Comparisons
Screaming Frog vs Online SEO Auditors: Which to Use When
A desktop crawler maps a whole site. An online auditor inspects one URL from outside. Choosing between them is really choosing which question you are asking.
Run a fresh DomainLens audit and use the report as your priority list.
They answer different questions
The distinction is scope, not quality. A crawler tells you that 340 pages share a canonical problem. An auditor tells you what one page returns right now, from outside your network, without configuring anything.
| Desktop crawler | Online auditor | |
|---|---|---|
| Scope | Every URL it can reach | One URL at a time |
| Runs from | Your machine and IP | A server elsewhere |
| Setup | Install, configure, wait | Paste a URL |
| Site-wide patterns | Its whole purpose | Not possible |
| Sharing results | Export a file | Send a link |
| Repeatability | Manual re-runs | Trivially repeatable |
| Cost at scale | Licence, plus your time | Usually free per check |
What a desktop crawler does that nothing else can
Every one of those needs the whole graph. No single-URL tool can compute them, and no amount of checking pages individually adds up to the same answer.
- Finds orphan pages by comparing the crawl against a sitemap — only possible with the full graph.
- Surfaces redirect chains across the whole site rather than on one URL.
- Maps internal link distribution, so you can see which pages are starved of links.
- Detects duplicate title and description clusters at scale.
- Crawls staging environments behind authentication.
What an online auditor does better
It checks from outside. A desktop crawl runs from your IP, on your network, possibly through your VPN and your DNS — which is exactly the configuration least likely to reproduce what a visitor or Googlebot sees. A firewall rule blocking a datacentre range is invisible from your desk.
It is also immediate and shareable. Confirming that a fix deployed correctly is a paste-and-click, not a crawl configuration, and the result is a link a colleague can open rather than a file they have to be sent.
- Verifying a single fix after deploy, without re-crawling.
- Checking a competitor or a client site you have no access to.
- Reproducing what an outside client sees, from an outside network.
- Handing a non-technical colleague something they can run themselves.
Where each one misleads you
The most expensive of these is the first. A crawl from an IP your firewall trusts will happily report a healthy site that Googlebot cannot reach at all.
| Trap | Tool | Why it happens |
|---|---|---|
| Crawl looks clean, site is broken | Desktop | Ran from a whitelisted IP or with JS off |
| Crawl finds thousands of "errors" | Desktop | Default settings crawl parameters and filters |
| Page passes, site still fails | Online | One URL says nothing about the other 5,000 |
| Different results each run | Either | Caching, CDN nodes, or A/B tests |
| Rendering differences | Either | JS rendering off by default in many crawlers |
A workflow that uses both
The pairing is the point: the crawler finds the pattern, the external check confirms reality. For choosing between Google's own data and third-party tools see Search Console vs third-party tools , and for the free-versus-paid question see free vs paid SEO audit tools .
- 1Crawl the site to find patterns — which templates, how many URLs, what repeats.
- 2Pick one representative URL per pattern and check it from outside to confirm the crawler is not seeing a privileged view.
- 3Fix at the template level, since the crawl told you the fault is systemic.
- 4Verify the fix on that representative URL with an online check, immediately.
- 5Re-crawl only once several fixes have shipped — crawling after every change wastes hours.
How DomainLens contributes
DomainLens is the online half: it checks any URL from outside your network and reports status codes, indexability, canonical, structured data and Core Web Vitals in one pass, with a shareable result. It does not crawl a whole site, which is precisely why it complements a desktop crawler rather than replacing one. See manual vs automated audits for how the collected evidence becomes a decision.
- Is Screaming Frog free?
- There is a free tier limited to 500 URLs per crawl, with several features reserved for the paid licence. That ceiling is enough for a small site and restrictive for anything larger.
- Can an online auditor replace a crawler?
- No. Site-wide questions — orphan pages, internal link distribution, duplicate clusters — need the full graph, which a single-URL tool never has.
- Why does my crawl show no problems when the site is failing?
- Most often the crawl ran from an IP your firewall trusts, or with JavaScript rendering disabled. Verify from outside before concluding the site is healthy.
- Should I enable JavaScript rendering when crawling?
- For any site that renders content client-side, yes — otherwise the crawler reports an empty shell. It is substantially slower, so use it on a sample rather than every crawl.