I tend to use Homebrew on Mac. It will install and configure all the stuff for you.
Link

Then you should be able to install it with brew install mcrypt php53-mcrypt and it'll Just Work (tm).

You can replace the 53 with whatever version of PHP you're using, such as php56-mcrypt or php70-mcrypt. If you're not sure, use brew search php.

Do also remember that if you are using the built in Mac PHP it's installed into /usr/bin you can see which php you are using with which php at the terminal and it'll return the path.

I just went through this on Mountain Lion. Homebrew blocked on libiconv which it thought was missing but was actually up to date. After an hour of trying to get it to recognize libiconv, I gave up and installed it the old fashion way, which took all of five minutes...

(download your php version) $ wget http://www.php.net/get/php-5.3.21.tar.gz/from/a/mirror $ tar -xvzf php-5.3.21.tar.gz $ cd php-5.3.21/ext/mcrypt $ phpize $ ./configure $ make $ make test $ sudo make install 

mcrypt.so is now in your PHP ext dir (/usr/lib/php/extensions/no-debug-non-zts-20090626/ in my case), now you need to add to php.ini as a module

$ vi /etc/php.ini $ (insert) extension=mcrypt.so $ sudo apachectl restart 

Done - no brew necessary. HTH someone.

Installing php-mcrypt without the use of port or brew

Note: these instructions are long because they intend to be thorough. The process is actually fairly straight-forward. If you're an optimist, you can skip down to the building the mcrypt extension section, but you may very well see the errors I did, telling me to install autoconf and libmcrypt first.

I have just gone through this on a fresh install of OSX 10.9. The solution which worked for me was very close to that of ckm - I am including their steps as well as my own in full, for completeness. My main goal (other than "having mcrypt") was to perform the installation in a way which left the least impact on the system as a whole. That means doing things manually (no port, no brew)

To do things manually, you will first need a couple of dependencies: one for building PHP modules, and another for mcrypt specifically. These are autoconf and libmcrypt, either of which you might have already, but neither of which you will have on a fresh install of OSX 10.9.

autoconf

Autoconf (for lack of a better description) is used to tell not-quite-disparate, but still very different, systems how to compile things. It allows you to use the same set of basic commands to build modules on Linux as you would on OSX, for example, despite their different file-system hierarchies, etc. I used the method described by Ares on StackOverflow, which I will reproduce here for completeness. This one is very straight-forward:

$ mkdir -p ~/mcrypt/dependencies/autoconf $ cd ~/mcrypt/dependencies/autoconf $ curl -OL http://ftpmirror.gnu.org/autoconf/autoconf-latest.tar.gz $ tar xzf autoconf-latest.tar.gz $ cd autoconf-*/ $ ./configure --prefix=/usr/local $ make $ sudo make install 

Next, verify the installation by running:

$ which autoconf 

which should return /usr/local/bin/autoconf

libmcrypt

Next, you will need libmcrypt, used to provide the guts of the mcrypt extension (the extension itself being a provision of a PHP interface into this library). The method I used was based on the one described here, but I have attempted to simplify things as best I can:

First, download the libmcrypt source, available from SourceForge, and available as of the time of this writing, specifically, at:

http://sourceforge.net/projects/mcrypt/files/Libmcrypt/2.5.8/libmcrypt-2.5.8.tar.bz2/download

You'll need to jump through the standard SourceForge hoops to get at the real download link, but once you have it, you can pass it in to something like this:

$ mkdir -p ~/mcrypt/dependencies/libmcrypt $ cd ~/mcrypt/dependencies/libmcrypt $ curl -L -o libmcrypt.tar.bz2 '<SourceForge direct link URL>' $ tar xjf libmcrypt.tar.bz2 $ cd libmcrypt-*/ $ ./configure $ make $ sudo make install 

The only way I know of to verify that this has worked is via the ./configure step for the mcrypt extension itself (below)

building the mcrypt extension

This is our actual goal. Hopefully the brief stint into dependency hell is over now.

First, we're going to need to get the source code for the mcrypt extension. This is most-readily available buried within the source code for all of PHP. So: determine what version of the PHP source code you need.

$ php --version # to get your PHP version 

now, if you're lucky, your current version will be available for download from the main mirrors. If it is, you can type something like:

$ mkdir -p ~/mcrypt/php $ cd ~/mcrypt/php $ curl -L -o php-5.4.17.tar.bz2 http://www.php.net/get/php-5.4.17.tar.bz2/from/a/mirror 

Unfortunately, my current version (5.4.17, in this case) was not available, so I needed to use the alternative/historical links at http://downloads.php.net/stas/ (also an official PHP download site). For these, you can use something like:

$ mkdir -p ~/mcrypt/php $ cd ~/mcrypt/php $ curl -LO http://downloads.php.net/stas/php-5.4.17.tar.bz2 

Again, based on your current version.

