How to Check Favicons (the Declarations, Not the Files, and the 2015 Checklist That Misses SVG)

You scored 7/7 green and your favicon still 404s

You paste your <head> HTML into the Favicon Checker, click Analyze, and get 7/7 — all green. Then a colleague opens your site and the tab shows a blank icon because /favicon.ico returns a 404. The tool said you were fine. It wasn't wrong about what it measured; it measured the wrong thing. The "Checker" parses declarations in pasted HTML — it never fetches your site, opens the files, or validates the manifest JSON. A <link rel="icon" href="/favicon.ico"> is "ok" whether that file exists or not. The score rewards declaring favicons, not having them.

The central thing to understand: it's a declaration presence analyzer on HTML you paste, not a live site auditor. Use it to catch missing tags before deploy; confirm files load in your browser.

It parses pasted HTML, not a URL

There's no URL input. You copy your <head> from View Source and paste it. The parser runs two regexes — <link\s([^>]*)> and <meta\s([^>]*)> — over the text. A link is kept when its rel (lowercased) contains any of: icon, apple-touch-icon, manifest, shortcut, mask-icon. A meta is kept when its name (or property) is theme-color, msapplication-TileImage, or msapplication-TileColor.

Two consequences of the regex approach:

The rel match is a substring test. rel="icon", rel="shortcut icon", rel="apple-touch-icon" all match. A hypothetical rel="preiconnect" would also match — it contains "icon." Not a real risk, but the filter isn't exact.
Browsers' implicit /favicon.ico request is invisible. Browsers fetch /favicon.ico at the root even with no <link> tag. The tool can't see that fallback. A site with no link tags but a working root .ico scores low on the tool and works fine in browsers.

The seven-item checklist, and the two with loopholes

The tool scores exactly seven recommendations, always the same:

#	Check	Passes when	If absent
1	favicon.ico fallback	any icon link with `.ico` href or no sizes attr	warn
2	32×32 icon	any `sizes` includes `32x32` or any `type="image/x-icon"`	warn
3	16×16 icon	any `sizes` includes `16x16`	warn
4	Apple Touch Icon (180×180)	any `rel` includes `apple-touch-icon`	warn
5	Web App Manifest	any `rel` includes `manifest`	missing
6	Theme Color meta	any `<meta name="theme-color">`	missing

Two loopholes:

The .ico fallback passes on any unsized icon. Check 1 passes if an icon link has no sizes attribute — even <link rel="icon" href="/favicon.png"> with no sizes satisfies "favicon.ico fallback," despite being a PNG. The logic is rel includes 'icon' && (href ends .ico || !sizes). If you want the check to mean ".ico file present," use an explicit .ico href.
32×32 has a type shortcut that 16×16 doesn't. Check 2 passes on type="image/x-icon" alone — a single <link rel="icon" type="image/x-icon" href="/favicon.ico"> satisfies checks 1 and 2, with no explicit 32x32 size. Check 3 (16×16) has no equivalent shortcut — it requires sizes="16x16". So a combined .ico satisfies 32 but not 16, though both are inside the file. If you rely on a combined .ico, check 3 stays amber unless you add a redundant 16×16 link.

The Apple Touch Icon check ignores its own label

Check 4 is labeled "Apple Touch Icon (180x180)" but the code passes it on rel alone — any rel="apple-touch-icon" link, regardless of sizes. A <link rel="apple-touch-icon" sizes="57x57"> scores ok despite the 180×180 in the label. The label is aspirational; the check is rel-only. Apple recommends 180×180 (a single high-res icon it downsamples), but the tool doesn't enforce it. Verify the size yourself.

The checklist is from 2015

The seven checks cover the classic stack: .ico, 32, 16, apple-touch, manifest, theme-color. Three modern declarations are missing from the score:

No SVG favicon check. <link rel="icon" type="image/svg+xml" href="/favicon.svg"> is parsed and appears in the table, but there's no "SVG favicon" recommendation. An SVG satisfies check 1 (unsized) but gets no credit of its own.
mask-icon is parsed but never scored. The rel filter includes mask-icon (Safari's pinned-tab SVG), so it shows in the table — but no recommendation validates it.
No dark-mode theme-color. The check passes on any theme-color meta, including a media="(prefers-color-scheme: dark)" variant. But there's no check that you have both light and dark. A single light theme-color passes; the dark variant unscored.

Gotchas

The score rewards completeness, not correctness. All seven declarations pointing to 404 files scores 7/7; a single correct .ico scores 2/7. Treat the score as "did I declare the tags," not "do the favicons load."
msapplication-config isn't detected. The parser catches msapplication-TileImage and msapplication-TileColor, but not msapplication-config (the browserconfig.xml pointer). If you rely on browserconfig.xml, the tool won't reflect it.
The meta parser accepts property as an alias for name. <meta property="theme-color"> passes the theme-color check. Unusual, but allowed.
No manifest contents. With <link rel="manifest"> declared, the tool can't open the manifest to verify the 192×192 and 512×512 icons inside. The internal icons are unchecked.

Summary

The tool parses pasted <head> HTML — it doesn't fetch your site, open files, or validate the manifest. A 7/7 score means "all seven declarations present," not "all favicons load." The word "Checker" oversells a declaration presence analyzer.
Two loopholes: the .ico fallback passes on any unsized icon link (a PNG with no sizes counts), and 32×32 has a type="image/x-icon" shortcut that 16×16 lacks — a combined .ico satisfies 32 but not 16, despite both being inside the file.
The Apple Touch Icon check passes on rel alone, ignoring the 180×180 its label promises. Verify the size yourself.
The checklist predates SVG favicons: SVG is parsed but unscored, mask-icon is parsed but unscored, dark-mode theme-color variants aren't distinguished.
Generate the full set with the Favicon Generator, then check declarations here. Related checks: Meta Tag Extractor, SSL Checker, Speed Test.