● Open source · Local-first · No telemetry

Close the session.
Keep the access.

FURSOY Vault removes selected session cookies from your browser, seals them in an encrypted vault on your own machine, and restores them only once you verify it is you.

Get the extension ↓Explore the source

Chromium browsers on Windows 10/11 and Linux

⌕ accounts.example.com
F
Protected session

Your session is sealed.

The site’s cookies have left the browser and are encrypted in a vault on your own machine.

● Waiting for you to verify it’s you
FURSOY VaultCompanion connected
Active
Current siteaccounts.example.com
Protected
E
example.com3 active cookies
Profile · PersonalOpen vault settings →
LOCALNo account. No cloud vault.
EXPLICITYou choose every protected site.
ISOLATEDSeparate identity per browser profile.
OPENGPL-3.0 source, publicly inspectable.
How it works

A deliberate pause between
your browser and your session.

Protection is simple enough to use every day, but intentionally requires you when a locked session returns.

01
＋

Choose a site

Add a domain from the extension. FURSOY Vault asks your browser only for that site’s permission.

02
⌁

Seal its session

Matching cookies leave the browser and enter the encrypted vault held by the companion app on your machine.

03
✓

Approve the return

When you revisit, your face, fingerprint or PIN is checked before the session cookies come back.

Security architecture

Trust should come from boundaries,
not a promise.

Every important boundary is visible in the design and documented in the repository.

01

Local by design

Session cookies are encrypted and stored on this device—not uploaded to a FURSOY account or cloud.

02

Approval by you

Restoring a session takes Windows Hello on Windows, or a PIN held by the TPM on Linux. Neither the gesture nor the PIN reaches the extension.

03

Profile isolation

Each browser profile gets its own vault identity, recovery view and protected-site scope.

04

Fail-closed behavior

If the companion, permission or integrity checks fail, the vault does not silently expose the session.

05

Minimal site access

Host permission is requested only for the domains you choose to protect, and can be revoked at any time.

06

Inspectable, redacted audit

Local diagnostics retain security events for 90 days while excluding cookie values and secrets.

BROWSER PROFILESelected cookies
→
LOCAL COMPANIONEncrypted local vault
→
USER PRESENCEYour approval
Honest scope

One focused layer.
Not a magic shield.

FURSOY Vault reduces the risk of an unattended, already-signed-in browser session. It does not claim to protect a compromised computer account or replace the security controls around it.

Read the complete threat model

✓ Designed to protect

  • Selected browser session cookies
  • Unattended signed-in sessions
  • Separation between browser profiles
  • Local recovery with explicit ownership

× Outside its boundary

  • Passwords and passkeys
  • localStorage and IndexedDB
  • Malware already running as you
  • Browser history and downloaded files
Open source

Security you can inspect.

The Chrome extension, Rust companion, protocol, threat model, release checks and test suites are public. There is no hidden service behind the product. It is built and maintained by one person, and sponsorship goes first to the Windows code-signing certificate that would remove the Unknown publisher warning from every install.

Browse the repository Sponsor the projectPrivacy policy
security-boundaries.txt
$ data_location        this_device_only
$ telemetry            disabled
$ profile_scope        isolated
$ restore_approval     windows_hello
$ failure_mode         fail_closed
✓ Documented and testable
Common questions

Know what you are installing.

Does FURSOY Vault upload my cookies?＋

No. Cookie values are processed locally between the browser extension and the companion app on your machine. The project has no analytics or telemetry service.

What happens when I lock a protected site?＋

Its matching cookies are removed from the browser and stored in the encrypted local vault. Once you verify it is you, they are restored to that browser profile.

Does it protect every kind of browser data?＋

No. FURSOY Vault protects selected cookies. It is not a password manager and does not currently vault localStorage, IndexedDB, downloads or browser history.

Which platforms are supported?＋

Chromium browsers—Chrome, Edge, Brave and the rest—on Windows 10/11 or Linux, with the companion app installed. Windows needs a Windows Hello method on the account; Linux uses a PIN held by a TPM 2.0 chip.

FURSOY Vault iconReady when you are

Put your open sessions
behind your presence.

Review the source, understand the boundary, then install FURSOY Vault for your browser.

Get the extension ↓GitHub