Packages
Arch Linux: pacman -S otter-browser
Ubuntu PPAs: https://launchpad.net/~otter-browser
Many Linux distributions: AppImage on https://sourceforge.net/projects/otter-browser/files
ROSA Linux: urpmi otter-browser
https://abf.rosalinux.ru/import/otter-browser / https://abf.rosalinux.ru/rosalinuxro/otter-browser
Mageia: urpmi otter-browser
OpenBSD: pkg_add otter-browser
Beta releases are officially packaged for OpenBSD by the Otter porting team. You can obtain the latest beta release by issuing the command provided above.
FreeBSD: pkg install otter-browser
Official packages are maintained by the KDE/FreeBSD team.
Gentoo: emerge www-client/otter
https://packages.gentoo.org/packages/www-client/otter
OpenMandriva Lx 3 and older urpmi otter-browser
OpenMandriva Lx 4/Cooker and newer dnf install otter-browser
Packages in OpenMandriva ABF (Automated Build Farm). OpenMandriva Build sources (spec files).
CentOS/EL 7: Enable nux-dextop repo then yum install otter-browser (backported from Fedora)
Fedora: https://admin.fedoraproject.org/pkgdb/package/rpms/otter-browser (by martinkg)
Haiku offers packages for Otter Browser in HaikuPorts that are easily installable through HaikuDepot.
openSUSE: http://software.opensuse.org/package/otter-browser (by Fisiu and malcolmlewis)
SparkyLinux: Add Sparky (https://repo.sparkylinux.org) repo then apt-get install otter-browser
VoidLinux: xbps-install otter-browser Template for otter-browser
Mac OS X: 10.7+ only. You should disable Gatekeeper by Allowing applications from anywhere to install. Mac OS X Packages (by BugraK) unmaintained since beta 8
If you have created packages and want to include links to them here then please notify me, preferred way is to ping Emdek at #otter-browser at freenode.