Tor Browser

ApplicationThe Tor Project

Also called tor, torbrowser, the onion router browser

The Tor ProjectBrowsers

A Firefox ESR fork from the Tor Project that routes traffic over the Tor network. On Windows the process is firefox.exe.

What you need to know

Tor Browser is a Firefox ESR fork that uses Tor. Stock Firefox does not.

The Tor Project ships a hardened Firefox ESR that connects through Tor circuits. The process name is firefox.exe. Stock Mozilla Firefox is a different install and does not onion-route your tabs.

What is it?: Firefox ESR that uses the Tor network
Same as Firefox?: No. Different build and traffic path
Same as Mullvad Browser?: No. Mullvad does not use Tor

Feex says

If I see firefox.exe under a Tor Browser folder, I treat it as Tor, not Mozilla Firefox. I would not "fix" it by installing stock Firefox on top.

What is Tor Browser?

Tor Browser is the Tor Project's Firefox ESR-based browser. It starts a Tor client and sends browser traffic over Tor. The window process is firefox.exe inside the Tor Browser folder.

If you have never used it

If you need the Tor network in a browser, this is Tor Browser, not stock Firefox. Download it from torproject.org/download. It is a Firefox ESR fork that builds circuits through Tor. Sites see a Tor exit, not your home IP. Mullvad Browser looks similar and does not use Tor. Stock Firefox from mozilla.org is a different product.

What is it used for?

Browse over Tor

HTTP(S) through Tor circuits. This is the product job. Stock Firefox does not do this.

Onion sites

.onion addresses the Tor client can reach. A normal browser cannot open those without extra software.

Fingerprint-resistant defaults

Window size, letterboxing, and NoScript-style defaults the Tor Project ships. They can break some sites on purpose.

Who is it for?

People who were told to use Tor Browser, not "Firefox plus a VPN"
Users who need .onion reachability
Anyone who saw firefox.exe and assumed Mozilla Firefox

Current status

Actively developed. Releases follow Firefox ESR plus Tor Project patches. This article is the Windows desktop bundle.

How old is it?

The Tor Project shipped a dedicated browser bundle in 2008. Firefox itself is older. Current Tor Browser is still an ESR fork, not a Chromium reskin. A 2004 "Privoxy plus Firefox" guide is not this installer.

Versions

Major channels first. Exact build numbers are not all verified here.

Stable

Alpha

System requirements

Values follow the publisher's public guidance. Workload still changes the real need.

Minimum

Minimum system requirements
CPU	A 64-bit processor current Tor Browser lists for Windows
RAM	2 GB class can start it. Circuits and content processes want more
Operating system	Windows 10 or Windows 11, per the Tor Project install docs

Resource profile

CPU demand: Circuit setup plus the page
RAM demand: Firefox content processes
Network demand: Tor is slower than a direct connection. That is expected

Installed processes

These executables belong to this product when it is installed.

Installed processes
firefox.exe	Tor Browser window and content processes
tor.exe	Tor client the bundle starts

Startup components

Tor Browser is not meant to sit in Windows Startup. You launch it when you want a Tor session. It does not replace your default browser unless you set that.

File locations

Common Tor Browser locations
Typical portable-style folder	A Tor Browser folder you chose, often under the user profile
Do not confuse with	C:\Program Files\Mozilla Firefox\

File formats

HTMLPDFPNGJPEG

Common problems

Sites break or look letterboxed

Security level and fingerprint defenses shrink the canvas. That is Tor Browser, not a GPU failure.

People update Firefox and break the bundle

Do not overwrite this firefox.exe with Mozilla's installer. Update from the Tor Project.

Getting unstuck

Confirm the folder is Tor Browser

firefox.exe next to a Tor Browser Start Tor Browser shortcut is this product. Program Files\Mozilla Firefox is stock Firefox.

Use the onion button and circuit display

A new circuit is a Tor Browser control. Changing Windows proxy settings by hand is the wrong first step.

Download only from torproject.org/download

Fake Tor installers are a long-running scam. Verify the signature the manual describes.

Alternatives

Mullvad Browser if you want the same hardening without Tor. Stock Firefox if you want a normal Gecko browser. A VPN app is not a Tor Browser replacement.

Official help and downloads

Start with the vendor. Random exe sites are not a support channel.

Official contacts
Download	www.torproject.org/download/ Official Windows package
User Manual	tb-manual.torproject.org/ Install, verify, and security levels
Support portal	support.torproject.org/ Circuits, bridges, and errors
Project site	www.torproject.org/ What the Tor Project ships

Related hardware

A modest CPU is enough. The delay is usually the Tor path, not a missing gaming GPU.

Technical details

ESR-based version numbers change on the Tor Project train. This article does not pin a build.

Sources and verification

Reviewed by Feex editorial. Last verified August 2026 Status: Feex Reviewed. How we research.

Tor Browser download · Official Windows package
Tor Browser User Manual · Official manual
Foxhole process map · First-party samples on Windows PCs. Not a lab benchmark.

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