Get the desktop app
The fastest way to get started. Download the app, install the local certificate, and point your browser at the proxy. Profiles are managed through the interface. No terminal required.
Take back your privacy
Your browser remembers what you shop for, who you talk to, and where you go online.
404 stops websites from building a fingerprint of your browser and tracking you across the web.
You're not as private as you think.
- Open source
- No accounts required
- No data collection
What browsers can see about you
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 —
Device —
OS —
Language —
Screen — (try zooming)
Timezone —
Canvas hash —
WebGL renderer —
These values combine into the browser fingerprint sites use to recognize this device.
Why use 404?
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
A local proxy. 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 under the AGPL. Run it yourself, build from source, and manage your own profiles. Full documentation covers installation and configuration.
No accounts. No telemetry. No data leaves your machine. See the full architecture
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 under the AGPL license. Every line of code is 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. A privacy tool that requires trust isn't a privacy tool.
Verify it yourself
404 Blog
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Need rollout, support, or pricing details instead? [email protected]