---
title: "How do SEO audits work"
category: audits
slug: how-do-seo-audits-work
canonical_url: https://lemaudit.com/help/audits/how-do-seo-audits-work
last_reviewed: 2026-05-04
source: LemAudit Help Center
---
# How do SEO audits work?

An audit fetches the target site's HTML once, runs a free Google PageSpeed check on it, and scores 5 categories: SEO, performance, security, mobile, accessibility. The full run takes 12–25 seconds and produces 1 health score from 0 to 100.

## What an audit actually checks

Each audit looks at the homepage by default. On Growth and Agency plans it also fetches the top 5 or 10 internal pages. LemAudit reads the rendered HTML, the response headers, and the free PageSpeed report. There is no crawler that hammers the whole site, no third-party DA/DR API, and no paid metric. Every signal comes from the page itself or from Google's free APIs.

Think of it like a 20-point pre-purchase car inspection. Quick, cheap, and good enough to spot the deal-breakers.

## How LemAudit runs it

The pipeline lives in the run-audit edge function. It opens the URL with a strict 10-second HTML timeout and 25-second PageSpeed timeout (so 1 slow site cannot stall the queue). Each check writes a row into the audits table, then the [scoring engine](/help/audits/how-is-the-health-score-calculated) collapses them into the headline score. The full [issue list](/help/audits/what-types-of-issues-does-the-audit-find) shows which checks failed at which severity.

## Worked example

A regional bakery's homepage runs through the audit at 2:14pm. HTML fetch takes 1.8s, PageSpeed takes 9.2s, scoring takes 0.4s. Final score: 54. The 3 critical findings are no HTTPS redirect, missing meta description, and an LCP of 6.1s. That report becomes the lead's first sales asset.

## When this isn't right

Sites behind login walls, paywalls, or aggressive bot protection (Cloudflare challenge pages, hCaptcha) cannot be audited because LemAudit never sees the real HTML. For those, [re-audit](/help/audits/can-i-re-audit-a-lead-s-website) after the prospect lifts the block. Or run the audit manually from a logged-in browser session and paste the URL of a public page.

*Category: SEO Audits*

## Related
- [How is the health score calculated](https://lemaudit.com/help/audits/how-is-the-health-score-calculated)
- [What types of issues does the audit find](https://lemaudit.com/help/audits/what-types-of-issues-does-the-audit-find)
- [How do I identify the best leads](https://lemaudit.com/help/leads/how-do-i-identify-the-best-leads)

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For the interactive version visit https://lemaudit.com/help/audits/how-do-seo-audits-work