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URL Safety Analyzer

Check a link for typosquats, brand-in-subdomain tricks, mixed-alphabet homographs, and hidden destinations. Public Suffix List parsing, explainable per-rule scoring, and the link is never fetched.

Runs locally in your browserMore web toolsJump to full guide

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URL Safety Analyzer: a worked example

A "your account is locked" email links to the URL below and you want a sober breakdown before anyone in the team clicks it.

URL pasted

http://paypa1-secure-login.account-verify.ru/login?next=update
What URL Safety Analyzer produces

Risk findings

Owner (registered domain): account-verify.ru

+70 [identity]   "paypal" is in the subdomain, not the actual domain
+30 [content]    Hostname reads like a prompt to act: secure, login, verify, account
+12 [connection] The connection is not encrypted

Risk score 100 of 100: strong signs of a malicious link

The Public Suffix List separates the real owner, account-verify.ru, from the reassuring text in front of it, and "paypa1" is matched to the brand because comparison happens on the shape the eye sees rather than on the exact characters. Words like secure and verify count here because they are in the hostname, where a real service has no reason to put them; the same words in a path would score nothing. Each finding shows its own contribution, so the verdict can be checked rather than trusted. The link is never fetched, which is why this is structural evidence rather than a threat-intelligence verdict.

About the URL Safety Analyzer

Before you click a suspicious link, paste it here. The analyzer works out who really owns the address using the Public Suffix List, then checks it for typosquats, brand names hidden in subdomains, mixed-alphabet homographs, destinations concealed behind an @ sign, and the structural patterns phishing campaigns share. Every finding shows what it contributed to the score. The link is never fetched.

Key features

  • Public Suffix List parsing, so co.uk is a suffix and paypal.com.evil.tk is not PayPal
  • Typosquat detection by visual skeleton and Damerau edit distance, catching digit swaps, rn-for-m, i-for-l, and transpositions
  • Brand names in subdomains identified as belonging to the domain that actually owns them
  • Official brand domains recognised as positive evidence, so login pages on them are not flagged
  • Punycode decoded, with only genuinely mixed-alphabet labels treated as homograph attacks
  • Credentials hidden before an @ sign unmasked, showing the real destination
  • Hostname signals weighted heavily and path signals lightly, so /login on a real site is not a warning
  • Free-registration suffixes weighted on cost, not on country
  • Opaque shorteners separated from brand-operated redirectors
  • Per-finding point contributions, grouped by category, so the score can be audited
  • Local history, a copyable JSON report, and shareable permalinks
  • String-only analysis: the link is never fetched and nothing you paste leaves the page

How to use

  1. 1Paste the link into the input, or pick one of the worked examples.
  2. 2Read the owner line first: that registered domain is where the link actually goes.
  3. 3Work through the findings, grouped by identity, connection, structure, and content, each showing its own contribution to the score.
  4. 4Copy the JSON report or a permalink if you need to pass the result to someone else.

How it works

The analysis starts by working out who actually owns the address, because almost every phishing trick is an attack on that one question. The hostname is parsed against the Public Suffix List, which separates the registered domain from the subdomains in front of it and from the suffix behind it. That distinction is the whole game: in paypal.com.secure-login.tk the owner is secure-login.tk and "paypal.com" is just text someone put in front of it, while in www.bbc.co.uk the owner is bbc.co.uk and co.uk is a two-part suffix, not a subdomain. The result panel names the registered domain explicitly, so the answer to "where does this actually go" is the first thing you read.

Brand impersonation is then checked in three distinct ways, because the three attacks look different. A domain whose name imitates a brand is caught by folding the label down to the shape the eye sees: digits that stand in for letters, sequences like rn that read as m, and the i, l and 1 family that are indistinguishable in most sans-serif fonts. On top of that a Damerau edit distance catches single insertions, deletions, substitutions and transpositions, which is why dropbxo.com is recognised as dropbox rather than dismissed as merely similar. A brand name sitting in the subdomain of a domain someone else owns is reported as exactly that. And a brand name combined with words like secure, support or billing inside the registered domain is treated as the lure it usually is. Crucially, the check runs the other way too: when the registered domain is one the brand genuinely uses, that counts as positive evidence and login or account pages on it are expected rather than suspicious. An earlier version of this tool rated paypal.com itself as Caution; it now rates it clean and rates paypa1.com as dangerous.

