Is your website
fast enough?

Overview

Velox uses the Google PageSpeed Insights API v5, which runs Google Lighthouse in a controlled datacenter environment. Results are lab data — consistent and reproducible, but not identical to real user experience. The CrUX tab shows real user data separately.

The 7 Report Tabs

Summary

High-level overview: speed visualization timeline, top issues ranked by impact, page size breakdown by resource type, and request count summary. Start here to get oriented.

Performance

All 17+ performance metrics in full detail — from TTFB to Fully Loaded Time, with thresholds and bar charts. This is your stopwatch.

Structure

Prioritized audit list of structural issues — the "instruction manual" for improving performance. Each audit shows impact (High/Medium/Low/Pass) and a description of what to fix.

CrUX

Chrome User Experience Report data — anonymized measurements from real Chrome users visiting your site. Shows distribution of Good / Needs Improvement / Poor for LCP, CLS, FCP, and INP. Only available for URLs with enough traffic in Google's dataset.

Waterfall

Every network request in chronological order with type-colored bars. Bar position = when the request started. Bar width = how long it took. Use this to spot render-blocking resources, slow third parties, and sequential request chains.

Resources

All network requests grouped with transfer size, resource type, and proportional size bars. Identify which resources contribute most to page weight.

History

Every audit you run is saved in your browser (localStorage). Track performance over time, see when grades change, and spot regressions after deploys.

Scoring

Performance Score (0–100)

Weighted aggregate of 6 Lighthouse metrics:

• Total Blocking Time — 30%
• Largest Contentful Paint — 25%
• Cumulative Layout Shift — 15%
• First Contentful Paint — 10%
• Speed Index — 10%
• Time to Interactive — 10%

Structure Score (0–100)

Average of all structural audit scores. Measures how well the page is built, independent of network conditions. Improving structure generally improves performance too.

GTmetrix Grade (A–F)

A = 90–100, B = 75–89, C = 60–74, D = 45–59, E = 30–44, F = 0–29.

Core Web Vitals thresholds

Metric	Good	Needs Improvement	Poor
LCP	≤ 2.5s	2.5–4s	> 4s
CLS	≤ 0.1	0.1–0.25	> 0.25
FCP	≤ 1.8s	1.8–3s	> 3s
TBT	≤ 200ms	200–600ms	> 600ms
TTI	≤ 3.8s	3.8–7.3s	> 7.3s
SI	≤ 3.4s	3.4–5.8s	> 5.8s

Mobile vs Desktop

Mobile: Simulates a Moto G4 with 4x CPU throttling and Slow 4G network (150ms RTT, 1.6 Mbps down). Scores will be significantly lower than desktop. This is what most of your real users experience.

Desktop: No CPU throttling, fast cable connection. Use to diagnose JS execution and rendering issues without network noise.

Endpoint

GET https://www.googleapis.com/pagespeedonline/v5/runPagespeed

Parameters

Parameter	Required	Values
url	Yes	Full URL including https://
strategy	No	mobile (default) · desktop
category	No	performance · accessibility · seo · best-practices
key	Recommended	Your Google API key

JavaScript example

const url = 'https://example.com';
const key = 'YOUR_API_KEY';
const strategy = 'mobile'; // or 'desktop'

const res = await fetch(
  `https://www.googleapis.com/pagespeedonline/v5/runPagespeed` +
  `?url=${encodeURIComponent(url)}&strategy=${strategy}` +
  `&category=performance&key=${key}`
);
const data = await res.json();

const lhr = data.lighthouseResult;
const score = Math.round(lhr.categories.performance.score * 100);
const lcp   = lhr.audits['largest-contentful-paint'].numericValue;
const cls   = lhr.audits['cumulative-layout-shift'].numericValue;
const tbt   = lhr.audits['total-blocking-time'].numericValue;

console.log(`Score: ${score}/100`);
console.log(`LCP: ${(lcp/1000).toFixed(2)}s`);
console.log(`CLS: ${cls.toFixed(3)}`);
console.log(`TBT: ${Math.round(tbt)}ms`);

CI/CD — fail build on regression

#!/bin/bash
# velox-check.sh — add to your GitHub Actions or deploy hook

SCORE=$(curl -s \
  "https://www.googleapis.com/pagespeedonline/v5/runPagespeed\
?url=https://yoursite.com&strategy=mobile\
&category=performance&key=$PSI_KEY" \
  | python3 -c "
import sys, json
d = json.load(sys.stdin)
print(int(d['lighthouseResult']['categories']['performance']['score']*100))
")

echo "Performance score: $SCORE"
[ "$SCORE" -lt 75 ] && echo "❌ Score below 75. Blocking." && exit 1
echo "✅ Score OK."

Getting a free API key

1. Visit console.cloud.google.com and create a project
2. Enable the PageSpeed Insights API
3. Credentials → Create Credentials → API Key
4. Restrict the key to PageSpeed Insights API for security

What we collect

Velox does not create accounts, store passwords, or track individuals. The only data involved:

• The URL you enter — sent to Google's PageSpeed Insights API. We do not log or store it server-side.
• Your audit history — stored entirely in your own browser's localStorage. Never sent to any server. You can clear it anytime.
• Browser telemetry — IP address and user-agent sent by your browser to our CDN. Not linked to any identity, not retained beyond 24 hours.

Google PageSpeed Insights

Audit requests are processed by Google. Google's Privacy Policy applies to those requests. We receive the API response in your browser only — it's never forwarded to our servers.

Cookies

No tracking cookies. No advertising cookies. No analytics. The only browser storage is localStorage for your audit history — client-side only, never transmitted.

Third parties

Google Fonts (fonts.googleapis.com) for typography. No ad networks, no tracking pixels, no social widgets.

Contact

Questions: privacy@velox.dev

1. Service

Velox is a free web performance analysis tool. It sends URLs you provide to Google's PageSpeed Insights API and presents results. Provided "as is" with no warranty of uptime or accuracy.

2. Acceptable use

You may analyze URLs you own or have permission to test. You may not use Velox to:

• Perform denial-of-service attacks or load test servers
• Scan for security vulnerabilities
• Automate bulk requests that violate Google's API Terms of Service
• Resell or mirror output without attribution

3. API keys

If you supply a Google API key, you are responsible for its security and any usage costs beyond Google's free tier.

4. Limitation of liability

Velox is not liable for decisions made based on its reports. Scores are lab-based and may differ from real user experience. Always validate with real user monitoring before major infrastructure decisions.

5. Changes

We may update these terms. Continued use constitutes acceptance. Contact: legal@velox.dev

Uptime — last 30 days

Known limitations

• The keyless API endpoint shares quota globally — use your own key to avoid quota errors.
• Sites behind Cloudflare Bot Fight Mode, login walls, or private networks cannot be audited.
• Very large SPAs may time out on Lighthouse. Try auditing a specific deep-link page.
• CrUX data is only available for URLs with sufficient Chrome traffic in Google's dataset.
• Video playback of page load requires a server-side browser runner — not available in this client-only tool.

Incidents

✓ No incidents in the last 30 days.