What font is this? And is it big enough to read?
Font Detector tells you which font a website really renders, then colours every line of small text on a size heat map and checks contrast, spacing and font loading. Free, with no account.
- No account, no limits
- Runs only when you click it
- Nothing about the page is sent to us
Comfortable, 16px and up
Good type is invisible: readers notice the words, not the letters. This line is set at 16px.
Slightly small, 14 to under 16px
Good type is invisible: readers notice the words, not the letters. This line is set at 15px.
Small, 12 to under 14px
Good type is invisible: readers notice the words, not the letters. This line is set at 13px.
Too small, under 12px
Good type is invisible: readers notice the words, not the letters. This line is set at 10px.
What it does
Six tabs, one click away.
Click the icon on any page and a panel opens beside it. Nothing is installed on the page and nothing is changed.
Inspect
Hover any text and click to pin it. See the font that is really rendering, the full declared stack, size in px, rem and pt, weight, line height, spacing and contrast. Copy the CSS in one click.
Fonts
Every font on the page, ranked by how much text it sets, with its source, files, format, file size and font-display. Click a font to highlight everywhere it is used.
Sizes
The heat map, the share of text at each size, a legibility score, and a list of the text that is too small, with a button that scrolls straight to it.
Audit
A checklist across readability, accessibility, performance and consistency. Every item says whether it is a WCAG standard or a common convention.
Report
Copy a summary, download Markdown, CSV or JSON, copy CSS variables or a Tailwind theme, or open a printable report.
Settings
Your own size limits, gentler rules for captions and buttons, highlight style, light or dark panel, left or right side.
Who it is for
Built for everyone who touches a page.
Designers
Identify a font in seconds, check how a build matches the design, and pull the page's type scale out as tokens.
Content people
See at a glance which parts of a page are too small or too faint to read comfortably on a phone.
SEO people
Check mobile readability and web font loading, two things that shape how a page feels to the visitors you worked to bring in.
Accessibility auditors
Contrast for every text style, line height, line length, zoom blocking and viewport-only sizes, each tied to its WCAG criterion.
The honest answer
Is 16px required for SEO? No.
Google has no font size ranking rule. Lighthouse used to flag pages where a large share of the text was under 12px, never 16px, and it dropped even that check in version 13 in 2025. WCAG, the accessibility standard, does not set a minimum size either.
So why does Font Detector start its yellow band at 16px? Because 16px is the browser default and the minimum many design systems use for body text. Smaller text is harder to read on a phone, and people leave pages they struggle to read. Size is about your readers, not about a ranking signal.
That is why every check in the Audit tab says whether it is a WCAG standard or a common convention, and why every limit is yours to change.
Privacy
It reads the page. It tells no one.
- Runs only on the tab where you click it, and only after you click it. No access to other sites.
- Everything is worked out inside your browser. Nothing about the page is sent to us or anyone else.
- No account, no analytics, no ads, no tracking.
- Details are in our privacy policy.
How to use it
Three steps.
- 1
Add it to Chrome
Install Font Detector from the Chrome Web Store and pin its icon from the puzzle piece menu.
- 2
Open any page
Go to the website you want to check and click the icon, or press Alt+Shift+D.
- 3
Read the results
Hover and click text to identify its font, and use the Sizes, Audit and Report tabs to see the whole page.
Questions
Font Detector FAQ.
How do I find out what font a website uses?
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Install Font Detector, open the website, and click the extension's icon or press Alt+Shift+D. Point at any text and click it. The panel shows the font that is actually drawing that text, not just the list of fonts the stylesheet asks for, along with its size, weight, spacing and colour.
Is 16px the minimum font size for SEO?
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No. Google has no font size ranking rule. Lighthouse once flagged pages where much of the text was under 12px, and removed even that check in version 13 in 2025. WCAG sets no minimum size either. 16px is the browser default and a widely used minimum for body text because it is comfortable to read, especially on phones. Font Detector uses it as a readability limit, which you can change.
What do the red, orange and yellow highlights mean?
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Red is text under 12px, orange is 12 to under 14px, and yellow is 14 to under 16px. Captions, labels, buttons and footers are small on purpose, so they are judged two pixels more gently. You can change all three limits, or switch to a stricter 14, 16 and 18px preset.
Does it work on any website?
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It works on ordinary web pages, including text inside shadow DOM and frames from the same site. Chrome does not let any extension read its own pages, the Chrome Web Store, PDF files, or frames that come from a different site, so those are skipped and the panel tells you so.
Is it really free?
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Yes. Every feature is free, with no account, no trial and no limits. It is made by Content Anchor, which also makes free font tools and Font Studio, and the panel links to those tools.
Does Font Detector collect my browsing data?
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No. It only runs on a page after you click its icon, press its shortcut or choose its menu item. It reads that page inside your browser and sends nothing about it to us or anyone else. It has no analytics and no ads.
Can it tell me whether a font is licensed?
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It can read what the font file says about itself: designer, foundry, licence text and licence link. That is useful for finding out where a font comes from, but it does not prove that a particular website holds a licence to use it.
What does the contrast check use?
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WCAG 2.2 success criterion 1.4.3: a ratio of at least 4.5 to 1, or 3 to 1 for large text (24px, or 18.66px when bold). Text on images, gradients or filtered backgrounds has no single background colour, so Font Detector marks it for a check by eye instead of guessing.
Can I share the results?
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Yes. The Report tab copies a short summary, downloads the full audit as Markdown, CSV or JSON, copies the page's fonts and sizes as CSS variables or a Tailwind theme, and opens a printable report you can save as a PDF.
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