How to Install Firefox on Debian 13, 12 and 11

Install Firefox on Debian from Mozilla’s APT repository when you want the current stable browser instead of Debian’s long-support Firefox ESR package. The Mozilla package keeps the normal firefox command, adds a desktop launcher, and updates through APT alongside the rest of your system.

Debian includes Firefox ESR as firefox-esr. Use ESR when you prefer Debian’s default long-term browser branch. Use the Mozilla firefox package when you need the current stable release. For preview builds, use the separate Firefox Beta on Debian guide instead of mixing beta commands into this stable setup.

Install Firefox on Debian

Check Your Debian Architecture

Mozilla’s current stable Firefox DEB package is available for amd64 and arm64. Check the system architecture before adding the repository.

dpkg --print-architecture

Continue with this repository method when the output is amd64 or arm64. If the output is i386, Mozilla’s stable firefox package is not published for that architecture; use Debian’s firefox-esr package or Mozilla’s tarball documentation.

Install Required Packages

Install the small tools needed to download the signing key, verify it, and refresh HTTPS package metadata.

sudo apt update
sudo apt install ca-certificates curl gpg

Add the Mozilla Signing Key

Download Mozilla’s repository signing key and store it as an APT-compatible keyring. The --yes option keeps the command safe to rerun if the key file already exists.

curl -fsSL https://packages.mozilla.org/apt/repo-signing-key.gpg | sudo gpg --dearmor --yes -o /usr/share/keyrings/packages.mozilla.org.gpg

Verify the fingerprint before trusting the repository.

gpg --show-keys --with-fingerprint /usr/share/keyrings/packages.mozilla.org.gpg | sed -n '1,2p'

pub   rsa2048 2021-05-04 [SC]
      35BA A0B3 3E9E B396 F59C  A838 C0BA 5CE6 DC63 15A3

The fingerprint must match 35BA A0B3 3E9E B396 F59C A838 C0BA 5CE6 DC63 15A3.

Add the Mozilla APT Source

Create a DEB822 source file for Mozilla’s mozilla suite. This block checks the current architecture first and stops before writing the source file on unsupported systems.

(
  arch=$(dpkg --print-architecture)
  case "$arch" in
    amd64|arm64) ;;
    *)
      printf 'Mozilla stable Firefox DEB packages are not published for %s.\n' "$arch"
      printf 'Use firefox-esr or Mozilla tarball instructions instead.\n'
      exit 1
      ;;
  esac

  printf '%s\n' \
  'Types: deb' \
  'URIs: https://packages.mozilla.org/apt' \
  'Suites: mozilla' \
  'Components: main' \
  "Architectures: $arch" \
  'Signed-By: /usr/share/keyrings/packages.mozilla.org.gpg' | sudo tee /etc/apt/sources.list.d/mozilla.sources > /dev/null
)

Confirm the file before refreshing package metadata. The architecture line should match your system, such as amd64 or arm64.

cat /etc/apt/sources.list.d/mozilla.sources

Types: deb
URIs: https://packages.mozilla.org/apt
Suites: mozilla
Components: main
Architectures: amd64
Signed-By: /usr/share/keyrings/packages.mozilla.org.gpg

Pin Mozilla Firefox Packages

Add an APT preference so Firefox packages from Mozilla’s repository outrank same-named packages from other enabled sources.

printf '%s\n' \
'Package: firefox*' \
'Pin: origin packages.mozilla.org' \
'Pin-Priority: 1000' | sudo tee /etc/apt/preferences.d/mozilla > /dev/null

Check the pin file content.

cat /etc/apt/preferences.d/mozilla

Package: firefox*
Pin: origin packages.mozilla.org
Pin-Priority: 1000

Refresh APT and Install Firefox

Refresh APT so the Mozilla repository becomes available, then install Firefox.

sudo apt update
sudo apt install firefox

Verify the Firefox Package

Confirm that APT sees Mozilla as the Firefox source and that the installed package is present.

apt-cache policy firefox
dpkg-query -W -f='${Package} ${db:Status-Abbrev} ${Version}\n' firefox

The policy output should show https://packages.mozilla.org/apt in the version table, and the dpkg-query status field should show ii.

Check the installed browser version and desktop launcher file.

firefox --version
dpkg -L firefox | grep '/applications/.*firefox.*\.desktop$'

The version command prints Mozilla Firefox followed by the installed stable version, and the package file list should include /usr/share/applications/firefox.desktop.

Install Firefox Language Packs

Mozilla provides optional language packs as firefox-l10n- packages. Search the package list when you need a locale-specific browser interface.

apt-cache search '^firefox-l10n-'

Install the package that matches your language code. For example, use French with firefox-l10n-fr.

sudo apt install firefox-l10n-fr

Replace fr with another available suffix, such as de, ja, or ko, when that locale appears in the search results.

