SYNTHLUCIDA SEOCHECKER Free SEO check for your website
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SYNTHLUCIDA

SEOCHECKER

Find out how search engines see your page.

Upload any HTML page — an export from WEBZENith or PAGEZEN, or any other HTML file — and get an overview of core SEO signals in seconds. Free, no sign-up, nothing is uploaded anywhere: everything runs right in your browser.

Tip: if you select several files at once (a full export from WEBZENith or PAGEZEN), SEOCHECKER will also check the internal links between pages.

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Summary

How SEOCHECKER works

SEOCHECKER is a free, browser-only SEO tool: your file never leaves your device, nothing is uploaded to a server, and the only thing that gets stored is a local check history you control. Here's how to get the most out of it.

  • 1

    Choose your file(s)

    Click “Choose HTML file(s)” and pick any exported page — from WEBZENith, PAGEZEN, or any other site. Select several at once to also check the internal links between them.

  • 2

    Run the check

    Press “Check”. SEOCHECKER parses the page and scores it against 19 signals across five categories — instantly, right in your browser.

  • 3

    Read your score

    The gauge shows your overall score out of 100, with a plain-language verdict and a “What to focus on first” list of the most important fixes.

  • 4

    Fix common issues on the spot

    For problems SEOCHECKER can help with — title, meta description, headings, missing image descriptions — use the Quick fix panel to correct them directly, then download the fixed HTML file.

  • 5

    Export or save your results

    Use “Export as PDF” to keep a record or share it with a client, or revisit any past result anytime from Check history — saved locally in your browser only.

  • 6

    Install it as an app

    On supported devices, use the banner at the top of the page to install SEOCHECKER to your home screen for quick, offline-ready access.

SEO articles

A short overview of what SEOCHECKER actually checks, and why it matters.

What SEO is and why it matters

SEO (search engine optimization) is a set of steps that make a website easier for Google and other search engines to understand, so they can rank it properly and show it to people searching for what you offer. It's not a trick or a one-off fix — it's more like ongoing care for a site's technical foundations, content and structure.

A website with good SEO usually loads quickly, works well on mobile, has clearly named pages, and content that genuinely matches what people are searching for. A site without SEO basics, on the other hand, might be beautiful and useful, but search engines may not even know it exists.

Summary

SEO doesn't decide how a website looks — it decides whether anyone finds it at all.

Title tag: the most important line the user sees

The title tag is the page's name, shown as the clickable headline in search results and as the browser tab's title. It's the first thing a person notices in the results, and search engines also treat it as a strong signal of what the page is about.

The ideal length is roughly 30–65 characters — a shorter title wastes the available space, a longer one gets cut off in the results. A good title includes the page's main topic and is unique for every page on the site.

Summary

Every page should have its own, clear title — it's the business card seen by both people and algorithms.

Meta description: the text that decides the click

The meta description is a short piece of text below the title tag in search results. Google increasingly replaces it with its own excerpt from the page, but if you write a good description that matches the content, there's a better chance it gets shown — and, more importantly, read and clicked.

The ideal length is 70–160 characters. It works best when it clearly summarizes the page's value, rather than reading like a list of keywords.

Summary

The meta description doesn't directly affect ranking position, but it significantly affects how many people click through.

Heading structure H1–H6: why the order matters

Headings H1 through H6 create a hierarchy on the page, much like an outline in a document. There should be only one H1, summarizing the page's main topic, while the other headings (H2, H3…) split the content into logical sections.

Search engines and screen readers both rely on the heading structure to understand what's the main topic and what are subtopics. A page with no headings, or a chaotic structure, is harder for both to read.

Summary

Well-structured headings help search engines understand the content faster, and help people find their way around the page more easily.

Mobile display: why the viewport tag can't be missing

Most website visits today come from mobile devices, and Google has long evaluated primarily the mobile version of a page (so-called mobile-first indexing). The viewport meta tag tells the browser how to render the page on a small screen — without it, the display can shrink down to the point of being unreadable.

Besides the viewport, it's also worth checking the font size, the spacing of buttons for fingers, and whether content overflows off the screen.

Summary

If a page doesn't work well on mobile, it will feel the impact in search results regardless of how good the content is.

HTTPS: security that's also an SEO signal

HTTPS encrypts the communication between browser and server, so no one along the way can eavesdrop on or alter the data. Besides security, it's also one of the signals Google takes into account when ranking a site, and browsers actively flag sites without HTTPS as "not secure".

Practically every hosting provider offers HTTPS for free today (for example via Let's Encrypt), so there's no reason not to have it.

Summary

HTTPS is a standard today, not a bonus — its absence raises distrust with both people and search engines.

Image alt text: accessibility and SEO in one

The alt attribute describes an image's content in text — it's used by screen readers for visually impaired users, it shows up when the image fails to load, and search engines read it too, since they can't see the image content itself.

A good alt text is brief and descriptive, not stuffed with keywords. Purely decorative images can have an empty but present alt="" attribute, which tells screen readers to skip the image.

Summary

Alt text isn't just an SEO detail — it's real help for people who can't see the image.

Open Graph: how your link will look on social media

Open Graph tags (og:title, og:description, og:image) determine what the page preview looks like when shared on Facebook, LinkedIn, or elsewhere. Without them, the platform has to guess at a preview itself, which often means a random image gets picked, or the card doesn't show up at all.

A filled-in, visually clear preview increases the chance that people will notice it in their feed and click through.

Summary

Open Graph doesn't affect your ranking in search results, but it directly affects how well your content spreads on social media.

Structured data: how to get rich results

Structured data is code (most often in JSON-LD format) that tells search engines exactly what a page contains — a star-rated review, a recipe, questions and answers, business information, and so on.

Thanks to this, an enhanced, more visually rich result (a so-called rich snippet) can appear in the results, drawing more attention than a plain blue link. It's not a guarantee of a better position, but it does increase visibility.

Summary

Structured data helps search engines understand a page's content precisely, rather than just guessing from the text.

robots.txt and sitemap.xml: how search engines find you

The robots.txt file tells search engines which parts of a site they may crawl and which they may not. Sitemap.xml, on the other hand, works as a map of the site — a list of all the important addresses you want search engines to know about and index.

Both files are usually placed in the domain's root, and robots.txt can even link directly to the sitemap. Without them, search engines will still find the site, but more slowly and with more difficulty.

Summary

They're not mandatory, but they make it much easier for search engines to find their way around your site.

Internal linking: why links within your site help

Internal links are links leading from one page on your site to another page on the same site. They help people find related content, while also showing search engines which pages are important and how they relate to each other.

A page that no link on the site points to is harder to discover and gets less trust. A basic rule: whenever you mention a topic you've covered in detail elsewhere, link to it.

Summary

The more thoughtfully a site's pages are linked together, the easier it is for both people and search engines to navigate them.

How long does it take for SEO changes to show results?

SEO isn't instant. Smaller technical fixes (title, meta description, alt text) can show up in results within days to a few weeks, once a search engine crawls and re-evaluates the page.

Bigger changes — new content, building the site's credibility, restructuring — often take weeks to months to show. How often search engines visit the site also affects the speed.

Summary

SEO is a long game — the first results come gradually, not overnight.