Your HTML Is Only 4KB (And Why That's a Problem)
A deploy goes out. Everything is green. 200 OK responses. No backend errors. Lighthouse looks fine. But traffic drops within 48 hours. Pages stop ranking. Social previews show blank cards. You check the page source: 4.1KB. ~30 words. No H1, no content, just a root div and scripts. We see this all the time.
On This Page
What's Actually Happening
Your server is returning a shell, not a page.
A typical SPA HTML response in production looks like this:
- 3KB–6KB total size
- 1 root div
- 2–5 script tags
- No real body content
<!DOCTYPE html>
<html>
<head>
<title>My App</title>
</head>
<body>
<div id="root"></div>
<script src="/assets/index-abc123.js"></script>
</body>
</html>Everything else depends on JavaScript: fetch data, render components, inject metadata. Here's the failure mode:
Quick verification (30 seconds):
curl -s https://yourdomain.com | wc -c
# If under ~10,000 bytes, your page is likely empty
curl -s https://yourdomain.com | grep -oP '\w+' | wc -l
# If under ~100 words, your content doesn't exist to crawlersWant the automated version? Run the DataJelly Visibility Test — it does this comparison for you.
What Most Guides Get Wrong
The industry advice is flat wrong here. You'll hear:
"Google renders JavaScript"
Sometimes. For some pages. With an unpredictable delay. Deep routes often never get rendered.
"Just use React, it's fine"
React ships a root div. Without SSR or prerendering, that root div is your entire HTML payload.
What actually happens in production with Googlebot's rendering queue:
| Route | Rendered? | Indexed? |
|---|---|---|
| / | Sometimes | Usually |
| /pricing | Partially | Inconsistent |
| /blog/post-123 | Rarely | No |
And other bots don't even try:
- AI crawlers (GPTBot, ClaudeBot, PerplexityBot): read raw HTML only
- Social bots (Slack, Twitter, LinkedIn): no JS execution
- SEO tools (Ahrefs, Screaming Frog defaults): no JS execution
If your content is not in the initial HTML, it is invisible. This is the same problem we cover in depth in Why Google Can't See Your SPA and Why ChatGPT Can't See Your Content.
What We See in Production
These are not edge cases. This is normal. We see these patterns across hundreds of sites every week.
Empty HTML, indexed anyway
HTML: 4.3KB | Words: 25 | Title: correct
Page content: missing
Result: page ranks for nothingGoogle indexed the title tag but found no body content. The page exists in the index but has zero ranking signals.
Hydration blocked by API failure
JS loads → API call returns 500 → page never renders
HTML still returns 200 with empty body
Users see spinner, bots see nothingThis is a silent failure. Your monitoring says "200 OK" but the page has no content. We wrote about this pattern in Your Site Returns 200 OK — But Is Completely Broken.
Deep routes completely empty
/ → works (sometimes rendered)
/features → works (partially rendered)
/blog/post → 4KB shell (never rendered)Bots hit deep URLs directly. They never navigate from your homepage. If the route returns a shell, they see nothing. Check yours with the Page Validator.
Metadata injected too late
OG tags added via JavaScript → HTML has none
→ Slack preview: blank
→ Twitter card: missing image
→ LinkedIn: wrong titleSocial bots never execute JS. If your OG tags aren't in the raw HTML response, every share link is broken. See Fixing Broken Social Previews in SPAs.
Quick Test: Is Your Site Affected?
Don't guess. Measure it. Use this step-by-step diagnostic to check what bots actually see on your site right now.
Quick Test: What Do Bots Actually See?
Most people guess. Don't.
Run this test and look at the actual response your site returns to bots.
Fetch your page as Googlebot
Use your terminal:
curl -A "Googlebot" https://yourdomain.comLook for:
- Real visible text (not just
<div id="root">) - Meaningful content in the HTML
- Page size (should not be tiny)
Compare bot vs browser
Now test what a real browser gets:
curl -A "Mozilla/5.0" https://yourdomain.comIf these responses are different, Google is indexing a different page than your users see.
Stop guessing — measure it.
Real example: 253 words vs 13,547
We see this constantly. Here's a real example from production: Googlebot saw 253 words and 2 KB of HTML. A browser saw 13,547 words and 77.5 KB. Same URL — completely different content.
If your HTML doesn't contain the content, Google doesn't either.
Compare Googlebot vs browser on your site → HTTP Debug ToolCheck for common failure signals
We see this all the time in production:
- HTML under ~1KB → usually empty shell
- Visible text under ~200 characters → thin or missing content
- Missing <title> or <h1> → weak or broken page
- Large difference between bot vs browser HTML → rendering issue
Use the DataJelly Visibility Test (Recommended)
You can run this without touching curl. It shows you:
- Raw HTML returned to bots (Googlebot, Bing, GPTBot, etc.)
- Fully rendered browser version
- Side-by-side differences in word count, HTML size, links, and content
What this test tells you (no guessing)
After running this, you'll know:
- Whether your HTML is actually indexable
- Whether bots are seeing partial content
- Whether rendering is breaking in production
This is the difference between "I think SEO is set up" and "I know what Google is indexing."
If you don't understand why this happens, read: Why Google Can't See Your SPA
If this test fails
You have three real options:
SSR
Works if you can keep it stable in production
Prerendering
Breaks with dynamic content and scale
Edge Rendering
Reflects real production output without app changes
If you do nothing, you will not rank consistently. Learn how Edge Rendering works →
This issue doesn't show up in Lighthouse. It shows up in rankings.
Solutions Compared
There are three real approaches to fixing this. Here's what actually works and what breaks.
| Approach | How it works | Breaks when |
|---|---|---|
| Prerendering | Static HTML snapshots at build time | Dynamic routes, frequent content changes, scale >100 pages |
| SSR | HTML rendered on every request | Slow TTFB, complex infra, hard to scale under load |
| Edge Snapshots | Pre-rendered HTML served only to bots at the edge | Doesn't break — bots always get full HTML, users get normal SPA |
Why edge snapshots work
- • Bot → gets full HTML snapshot (30KB–80KB)
- • User → gets normal SPA experience
- • No app rewrite required
- • No runtime rendering cost
This is the only approach we see consistently work without breaking the app. Learn how Edge works →
Practical Checklist
Run these checks right now. If any fail, your page is not indexable.
curl your page
HTML <10KB? Problem.
View page source
Just a root div and scripts? No real paragraphs? Problem.
Count words in raw HTML
<200 words = effectively empty.
Disable JavaScript and reload
Blank page = broken for bots.
Hit deep URLs directly (not just homepage)
Individual routes return empty shells? Problem.
Check OG tags in raw HTML
Missing = social previews will fail.
Fix criteria — all must pass:
- HTML contains real content on first response
- H1 + body text present in raw HTML
- Internal links exist without JS
- Metadata (title, OG tags) present without JS
If your HTML is 4KB, your site is not SEO-compatible.
Not "suboptimal." Not "needs improvement." Broken. You are shipping empty documents and hoping a crawler reconstructs them. Sometimes it works. Most of the time it doesn't.
What DataJelly Does About This
Instead of sending a 4KB shell, DataJelly Edge serves full HTML snapshots (30KB–100KB) to bots. Content is present immediately. No JS dependency. For AI crawlers, clean Markdown is served — no parsing or rendering required.
Works with React, Vite, Lovable SPAs. No framework rewrite required. The fix is at the edge, not in your app.