Get the desktop app
The fastest way to get started. Register for a license and download the app. That's all. Profiles are managed through the interface. No terminal required.
Browser Fingerprinting
404 Not Found.
404 replaces your browser fingerprint so your online behavior can't be linked back to you.
- Open source
- No accounts required
- No data collection
This is what websites can see about you at all times This information can be used to recognize you across sites even if you never log in.
Standby
Reading your browser's fingerprint
Browser —
Timezone —
Device —
OS —
Screen — (try zooming)
Canvas hash —
Language —
WebGL renderer —
These values combine into the browser fingerprint sites use to recognize this device.
4,000+
companies tracking you right now
404 prevents tracking
Commercial services can uniquely identify over 99% of users. VPNs mask your IP address. That's a real benefit, but it's one signal out of hundreds. Your fingerprint is identical whether you're on a VPN, in incognito mode, or on a different network.
Screen size, fonts, graphics hardware, audio processing, installed languages. Combined, they form a fingerprint more precise than your IP address. Cookies and logins are not required.
How it works
Local software. No cloud. No extensions.
404 runs locally between your browser and the sites you visit. It rewrites the fingerprinting signals exposed across TLS, HTTP, JavaScript, and TCP/IP, then applies them consistently for that session so the next one has no connection to the last.
Self-host it
404 is open source (AGPLv3). Run it yourself and manage your own profiles. Full documentation covers installation, configuration, and usage.
No account. No telemetry. No data leaves your machine. See the full architecture
404 Audit
How recognizable is your organization online?
404 Audit is a scoped exposure assessment for teams that need to know whether browsers, networks, or research workflows remain linkable after privacy controls are applied.
What you get
- Cross-session exposure testing across real browsing and network conditions
- A risk assessment showing what remains stable enough to support attribution
- Suggested mitigations and training options for the workflows that matter
Who it's for
Built for work where exposure has consequences.
404 is for people whose browser identity can expose research, clients, sources, or staff.
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Journalists
Read use caseReporting patterns leave a fingerprint trail that can connect your browser identity to investigations, sources, and your newsroom across sessions.
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Legal professionals
Read use caseCase research builds a recognizable browser profile that can expose repeated activity, work product focus, or client matters to the sites you're visiting.
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Research organizations
Read use caseTeams monitoring the same sites repeatedly become easier to identify over time, even when IP addresses and networks change between sessions.
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Human rights organizations
Read use caseFor staff operating across borders or in hostile jurisdictions, a stable browser identity is an operational security risk, not just a privacy one.
Open source
Don't trust us. Verify.
404 is open source (AGPLv3). The code is public and auditable. We don't collect data, we don't phone home, and we don't require accounts. It's browser fingerprint protection software you can inspect yourself.
Verify it yourself
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Need rollout, support, or pricing details instead? info@404privacy.com