Page speed,
in one report.
Choose mobile or desktop for each run. Inspect the Lighthouse performance score, available lab metrics, diagnostics, and ranked optimization opportunities.
How we compare
Same Lighthouse engine. Faster, broader, with monitoring.
| Feature | CheckFast | GTmetrix | PageSpeed | WebPageTest |
|---|---|---|---|---|
| Lighthouse performance score | ||||
| Mobile + desktop strategy selector | ||||
| Real-user CrUX field data in this tool | ||||
| Accessibility / Best Practices / SEO in this tool | ||||
| Page weight breakdown in this tool | ||||
| Top 5 opportunities sorted by impact | all | all | all | |
| Filmstrip / video | ||||
| Test from multiple locations | ||||
| Published report-time SLA | ||||
| Automatic permanent report | ||||
| Public API | paid | paid | ||
| Score monitoring + alerts | $9/mo | $15/mo |
Every metric that matters
A bounded, selected-strategy view of the Lighthouse performance category.
Mobile or desktop per run
Choose the Lighthouse strategy before each check and compare separate mobile and desktop runs when needed.
Lighthouse lab result
One performance-category PageSpeed Insights response for the strategy selected in the form.
Performance metrics
LCP, CLS, FCP, TTFB, TBT and Speed Index are rated when PageSpeed Insights supplies them.
Diagnostic context
See failing Lighthouse table and list diagnostics from the selected performance audit.
Machine-readable API
Use the same selected-strategy performance result through the authenticated or rate-limited public API.
Top optimization opportunities
Lighthouse's top 5 actionable opportunities ranked by potential time saved, with descriptions.
Explicit result scope
Results belong to the current request; the interactive check does not silently publish a permanent full report.
Performance monitoring
Track the aggregate Performance score and alert when it drops below the configured threshold.
Block PRs that hurt LCP.
Drop a curl into your CI to fail PRs that drop performance below your threshold or push LCP past 2.5s. Catch regressions before deploy, not after.
#!/usr/bin/env bash
SCORE=$(curl -sS -X POST \
https://checkfast.io/api/v1/speed/check \
-H "Content-Type: application/json" \
-d "{\"url\":\"https://staging.acme.com\"}" \
| jq .performanceScore)
if (( SCORE < 90 )); then
echo "Performance $SCORE < 90 — blocking deploy"
exit 1
fi
echo "Performance $SCORE — OK"Frequently asked questions
A mobile or desktop Lighthouse Performance score selected per run plus available lab metrics such as LCP CLS FCP TTFB TBT and Speed Index ranked opportunities and diagnostic context. The interactive API requests only the performance category; it does not return CrUX accessibility best-practices SEO or a page-weight summary.
GTmetrix focuses on waterfall and visual tooling. CheckFast's interactive tool returns the mobile or desktop Lighthouse performance audit you select and paid plans can monitor the aggregate Performance score. It does not automatically create a permanent dual-strategy report from each check.
Lab data (Lighthouse) is a single synthetic test and is what this interactive tool returns. Field data (CrUX) summarizes eligible Chrome traffic over a rolling window; it is not included in the interactive Endpoint result.
The tool rates each metric using its configured good/needs-improvement/poor thresholds. Treat one synthetic result as diagnostic evidence not proof of real-user experience or search-ranking impact.
Lab measurements vary with probe load network simulation target behavior and third-party scripts. Compare several runs using the same strategy before treating a small change as a regression.
Yes. Starter can schedule hourly speed checks Pro as often as every 15 minutes and Agency every 5 minutes. The current runner marks the aggregate Lighthouse Performance score as degraded below 50 and sends plan-eligible alerts after the monitor's failure policy is met.
Yes. POST Endpoint with Endpoint strategy: mobile returns a normalized JSON Lighthouse performance result. Anonymous requests are limited to 5 per hour and 10 per day; signed-in Free accounts receive 15 per hour and 50 per day.
Free tier Google PSI allows ~25 unauthenticated requests per IP per day. With your own free key from Google Cloud the limit is 25 000/day. CheckFast's hosted version uses a shared key — for high-volume use run your own deployment with your own key.
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