Launch Firefox on Debian

Launch Firefox from the Terminal

Start Firefox from a terminal with the package command.

firefox

Launch Firefox from the Application Menu

On a GNOME desktop, open the application overview and start Firefox from the launcher.

Click Activities in the top-left corner.
Select Show Applications.
Click the Firefox icon.

Update Firefox on Debian

Firefox updates through APT after the Mozilla repository is configured. Use the normal system update path for routine maintenance.

sudo apt update
sudo apt upgrade

To upgrade only Firefox without applying every pending system upgrade, use APT’s package-specific upgrade form.

sudo apt update
sudo apt install --only-upgrade firefox

If you installed a language pack, upgrade it by name as well.

sudo apt install --only-upgrade firefox-l10n-fr

Remove Firefox from Debian

Remove the Firefox Package

Remove the Mozilla Firefox package first. If you installed a language pack, remove that exact package name too.

sudo apt remove firefox
sudo apt remove firefox-l10n-fr

Clean up dependencies that are no longer required.

sudo apt autoremove

Remove the Mozilla APT Source

Remove the repository source, signing key, and APT preference only when no other Mozilla package from this repository should keep receiving updates.

sudo rm -f /etc/apt/sources.list.d/mozilla.sources /usr/share/keyrings/packages.mozilla.org.gpg /etc/apt/preferences.d/mozilla
sudo apt update

If Firefox Beta or another Mozilla repository package is installed from the same source, keep the repository files or remove only the stable firefox package.

Verify Firefox Removal

Check the installed state and remaining package candidates.

dpkg-query -W -f='${Package} ${db:Status-Abbrev} ${Version}\n' firefox 2>/dev/null || true
apt-cache policy firefox

After repository cleanup, apt-cache policy firefox should no longer show packages.mozilla.org. If it still appears, another source file still points at Mozilla’s repository.

Remove Firefox User Data

Firefox profile data stays in your home directory after package removal. Delete it only when you want to remove bookmarks, history, saved passwords, extensions, and cache files from this Linux account.

Warning: These commands permanently delete Firefox profile data for your user. Export bookmarks and back up anything important before running them.

rm -rf ~/.mozilla/firefox
rm -rf ~/.cache/mozilla/firefox

Troubleshoot Firefox on Debian

APT Reports a Duplicate Mozilla Source

Use only one Mozilla APT source. Older extrepo-based setups can point at the same repository as the manual mozilla.sources file, and duplicate entries can cause APT source or Signed-By conflicts.

grep -R "packages.mozilla.org/apt" /etc/apt/sources.list.d

If you see both extrepo_mozilla.sources and mozilla.sources, keep the manual Mozilla source created earlier and disable the extrepo entry.

if command -v extrepo >/dev/null 2>&1; then
  sudo extrepo disable mozilla
fi
sudo rm -f /etc/apt/sources.list.d/extrepo_mozilla.sources /var/lib/extrepo/keys/mozilla.asc
sudo apt update

For broader extrepo cleanup patterns, use the Debian third-party APT repository management guide.

APT Cannot Verify the Mozilla Repository

A keyring error usually means the Mozilla key file is missing, corrupt, or written in a format APT cannot use.

Err:4 https://packages.mozilla.org/apt mozilla InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C0BA5CE6DC6315A3

Recreate the keyring, verify the fingerprint, and refresh APT.

curl -fsSL https://packages.mozilla.org/apt/repo-signing-key.gpg | sudo gpg --dearmor --yes -o /usr/share/keyrings/packages.mozilla.org.gpg
gpg --show-keys --with-fingerprint /usr/share/keyrings/packages.mozilla.org.gpg | sed -n '1,2p'
sudo apt update

Firefox Has No Installation Candidate

If APT cannot find firefox, check the architecture and repository file first.

dpkg --print-architecture
cat /etc/apt/sources.list.d/mozilla.sources
apt-cache policy firefox

On amd64 or arm64, the source file should contain URIs: https://packages.mozilla.org/apt, Suites: mozilla, and an Architectures: line matching the host architecture. On i386, use firefox-esr from Debian instead because Mozilla’s stable firefox DEB package is not published for that architecture.

Related Firefox and Debian Guides

Mozilla Linux installation documentation: Official source for Mozilla’s Linux package methods, language packs, tarball instructions, and profile migration notes.
Firefox official website: Release information, downloads, and browser feature details.
Install Firefox Beta on Debian: Use the preview channel when you need pre-release Firefox builds.
Install Brave Browser on Debian: Add a Chromium-based browser with its own vendor repository.
Install Chromium Browser on Debian: Use Debian’s Chromium package when you want an open-source Chromium-family browser.

Conclusion

Firefox is now installed on Debian from Mozilla’s APT repository, with the signing key, DEB822 source, package pin, update path, launcher check, and cleanup steps handled in one source layout. Keep Debian’s firefox-esr when long-term stability matters more than current stable releases, and keep preview channels in their own setup so stable and beta package sources stay easy to audit.