Framework-Aware SEO Crawler for Next.js, React & TanStack
Generic SEO tools only look at basic HTML tags. Sohnics SEO Crawler runs a dual-pass audit (Raw HTTP vs Rendered Playwright DOM) to detect hydration mismatches, invisible client-injected OpenGraph cards, and indexation blockers.
The Dual-Pass Revolution
Modern JavaScript frameworks don't just output static HTML. Different crawlers see entirely different states of your website.
Pass 1: Raw HTTP Crawler
Social sharing bots (Facebook, X, LinkedIn, WhatsApp) and initial search indexers never execute JavaScript. They consume raw server HTML.
// What Twitterbot sees:
<title>My Next.js App</title>
<!-- Missing og:image (injected client-side) -->
<div id="root"></div>
Result: Blank social preview cards and degraded SEO indexation.
Pass 2: Headless Browser DOM
Playwright loads your page in real Chromium, listens to browser console errors, waits for hydration, and captures DOM mutations.
// What Playwright catches:
Console: Hydration mismatch at <p><div>
Client added: <meta property="og:image" ...>
Screenshot & 404 failed network request recorded
Result: Complete visibility into hydration mismatches & DOM drift.
Built Specifically for the Modern Web
Every audit detector runs against pure TypeScript logic returning actionable explanations and copy-paste code fixes.
Hydration Mismatch Engine
Detects invalid HTML nesting (<p><div>), non-deterministic renders (Date.now(), Math.random()), and browser extension attribute pollution before it hurts user experience.
Dynamic OpenGraph Previews
Flags any OG or Twitter tag rendered via client-side JavaScript. Renders live social preview cards from RAW HTML so you see what Facebook, X, and LinkedIn actually see.
Indexation Blocker Shield
Audits robots.txt rules per user agent, client-injected noindex tags, canonical discrepancies between server and client, redirect loops, and soft 404s.
Framework Intelligence
Accurately identifies Next.js App Router (RSC payloads) vs Pages Router, Vite SPAs, and TanStack Start/Router, giving you framework-tailored recommendations.
Console Error Listener
Captures browser runtime exceptions, hydration error codes (#418, #425), and failed asset network requests during page load.
100% Free Forever
No subscription tiers, no restricted reports, no credit card required. High-performance public tool hosted by Sohnics engineering.
Frequently Asked Questions
Is Sohnics SEO Crawler completely free?
Yes, 100% free with no paid tiers, no trials, and no credit cards. We provide fair-use limits (up to 50 pages per scan for anonymous users) to protect the service from abuse and keep it free for all developers.
How does it detect React hydration errors?
We load your site in a headless Chromium browser instance with Playwright. We capture all console messages and match against React 18 & 19 hydration signatures, while also comparing the server-rendered HTML tree against the hydrated client DOM.
What is SohnicsSEOBot?
SohnicsSEOBot/1.0 is our polite web crawler user-agent. It strictly respects your robots.txt directives, limits concurrency to 2 requests per host, and includes an automatic opt-out mechanism at /bot.
Can I embed my site's SEO score badge?
Yes! Every crawl report includes an embeddable dynamic SVG badge URL that you can place in your README, docs, or site footer.