Seolyzer vs WebPageTest in 2026: Crawl and log intelligence vs open-source performance diagnostics
Seolyzer watches what Googlebot does on your site. WebPageTest watches what happens to a real browser loading a single page. They rarely compete for the same job.
Seolyzer
WebPageTest- Seolyzer streams real-time server log data to show what Googlebot actually crawled. WebPageTest has no log analysis capability at all; it tests page load performance instead.
- WebPageTest's core product is free with no account required. Seolyzer requires a demo before any pricing is disclosed.
- WebPageTest runs tests through real Chrome, Firefox, or Edge browsers at 30-plus global locations. Seolyzer has no browser-based page testing feature.
- Seolyzer integrates Google Search Console directly into its cross-analysis view. WebPageTest has no GSC integration.
- WebPageTest is open source and maintained by Catchpoint, with a Pro API tier starting at $9.89/month for continuous monitoring. Seolyzer is closed-source and enterprise-priced.
- Neither tool tracks AI search visibility or AI Overviews citations. Both focus on traditional technical SEO and performance signals.
Seolyzer and WebPageTest both get filed under technical SEO, but ask them to solve the same problem and you will get two very different answers. Seolyzer is a demo-gated enterprise platform built to fuse crawl data, real-time server logs, and Google Search Console into one view of how Googlebot behaves on your site over time. WebPageTest is a free, open-source tool that runs a real browser through 30-plus global test locations and hands you a waterfall, a filmstrip, and every low-level timing metric a page load produces. One is about indexing and crawl budget; the other is about why a page is slow. The overlap is thin, but teams researching both tools usually want to know which one to add first, and the honest answer depends on whether your current problem is crawlability or speed.
The tools at a glance
Seolyzer
Technical SEO data platform combining site crawling, real-time log analysis, and Google Search Console in one interface
Seolyzer is a French cloud platform that fuses three data sources into one cross-analysis view: a site crawler, real-time server log streaming, and Google Search Console. The point is to catch discrepancies invisible in any single source, pages Googlebot crawls constantly that never show impressions in GSC, or pages your crawler flags as fine that bot activity has quietly abandoned.
The log module is what separates it from a standard crawler. You connect your server logs directly and see Googlebot activity as it streams in, rather than waiting on a weekly batch import, which matters during migrations or when diagnosing why crawl budget is being wasted. Enterprise clients like Club Med and ManoMano use it at scale, and the API lets ManoMano pull millions of internal links for their data science team.
What it does not do is test page speed. There is no filmstrip, no waterfall, no browser-based Core Web Vitals testing anywhere in the product. Pricing is also entirely demo-gated, with no public numbers and no self-serve signup.
| Feature | Starter Contact for pricing | Professional Contact for pricing | Enterprise Contact for pricing |
|---|---|---|---|
| SEO Crawler | ✓ | ✓ | ✓ |
| Log analysis | ✓ | ✓ | ✓ |
| Cross-analysis (data fusion) | ✗ | ✓ | ✓ |
| API access | ✗ | ✓ | ✓ |
| Scheduled / recurring crawls | ✗ | ✓ | ✓ |
| Google Search Console integration | ✓ | ✓ | ✓ |
| GDPR-compliant hosting | ✓ | ✓ | ✓ |
WebPageTest
The open-source gold standard for deep web performance diagnostics, trusted by engineers at Google, Mozilla, and every serious web team.
WebPageTest is the reference performance testing tool most other tools still measure themselves against. Originally built by AOL engineer Patrick Meenan and now maintained by Catchpoint, it runs tests on real browser instances across more than 30 global locations and returns a full waterfall of every request, connection timing, render-blocking resources, and layout shifts, plus a frame-by-frame filmstrip of what a user actually sees as the page loads.
The free public instance requires no account and outperforms most paid competitors on raw diagnostic depth. No-Code Experiments let you test the impact of a hypothetical change, like removing a third-party script, before touching a codebase. Every run can also include a full Lighthouse audit alongside the waterfall data.
