Awesome GUI Password Manager.

• Install using apt:

  sudo apt install keepassxc

• Download the AppImage, GPG Key, and SHA Digest: https://keepassxc.org/download/
• Import KeePassXC's gpg signing key:

  gpg --fetch-keys https://keepassxc.org/keepassxc_master_signing_key.asc

• GPG Verify the signature file:

  gpg --verify KeePassXC-*.sig

• Verify integrity of the AppImage:

  sha256sum -c KeePassXC-*.AppImage.DIGEST

• Move the AppImage to somewhere in your $PATH:

  mv ~/Downloads/KeePassXC-*.AppImage ~/.local/bin/keepassxc

• Make the AppImage executable:

  chmod u+x ~/.local/bin/keepassxc

• Create a .desktop file:

  [Desktop Entry]
  Name=KeePassXC
  GenericName=Community Password Manager
  Exec="keepassxc" %U
  Icon=appimagekit-keepassxc
  Terminal=false
  Type=Application
  Categories=Qt;Utility;
  MimeType=application/x-keepass2;
  X-Desktop-File-Install-Version=0.22

• Here's a script I wrote to install/update the AppImage:

  #!/usr/bin/env bash
   
  latest="https://api.github.com/repos/keepassxreboot/keepassxc/releases/latest"
   
  # Import keepassxc's gpg key
  if ! gpg --list-keys 0xCFB4C2166397D0D2; then
    gpg --fetch-keys https://keepassxc.org/keepassxc_master_signing_key.asc
  fi
   
  printf '\n%b\n\n' "\e[1;34mDownloading the files.\e[0m"
   
  # Download the files
  curl -s "$latest" | awk -F': ' '/browser_download_url/ && /\.AppImage/ && !/zsync/ {gsub(/"/, "", $(NF)); system("curl -LO " $(NF))}'
   
  # Verify and install the appimage
  printf '\n%b\n\n' "\e[1;34mVerifying the files.\e[0m"
  if shasum -c KeePassXC-*.AppImage.DIGEST; then
    if gpg --verify KeePassXC*.AppImage.sig KeePassXC*.AppImage; then
      mv -f KeePassXC*.AppImage ~/.local/bin/keepassxc && \
      chmod +x ~/.local/bin/keepassxc && \
      pkill -f keepassxc && \
      gtk-launch keepassxc.desktop && \
      rm -f KeePassXC*.AppImage*
    else
      printf '\n%b\n' "\e[1;31m[ERROR] Problem with signature!\e[0m"
    fi
  else
    printf '\n%b\n' "\e[1;31m[ERROR] Problem with checksum!\e[0m"
  fi

There's a small difference in using the keepassxc-cli depending on the method used to install. Note the hyphen - usage.

• Installed using the apt instructions above:

  keepassxc-cli help

• Installed using the AppImage instructions above:

  keepassxc cli help

• https://keepassxc.org
• https://keepassxc.org/verifying-signatures/
• https://keepassxc.org/docs/KeePassXC_UserGuide.html
• https://packages.debian.org/bullseye/keepassxc
• https://manpages.debian.org/testing/keepassxc/keepassxc.1.en.html
• https://manpages.debian.org/unstable/keepassxc/keepassxc-cli.1.en.html