Phalcon is a C extension, so you need to download a binary for your platform or compile it from source code.

Ubuntu or Debian

To install Phalcon on Ubuntu or Debian you need to follow these steps: 

curl -s "https://packagecloud.io/install/repositories/phalcon/stable/script.deb.sh" | sudo bash

sudo apt-get install php5-phalcon

# Ubuntu 16.04+, Debian 9+
sudo apt-get install php7.0-phalcon

If you wish to install the legacy version of Phalcon (1.x) use the following PPA: 

sudo apt-add-repository ppa:phalcon/legacy

If you are missing apt-add-repository run the following command: 

# Ubuntu 14.04+
sudo apt-get install software-properties-common

# Ubuntu 12.04
sudo apt-get install python-software-properties

Compilation

On Linux you can easily compile and install the extension from source code.

Requirements

We need some packages previously installed: 

# Ubuntu
sudo apt-get install php5-dev php5-mysql gcc libpcre3-dev

# Fedora
sudo dnf install php-devel php-mysqlnd gcc libtool pcre-devel re2c

# RHEL
sudo yum install php-devel php-mysql gcc libtool pcre-devel

# Suse
yast2 -i php5-pear php5-devel php5-mysql gcc libtool pcre-devel

# macOS (Homebrew)
brew tap homebrew/dupes
brew tap homebrew/versions
brew tap homebrew/php
brew install php5x php5x-phalcon # php55, php56, ...

# macOS (MacPorts)
sudo port install php73-phalcon # php72, php71, php56, ...

Compilation

1. To create the extension from C source follow these steps: 

git clone --depth=1 "git://github.com/phalcon/cphalcon.git"
cd cphalcon/build
sudo ./install

2. Add the extension to your php.ini: 

extension=phalcon.so

3. Finally, restart the webserver

Arch Linux

There is a PKGBUILD for ArchLinux, available here

OpenSUSE

There is a package available here (thanks to Mariusz Łączak)

FreeBSD

A port is available for FreeBSD. You only need these few commands to install it: 

pkg_add -r phalcon

or

cd /usr/ports/www/phalcon && make install clean

cPanel

After requests from the community, the cPanel developers released a custom module that allows for installation of Phalcon in cPanel hosted sites. Information can be found here. The module is maintained in Github.

Dependencies

Although Phalcon does not binary link to other extensions it does use some of them to offer functionality. The extensions used are:

It is not necessary for all the above extensions to be present in the system that has Phalcon installed. You can only install the ones that meet your needs. For instance if you use a MySQL database, then you can only load PDO and PDO/MySQL ignoring the Oracle, SQlite, Postgresql and Mongo.

Have a look at our support page for ways to get support. We will do our best to help you.