The short version
- The Ahrefs audit is metered in crawl credits — 100,000 on Lite, 500,000 on Standard, 1,500,000 on Advanced.
- Screaming Frog runs locally with no metering at all, bounded only by your machine’s memory.
- Ahrefs Webmaster Tools gives you a free site audit for domains you verify, which is a genuinely good starting point.
- For investigation and custom extraction, a desktop crawler may fit your work alongside the suite you pay for.
Ahrefs bundles a competent cloud site audit into every plan, and for a lot of sites it is entirely sufficient. The two things worth understanding before relying on it are how the credit system constrains you and where configurability runs out.
There is also a free option here that gets overlooked: Ahrefs Webmaster Tools includes site auditing for domains you verify, at no cost. For a small site owner that is a genuinely useful free tool sitting alongside the Screaming Frog free tier.
The short answer
Fit for your workflow
Ahrefs for scheduled monitoring, Screaming Frog for anything you need to investigate.
Use the Ahrefs audit to keep an eye on things on a schedule without configuring anything. Reach for Screaming Frog when you need custom extraction, a specific crawl configuration, or an unmetered crawl you can iterate on. The two cost structures reflect the two use cases: metered convenience versus unmetered control.
- Already pay for Ahrefs, small site
- The bundled audit is fine. Add the free Frog tier for depth.
- Large site
- Watch your credits, and get a Frog licence for investigation.
- No budget at all
- Ahrefs Webmaster Tools free plus Screaming Frog free tier.
- Technical SEO consultant
- Screaming Frog licence regardless of which suite you use.
Crawl credits, explained
Ahrefs crawl credits are consumed by site audits. Screaming Frog has no metering — the licence is per user per year and the only limit is your own machine.
For a site of a few thousand URLs audited monthly, the Lite allowance of 100,000 credits is comfortable. For a large ecommerce catalogue, or for anyone re-crawling frequently while fixing something, credits become a real constraint and change your behaviour — you start rationing crawls, which is exactly when you most want to run them.
That behavioural effect is the strongest practical argument for a local crawler. When crawling is free at the margin, you crawl after every change and catch regressions immediately. When each crawl costs credits, you crawl monthly and find out about a template regression four weeks late.
Configurability, compared
Crawling behind authentication is the row that catches people out. If you need to audit a staging environment or a members-only area, the cloud audit generally cannot reach it and the desktop crawler can.
Auditing before launch
The strongest practical argument for a desktop crawler is timing. A cloud audit can only see what is already public, which means it finds your migration mistakes after they have shipped. A local crawler can audit staging behind HTTP authentication, which is where redirect maps, canonical logic and missing metadata should actually be caught.
That matters most during exactly the events where SEO damage is largest and hardest to reverse — replatforms, URL restructures and domain changes. Crawl staging, fix what you find, launch, then crawl the old URL list to confirm every redirect resolves in one hop. See 301 vs 302 for the redirect mistakes worth checking for.