Website performance, made clear.

Run a real-browser speed test, understand what slows the page down, and leave with evidence you can act on.

New analysis

Test a website

Test type

Start a Site Performance or...

Lighthouse
Visual Comparison

Test!

Enter URL to test

Simple Configuration 3 test runs from recommended location and browser presets

Run Carbon Control (Experimental: Measures carbon footprint. Chromium browsers only).

Include Repeat View (Loads the page, closes the browser and then loads the page again)

Run Lighthouse Audit (Runs on Chrome, emulated Moto G4 device, over simulated 3G Fast or 4G Fast connection)

Advanced Configuration Choose from all browser, location, & device options

Test Location

Browser 0 Pending Tests

Connection

BW Down	BW Up	Latency	Packet Loss
Kbps	Kbps	ms	%

Desktop Browser Dimensions
Number of Tests to Run
Repeat View First View and Repeat View First View Only
Label

Stop Test at Document Complete
Typically, tests run until all activity stops.
Ignore SSL Certificate Errors
e.g. Name mismatch, Self-signed certificates, etc.
Capture network packet trace (tcpdump)
Save response bodies
For text resources (HTML, CSS, etc.)
Preserve original User Agent string
Do not add PTST to the browser UA string
User Agent String
(Custom UA String)
Append to UA String
Disable AVIF image support
Firefox and Chromium-based browsers only
Disable WEBP image support
Firefox and Chromium-based browsers only
Capture Full Size Video
Enables full size screenshots in the filmstrip
Minimum test duration
Capture data for at least... seconds
Custom headers Add custom headers to all network requests emitted from the browser (type in or read from a text file)
Inject Script JavaScript to run after the document has started loading (type in or read from a text file)
Inject script into all frames and run before any page scripts run (Chrome-only)

Run Carbon Control (Experimental: Measures carbon footprint.)
Run Lighthouse Audit (Uses a "3G Fast" connection for mobile or "4G Fast" connection for desktop independent of test settings)
Capture Dev Tools Timeline
Enable v8 Sampling Profiler (much larger traces)
Capture V8 Runtime Call Stats
Capture Chrome Trace (about://tracing)
Trace Categories
(when tracing is enabled)
Capture Network Log
Enable Data Reduction
Chrome 34+ on Android
Use browser traffic shaping (enabled by default)
Host Resolver Rules
i.e. MAP * 1.2.3.4
Command-line
Custom options

HTTP Basic Authentication
Username
Password

PLEASE USE A TEST ACCOUNT! as your credentials may be available to anyone viewing the results.

Enter Script (or read it from a text file). Lighthouse does not perform per step reports for custom scripting, but will run a report on the final step

Script includes sensitive data
The script will be discarded and the HTTP headers will not be available in the results
Discard all HTTP headers

Check out the documentation for more information on this feature

Block Requests Containing (URL substrings)... Space-separated list (type in or read from a text file)

Block Domains (full host names)... Space-separated list of domains (type in or read from a text file)

Simulate failure of specified domains. This is done by re-routing all requests for the domains to blackhole.webpagetest.org which will silently drop all requests.

Hosts to fail (one host per line)... Type in or read from a text file

Custom Metrics: Type in or read from a text file

See the documentation for details on how to specify custom metrics to be captured.

List of URLs to test (one URL per line)... Type in or read from a text file

From numbers to next steps

Everything you need to find the slowdown.

Real experience

Test in a real browser with repeatable location, device and connection settings.

Visual evidence

See the page take shape with filmstrips and video alongside the performance timeline.

Deep diagnostics

Inspect DNS, TCP, TLS, requests and Core Web Vitals to pinpoint what needs attention.