It is a diagnostic tool, not a monitoring dashboard, and the interface assumes real performance knowledge to interpret correctly. Continuous monitoring and programmatic access require the Pro API, priced at $9.89/month, which is still inexpensive relative to what it replaces.
| Feature | Free Free | Pro API (Starter) $9.89/month |
|---|---|---|
| On-demand tests | Shared queue | Priority access |
| Global test locations | 30+ | 30+ |
| Filmstrip and video replay | Yes | Yes |
| Lighthouse integration | Yes | Yes |
| API access | No | Yes |
| Continuous monitoring | No | Yes |
Head-to-head feature comparison
| Feature | Seolyzer | WebPageTest |
|---|---|---|
| Primary focus | Crawl, log, and indexing intelligence | Page load performance diagnostics |
| Pricing transparency | Demo-gated, no public pricing | Published on-site |
| Starting price | Contact for pricing | Free |
| Site crawler | Yes | No |
| Real-time server log analysis | Yes | No |
| Google Search Console integration | Yes | No |
| Real browser performance testing | No | Yes |
| Global test locations | None | 30+ |
| Filmstrip / waterfall visual diagnostics | No | Yes |
| Core Web Vitals capture | Not mentioned | Yes (LCP, CLS, INP, TTFB) |
| Lighthouse integration | No | Yes |
| Open source | No | Yes |
| API access | Yes (paid tiers) | Yes (Pro API, $9.89/mo) |
| Continuous monitoring | Yes (scheduled crawls) | Pro API only |
Which should you choose?
SeolyzerWebPageTestSeolyzerWebPageTestWebPageTestSeolyzerThese tools are not really substitutes for each other, so a straight winner-take-all verdict would be misleading. Seolyzer answers "is Googlebot crawling and indexing my site the way I expect," using log and GSC data over time. WebPageTest answers "why is this specific page slow," using a real browser and a single test run. A technical SEO working on a large site will likely want something like Seolyzer for ongoing crawl visibility and WebPageTest for the performance diagnostics that Seolyzer does not attempt.
Bottom line
Reach for WebPageTest first if the immediate problem is page speed. It is free, requires no sales call, and gives you filmstrip-level detail within minutes of running a test. Book a Seolyzer demo if the problem is crawl budget, indexing gaps, or understanding what Googlebot is actually doing on a large or migrating site, since that is data WebPageTest simply does not collect.
Frequently asked questions
Can WebPageTest replace Seolyzer's log analysis?
WebPageTest cannot replace Seolyzer's log analysis because it tests page load performance through real browser sessions and has no capability to read server logs or track Googlebot crawl behavior over time. If crawl budget or indexing visibility is the problem, WebPageTest will not surface that data no matter how you configure a test.
Is WebPageTest really free to use?
WebPageTest's public instance at webpagetest.org is genuinely free, requiring no account and no payment. The paid Pro API, starting at $9.89 a month, adds programmatic access, priority queuing, and continuous monitoring for teams that want to automate testing rather than run one-off checks.
Why is Seolyzer pricing not listed anywhere?
Seolyzer routes every plan through a demo request instead of publishing tiers, which typically signals enterprise-level cost scaled to crawl volume and log data usage. If you need a number before a sales conversation, that is a real limitation compared to WebPageTest's fully public pricing.
Does Seolyzer test Core Web Vitals or page speed?
Seolyzer does not test Core Web Vitals or page speed; its feature set is built around crawling, server log analysis, and Google Search Console data, with nothing addressing page load performance, LCP, CLS, or INP. For Core Web Vitals diagnostics, WebPageTest or a dedicated performance tool is the right choice.
Which tool is better for diagnosing a site migration gone wrong?
Seolyzer is the stronger fit for migration diagnostics because its real-time log streaming shows exactly which URLs Googlebot is still crawling on the old structure versus the new one. WebPageTest can confirm that migrated pages still load fast, but it cannot tell you whether Googlebot has actually discovered and re-crawled them.
Do either of these tools track AI Overviews or AI search citations?
Neither Seolyzer nor WebPageTest tracks AI Overviews or AI search citations. Seolyzer's own FAQ states it has no AI search monitoring, and WebPageTest is built entirely around browser-based page load diagnostics with no AI visibility component. Both are traditional technical SEO and performance tools, not AI search tracking platforms.