Erlang/OTP 21.2 is the second service release containing mostly bug fixes and characteristics improvements but also a few features.

OTP 21.2 Readme File

OTP 21.2 Source File (89929318)

OTP 21.2 Windows 32-bit Binary File (89929318)

OTP 21.2 Windows 64-bit Binary File (92193047)

OTP 21.2 HTML Documentation File (32798331)

OTP 21.2 Man Pages File (1325975)

OTP 21.2

Erlang/OTP 21.2 is the second service release for the 21st major release with, improvements as well as a few features!




  • Public key methods: ssh-ed25519 and ssh-ed448 added. Requires OpenSSL 1.1.1 or later as cryptolib under the OTP application


  • ssl now uses active n internally to boost performance. Old active once behaviour can be restored by setting a application variable.

ERTS, Kernel:

  • New counters and atomics modules supplies access to highly efficient operations on mutable fixed word sized variables.
  • New module persistent_term!. Lookups are in constant time! No copying the terms!
  • New pollset made to handle sockets that use {active, true} or {active, N}. Polled by a normal scheduler!

  • No more ONESHOT mechanism overhead on fds! Only on Linux and BSD

Online documentation can be browsed here:

The Erlang/OTP source can also be found at GitHub on the official Erlang repository, Here: OTP-21.2

Please report any new issues via Erlang/OTPs public issue tracker

We want to thank all of those who sent us patches, suggestions and bug
Thank you!
The Erlang/OTP Team at Ericsson

Compiling Erlang from source

You can build Erlang from source on your own, following the building and installation instructions. Or use the Kerl script. Kerl is a script that lets you easily build Erlang with a few commands. Follow the instructions to build.

Finding a source version

Follow this link that presents all released source versions, a link to the GitHub source tag, and to the README.

Pre-built Binary Packages

Most OS package managers provide pre-built binary packages. You can also download the latest stable releases from Erlang Solutions. Erlang Solutions provides pre-built binary packages for OS X, Windows, Ubuntu, Debian, Fedora, CentOS, Raspbian and other operating systems. 

  • For Homebrew on OS X: brew install erlang
  • For MacPorts on OS X: port install erlang
  • For Ubuntu and Debianapt-get install erlang
  • For Fedorayum install erlang
  • For FreeBSDpkg install erlang


Since OTP 18.0, Erlang/OTP is released under Apache License 2.0. The older releases prior to 18.0 were released under Erlang Public License (EPL), a derivative work of the Mozilla Public License (MPL).