Internationalised domains are handled by decoding them rather than by suspecting them. Any xn-- label is decoded back to the characters it represents, and the analysis then looks at what those characters are. A name written consistently in one writing system is normal and scores nothing; münchen.de is a German word, not an attack. A single label that mixes alphabets, Latin letters with a Cyrillic or Greek lookalike dropped in the middle, is the actual homograph attack and is flagged heavily. The decoded form is shown alongside the raw one so you can see what your browser will display.

The remaining signals are weighted by where they appear. Words like login, verify and secure carry real weight in a hostname, where a legitimate service has no reason to put them, and none at all in a path, where /login is simply where a real site puts its login page. Suffixes are judged on registration economics rather than geography: a penalty applies to suffixes that are free or near-free and therefore attract disposable campaign domains, and no penalty at all applies to a country suffix for being foreign. Shorteners are split in two, because bit.ly genuinely hides its destination while youtu.be is operated by the site it points at. The rest covers credentials embedded before an @ sign, bare IP addresses used as hosts, javascript: and data: schemes, non-standard ports, executables disguised with a double extension, deep subdomain chains, and generated-looking names.

Every finding shows what it contributed to the score, grouped by whether it concerns identity, the connection, the structure of the address, or what it points at, so the verdict is auditable rather than a number to take on faith. The weights were calibrated against a corpus of 42 real well-known URLs and 45 synthetic attack patterns, and the current engine rates none of the real ones as risky while flagging all 45 of the attacks. The whole thing runs on the text of the address in your browser: nothing is fetched, no lookup is made, no reputation service is consulted, and nothing you paste leaves the page. That is a deliberate limit as much as a privacy promise, and the tool says so: a clean result means no warning signs in the address, not that the destination is trustworthy, and a brand-new phishing domain that copies nothing and misspells nothing will look exactly like an ordinary site.

Practical scenarios

  • Email link vetting

    Check links claiming to be from a bank, a courier, or an IT department. The owner line answers the only question that matters in seconds.

  • Slack and chat link checking

    Verify unfamiliar URLs shared in a channel, and see immediately whether a shortener means the destination is unknowable.

  • Security awareness training

    Show how the same brand name means completely different things in a domain, a subdomain, and a path. The worked examples demonstrate a typosquat, a subdomain trick, a homograph, and an @ sign attack side by side.

  • Triaging a reported phish

    Paste the reported link, copy the JSON report with its findings and scores, and attach it to the ticket without ever loading the page.

Frequently asked questions

Does this tool visit the URL?

No. Every conclusion comes from the text of the address, worked out in your browser. No request is made to the target, no shortener is expanded, no reputation service is queried, and nothing you paste is sent anywhere.

Why does it say a link is fine when I think it is dangerous?

Because a clean result means no warning signs in the address, which is not the same as a safe destination. A phishing domain registered yesterday with an ordinary-looking name has nothing in its text to give it away. The tool states this explicitly on every clean result rather than implying certainty it does not have.

How does it tell paypal.com from paypa1.com?

It maintains a list of the registered domains major brands genuinely use. When the domain is on that list, the brand name is positive evidence and account pages on it are expected. When a domain merely reads like a brand, the name is folded to the shape the eye sees (the 1 becomes an l) and compared, which identifies it as an imitation rather than the real thing.

Why is an internationalised domain not automatically suspicious?

Because most of them are simply names in a language that needs more than ASCII. The tool decodes the punycode and looks at the characters: one consistent writing system is normal and scores nothing, while a single label mixing Latin with Cyrillic or Greek lookalikes is the actual attack and is flagged.

Why is there no penalty for a .ru or .cn domain?

Because a country suffix says nothing about intent, and scoring it would mostly produce false positives on ordinary foreign sites. What does correlate with abuse is the cost of registration, so suffixes that are free or near-free carry weight regardless of which country they belong to.

Can it catch every phishing attempt?

No, and the limit is structural rather than a matter of tuning. Impersonation, lookalike characters, and structural tricks are visible in the address and are caught reliably. A convincing site on a plainly named domain is not, because there is nothing in the text to see. Against a corpus of 45 synthetic attack patterns the current engine flagged all of them, and against 42 real well-known URLs it flagged none, but a corpus measures the patterns it contains.

Related tools and how they differ

  • SRI Hash Generator: Produces integrity hashes so browsers reject a tampered CDN script or stylesheet; use it to harden your own page, not to judge a link's trustworthiness.
  • CSP Builder: Assembles a Content-Security-Policy that whitelists where your page may load resources; use it to defend your site from XSS, not to check an incoming link.

Private by design

This runs as client-side JavaScript. Keys, tokens, payloads, and other inputs never leave your device.