](https://www.evaluat.xyz/product/testing-suite) [Re-run the same scenarios as post-deploy smoke checks. See which journeys failed and where, with session video and logs to fix what broke.](https://www.evaluat.xyz/product/testing-suite) [See Testing Suite](https://www.evaluat.xyz/product/testing-suite) ### [Monitoring Planned](https://www.evaluat.xyz/product/monitoring) [Will run your scenarios around the clock from the UK and the EU and alert on Web Vitals regressions, with session video to debug them.](https://www.evaluat.xyz/product/monitoring) [See Monitoring](https://www.evaluat.xyz/product/monitoring) Keep reading ## Latest from the blog. Guides and engineering notes on performance testing, Core Web Vitals, and peak readiness, for the person who owns the site and the engineer who fixes it. - [![A timeline from 4 November to Black Friday on 27 November 2026, split into two windows. From 4 to 13 November, about eight working days, small changes can still land. From the freeze on 13 November to Black Friday, two weeks are for checks that only look and for watching. Enough time to check, not enough to rebuild.](https://www.evaluat.xyz/blog/black-friday-performance-checklist-cover.svg)](https://www.evaluat.xyz/blog/black-friday-performance-checklist) ### [The last-minute Black Friday performance checklist](https://www.evaluat.xyz/blog/black-friday-performance-checklist) [Black Friday 2026 is on 27 November, 23 days after this post. If you have not prepared, that is too little time to rebuild anything and enough to find what would break. These ten checks still fit. Most of them only look at your site, and the few that change it should land before your code freeze.](https://www.evaluat.xyz/blog/black-friday-performance-checklist) [Ahmad Farzan · 4 November 2026](https://www.evaluat.xyz/blog/black-friday-performance-checklist) - [![The browser's main thread drawn as one bar shared by several owners. The site's own code takes the first part. Tag manager tags, a chat widget, a video embed and ads, all code from other companies, take the rest. A shopper's tap has to wait until the thread is free. You wrote some of the page; your shoppers wait for all of it.](https://www.evaluat.xyz/blog/third-party-scripts-performance-cover.svg)](https://www.evaluat.xyz/blog/third-party-scripts-performance) ### [Third-party scripts and tag managers: the slowdown you did not write](https://www.evaluat.xyz/blog/third-party-scripts-performance) [Nine in ten web pages run code from another company's servers, such as analytics, ads, chat and consent banners. Each one downloads, runs on the main thread beside your own code, and can hold the page up when its server is slow. A tag manager makes them easy to add. Measuring what each one costs tells you which to keep.](https://www.evaluat.xyz/blog/third-party-scripts-performance) [Ahmad Farzan · 29 October 2026](https://www.evaluat.xyz/blog/third-party-scripts-performance) - [![A virtual waiting room drawn as a queue, a gate and a shop. On the left, a crowd of shoppers waits in the queue. In the middle, the gate lets them in at 150 a minute. On the right, the site holds 900 shoppers at once and stays fast for everyone inside. The queue is the easy part; the number at the gate has to be measured.](https://www.evaluat.xyz/blog/product-drop-queues-waiting-rooms-cover.svg)](https://www.evaluat.xyz/blog/product-drop-queues-waiting-rooms) ### [What is a virtual waiting room?](https://www.evaluat.xyz/blog/product-drop-queues-waiting-rooms) [A virtual waiting room is a holding page in front of a website that lets visitors in at a rate the site can serve and queues everyone else, so a busy sale becomes a wait instead of a crash. Installing one is the easy part. Choosing how many shoppers it lets in is the hard part, and that number has to be measured.](https://www.evaluat.xyz/blog/product-drop-queues-waiting-rooms) [Ahmad Farzan · 28 October 2026](https://www.evaluat.xyz/blog/product-drop-queues-waiting-rooms) - [![Five cache layers between a shopper and the database, drawn left to right: browser cache, CDN, full-page cache, object cache and database memory. A request for a product page is answered by the full-page cache and stops there. A basket request uses the browser cache for files only, skips the CDN page cache and the full-page cache, and goes on to the object cache and the database.](https://www.evaluat.xyz/blog/caching-explained-cover.svg)](https://www.evaluat.xyz/blog/caching-explained) ### [Caching explained: browser, CDN, full-page and object caches](https://www.evaluat.xyz/blog/caching-explained) [Caching means keeping a copy of something expensive to produce so the next request can be answered faster. A busy online shop has five layers of it between a shopper and the database. Basket, checkout and account requests skip the two layers that store whole pages, which is why they slow first under load.](https://www.evaluat.xyz/blog/caching-explained) [Ahmad Farzan · 22 October 2026](https://www.evaluat.xyz/blog/caching-explained) - [![The five stages a busy website fails in, drawn as a descending staircase. First, requests queue and pages slow. Second, timeouts turn slow requests into 502 and 504 errors. Third, retries and refreshes multiply the load. Fourth, overloaded