Privacy & Leaks

Does your VPN actually hide you? These tests look for the leaks VPNs miss.

IP …
Location …
ISP …

DNS Leak

Color key Green — healthy / above target Blue — normal / neutral info Amber — below target, worth a look Red — leak or serious problem Grey — not run yet

Who resolves your website lookups?

DNS resolver ASN vs. declared VPN ASN — mismatch = leak.

Fix this

WebRTC Leak

Color key Green — healthy / above target Blue — normal / neutral info Amber — below target, worth a look Red — leak or serious problem Grey — not run yet

Some sites can see your real IP even with a VPN.

RTCPeerConnection ICE candidate scan for local + public IPs.

Fix this

VPN / Proxy Signal

Color key Green — healthy / above target Blue — normal / neutral info Amber — below target, worth a look Red — leak or serious problem Grey — not run yet

Does your connection look like a VPN?

Hosting-ASN heuristic + tz/ip mismatch + known VPN ranges.

Fix this

IPv6 Reachability

Color key Green — healthy / above target Blue — normal / neutral info Amber — below target, worth a look Red — leak or serious problem Grey — not run yet

Do you have the newer internet protocol?

Dual-stack reachability probe with fallback.

Fix this

Timezone Mismatch

Color key Green — healthy / above target Blue — normal / neutral info Amber — below target, worth a look Red — leak or serious problem Grey — not run yet

Does your clock match where your IP says you are?

Intl.DateTimeFormat().resolvedOptions().timeZone vs. geo-IP TZ.

Fix this

DNS Leak

What is this?

Every time you type a domain name like example.com, your device has to ask a DNS resolver to translate that into an IP address. This test compares two answers: (1) the IP + country we see for the request that hit our server, and (2) the Cloudflare edge that answered a DNS-style trace from your browser. If those two look like they belong to very different networks or countries, your DNS is being handled by a resolver that is not on the path you probably think it is -- classic symptom of a VPN or DNS-over-HTTPS setup that is only partially covering your traffic.

So what?

A DNS leak is a privacy problem because your resolver sees the name of every site you visit before any HTTPS encryption kicks in. If you are paying for a VPN specifically for privacy, and your DNS queries are still going to your ISP or to Google, then your ISP still has a full log of the domains you browse -- the VPN is only hiding the content, not the destinations. It also breaks censorship-resistance: a hostile network can silently redirect DNS answers even when the rest of your traffic looks encrypted.

Now what?

If this card flags a mismatch: adjust your VPN client to force DNS through the tunnel, enable Secure DNS in your browser, and re-run this test.

Deep dive tutorial DNS leaks: what your "phone book" lookups reveal about you Back to top

WebRTC Leak

What is this?

WebRTC is the peer-to-peer video/audio API built into every modern browser (it is what powers Google Meet, Discord voice, and a lot of "click-to-call" widgets). To let two peers connect directly, WebRTC uses a protocol called ICE (Interactive Connectivity Establishment) that asks the operating system for every possible way you can be reached. That normally includes: your public IP (the one you already announce to every website anyway), your LAN address (192.168.x.x, useful for two devices on the same Wi-Fi), and -- the risky one -- your VPN-bypassed real IP if you are on a VPN. Any page can trigger this lookup silently, with no permission prompt, and read the answer back with JavaScript.

So what?

This is the single most common way VPN users get de-anonymized without realizing it. Your VPN tunnel is doing its job for HTTP traffic, but WebRTC is bypassing it at the OS level and telling every ad tracker on the page your true home IP. That IP alone is enough to place you inside a city, and combined with browser fingerprinting it is often enough to tie an "anonymous" browsing session back to a residential subscriber. Chrome, Edge, Opera, and Brave all leak by default; Firefox and Safari are safer but not immune.

Now what?

If an extra IP is exposed, adjust your browser's WebRTC settings to stop it from bypassing your VPN.

Deep dive tutorial WebRTC leaks: the browser feature that can reveal your real IP Back to top

VPN / Proxy Signal

What is this?

We look up the organization and Autonomous System Number (ASN) that owns your public IP, then classify it. Residential ISPs (Comcast, Cincinnati Bell, Verizon FiOS, etc.) look very different in the routing tables from hosting providers (DigitalOcean, OVH, Hetzner) and from named commercial VPNs (Mullvad, ProtonVPN, NordVPN). If your traffic is exiting from an org that is clearly a datacenter or a known VPN provider, we flag it -- the "confidence" is a rough score based on how many hosting/VPN hints match.

So what?

This is the same lookup that streaming services, banks, ticket sites, and fraud-detection systems run when they decide whether to challenge you with a captcha or a "we noticed a login from a new location" email. Even if you are using a VPN for legitimate privacy reasons, more and more sites now treat any datacenter IP as automatically suspicious and either block you or slow-lane you into extra verification. On the flip side, if you expect to be on a VPN and this card says "Residential," your VPN tunnel is either off or leaking -- worth investigating alongside the DNS Leak and WebRTC Leak cards on this same page.

Now what?

If you WANT to look residential, use split-tunneling or a residential-proxy service. If you WANT to look private, pick a no-logs-audited VPN and pair with Tor Browser for the highest-risk sessions.

Deep dive tutorial How websites spot a VPN, and what you can honestly do about it Back to top

IPv6 Reachability

What is this?

The internet is slowly running out of the old 32-bit IPv4 addresses (roughly 4 billion possible, and we blew past that years ago). IPv6 is the 128-bit replacement, and roughly 45% of Google traffic worldwide now arrives over it. This card asks two questions: does your connection have any IPv6 address at all, and is that address globally routable (dual-stack) vs a link-local one that only works on your LAN?

So what?

IPv6 is faster in many cases because there is less NAT (Network Address Translation) between you and the destination -- your device gets a real, unique address instead of sharing one with the rest of your household. It also matters for gaming, video calls, and any peer-to-peer app: two IPv6 hosts can talk directly, while two IPv4 hosts behind NAT usually need a relay server in the middle, which adds latency. On the privacy side, IPv6 addresses are much larger and are often assigned per-device, so cross-site tracking based on IP is actually easier on IPv6 unless your ISP is rotating your prefix.

Now what?

IPv4-only is common on US home connections. Enable IPv6 in your router or ask your ISP if you want it.

Deep dive tutorial IPv6 for humans: what it is and why you probably want it on Back to top

Timezone Mismatch

What is this?

Your browser reports a timezone (via the JavaScript Intl API) that is set by your operating system -- for a Cincinnati user, that should read "America/New_York". Separately, your IP address geolocates to a country and city, and every country/city has an expected timezone. This card compares the two. A mismatch means the browser is telling websites you are in one place while your network exit says you are in another.

So what?

Picture this: you sign into a streaming service through a VPN so you can watch something not available in your country. The IP looks like it is in the right country -- the VPN did its job. But your browser is still telling every page you visit that your computer clock is set to Eastern Time (because your OS never changed). The streaming service compares the two, sees the mismatch, and either blocks your stream, forces a re-login, or downgrades you to the local catalog. This is the single cheapest, most common way anti-fraud and geo-blocking systems catch VPN users -- your IP can be perfect, but your timezone gives you away in one line of JavaScript. It is also a top-three fingerprinting signal for ad networks even when you are not on a VPN, because a consistent IP + timezone across sessions is a stable identifier they can key on.

Now what?

If this flags and you are not on a VPN, your OS clock is stuck on an old zone -- fix it in system settings. If you are on a VPN and want consistency, either match your OS timezone to the VPN exit or use a per-site timezone-spoofer extension.

Deep dive tutorial Timezone mismatch: the clock that quietly gives away your VPN Back to top