servers miss health checks and are pulled from service. Fifth, the failure cascades to the next part of the system, often the database. The order barely changes; what runs out first does.](https://www.evaluat.xyz/blog/why-websites-crash-under-high-traffic-cover.svg)](https://www.evaluat.xyz/blog/why-websites-crash-under-high-traffic) ### [Why websites crash under high traffic](https://www.evaluat.xyz/blog/why-websites-crash-under-high-traffic) [Most websites do not simply switch off when traffic spikes. Requests queue for a limited resource, pages slow, timeouts turn slow into failed, and retries and failed health checks pile on more load until the site falls over. The symptoms arrive in roughly that order every time. What differs is which part runs out first.](https://www.evaluat.xyz/blog/why-websites-crash-under-high-traffic) [Ahmad Farzan · 21 October 2026](https://www.evaluat.xyz/blog/why-websites-crash-under-high-traffic) - [![A CDN receives 2,000 requests a second. Bars show how many reach the origin server at each cache hit ratio: 400 a second at 80 percent, 200 at 90 percent, 100 at 95 percent and 20 at 99 percent. Dropping from a 95 to a 90 percent hit ratio doubles the origin's traffic, and baskets, checkouts and orders are always among the requests that get through.](https://www.evaluat.xyz/blog/what-is-a-cdn-cover.svg)](https://www.evaluat.xyz/blog/what-is-a-cdn) ### [What a CDN does (and does not) do for your site under load](https://www.evaluat.xyz/blog/what-is-a-cdn) [A content delivery network (CDN) is a network of servers that keeps copies of your files close to your visitors and answers for your own server whenever it can. Under load it can absorb most requests for pages and files that are the same for everyone. Baskets, checkouts and every order still reach your server.](https://www.evaluat.xyz/blog/what-is-a-cdn) [Ahmad Farzan · 19 October 2026](https://www.evaluat.xyz/blog/what-is-a-cdn) [All posts](https://www.evaluat.xyz/blog) Common questions ## Questions we get asked. ### What is Evaluat? Evaluat is a real-browser performance testing platform. Every virtual user runs in its own isolated browser instance, so you capture Core Web Vitals (LCP, INP, CLS) and Navigation Timing under load, plus full session video, network logs, and console logs for every user. ### Do I need to be technical to use Evaluat? Mostly no. Reports are written in plain language for non-technical readers, and you can generate an Executive Summary when you need the verdict fast. Building a scenario happens in a visual step editor with no scripts; the one technical bit is pointing steps at the right elements with CSS selectors, which is a job for your developer or your agency. The deeper views (session video, network logs, console logs) are there for them when something needs fixing. ### How do I know if we need load testing? Three common signals. A date is coming when traffic multiplies (Black Friday, a product drop, a press or TV moment). You are changing platform, theme, or checkout. Or the site already feels slower during promotions than on a quiet Tuesday. If any of those apply, one rehearsal will tell you where you stand. ### What's in a test report? Five detail views: Overview (aggregate Web Vitals, time-series), URL performance (every URL with its own metrics), Sessions (every virtual user, individually addressable, with video), Console logs (deduplicated and counted), Network logs (every HTTP request, searchable across the run). You can generate an Executive Summary on top: a plain-language verdict with a health score, the key findings ranked by severity, and recommended fixes. [See what a report contains](https://www.evaluat.xyz/reports/examples). ### How does Evaluat differ from k6? k6 sends HTTP requests and measures how fast your server responds. Evaluat runs real browsers and measures what users actually see: Core Web Vitals (LCP, INP, CLS), plus FCP and the full network and console for every session. Use k6 for API load tests. Use Evaluat for the customer-facing parts of your app. [See all comparisons](https://www.evaluat.xyz/vs). ### Can Evaluat tell me if my site is ready for Black Friday? Yes. A Black Friday rehearsal is the most common first test. It runs your real journeys (home, product, cart, checkout) at the number of concurrent visitors you expect at peak. You can generate an Executive Summary for the verdict, and the session-level detail shows your team which step and which request slowed. Black Friday falls in late November, the day after US Thanksgiving. Fixes need time to ship, so the useful testing window closes earlier than it feels. ### Is there a free trial? We don't run a self-serve trial. Every onboarding includes a 30-minute demo on your real site, with a small test run live. The report from that demo is yours to keep, whether you go ahead or not. More answers on the [FAQ page](https://www.evaluat.xyz/faq). Get a demo Test in real browsers.\ Debug in real sessions. ## Know before your next peak. See it run on your site. 30 minutes, no slides. We run a small test on your real site, a handful of users, and the report is yours to keep either way. [Book a demo](https://www.evaluat.xyz/demo?intent=performance) [See how it works](https://www.evaluat.xyz/how-it-works)