Once you have it, (and all the dependencies, from above), you can get to the main process of actually building/installing the module.

$ cd ~/mcrypt/php $ tar xjf php-*.tar.bz2 $ cd php-*/ext/mcrypt $ phpize $ ./configure # this is the step which fails without the above dependencies $ make $ make test $ sudo make install 

In theory, mcrypt.so is now in your PHP extension directory. Next, we need to tell PHP about it.

configuring the mcrypt extension

Your php.ini file needs to be told to load mcrypt. By default in OSX 10.9, it actually has mcrypt-specific configuration information, but it doesn't actually activate mcrypt unless you tell it to.

The php.ini file does not, by default, exist. Instead, the file /private/etc/php.ini.default lists the default configuration, and can be used as a good template for creating the "true" php.ini, if it does not already exist.

To determine whether php.ini already exists, run:

$ ls /private/etc/php.ini 

If there is a result, it already exists, and you should skip the next command.

To create the php.ini file, run:

$ sudo cp /private/etc/php.ini.default /private/etc/php.ini 

Next, you need to add the line:

extension=mcrypt.so 

Somewhere in the file. I would recommend searching the file for ;extension=, and adding it immediately prior to the first occurrence.

Once this is done, the installation and configuration is complete. You can verify that this has worked by running:

php -m | grep mcrypt 

Which should output "mcrypt", and nothing else.

If your use of PHP relies on Apache's httpd, you will need to restart it before you will notice the changes on the web. You can do so via:

$ sudo apachectl restart 

And you're done.

Why You're Getting This Error

PHP complains if one of the files like mcrypt.so is included using the syntax extension="mcrypt.so" but the file is not in the extension_dir path ( use <?php phpinfo(); ?> or php -i to check that).

It will also tell you which php.ini config file is being loaded so you will know where the settings are coming from. Most likely it will be something like /usr/local/etc/php/5.4/php.ini if you are using the homebrew version.

Take note of the part under it that says something like "Scan this dir for additional .ini files" because what that means is it gives you a place to put your own file, like tweaks.ini that is loaded after the main configuration file so that you can make changes and keep up with them easily. Also remember that all the files in this directory get loaded in alphabetical order, so if you have one called adjustments.ini that contains mcrypt directives, and there is a mcrypt.ini, most likely your settings will be overridden.

One alternative to specifying extension="mcrypt.so" is to specify the full path to the mcrypt.so file. The other option is to edit the extension_dir setting.

What worked for me

On Mavericks I didn't have to do either. I did a fresh install of homebrew and then added the josegonzalez tap using:

brew tap josegonzalez/homebrew-php 

(My other laptop was running Mountain Lion and was also using homebrew in this setup.)

After you've tapped that awesome repo you can install php and mcrypt using something like:

brew install php54 php54-mcrypt 

What if this doesn't work (and why should I use homebrew anyway?)

I would highly advise trying this route before downloading and building it from source. It's not hard to build from source - but I don't want to have to maintain that. It's one of the reasons to use homebrew in the first place - it's a package manager (with a HUGE community).

There is a lot of development on the homebrew project and - if you have problems I'd suggest checking out their issues page

So yes you can build it from source and that might seem like a good option right now if you just want mcrypt to work but you may hate yourself for doing this later...

If you don't want to be using php54 there is also the php53 branch. They have some instructions at the repo about how to use both of them / switch between them.

If you're new to homebrew you should know that you check out what else is available using brew search php54, which gives something like:

php54 php54-lzf php54-snappy php54-amqp php54-mailparse php54-solr php54-apc php54-mcrypt php54-ssh2 php54-apcu php54-memcache php54-stats php54-boxwood php54-memcached php54-svm php54-chdb php54-midgard2 php54-tidy php54-couchbase php54-mongo php54-timezonedb php54-dbase php54-msgpack php54-tokyotyrant php54-ev php54-mysqlnd_ms php54-twig php54-gearman php54-oauth php54-uploadprogress php54-geoip php54-opcache php54-uuid php54-gmagick php54-parsekit php54-varnish php54-graphdat php54-pcntl php54-wbxml php54-http php54-pdflib php54-xcache php54-igbinary php54-phalcon php54-xdebug php54-imagick php54-proctitle php54-xhgui php54-inclued php54-pspell php54-xhp php54-intl php54-pthreads php54-xhprof php54-ioncubeloader php54-raphf php54-xmldiff php54-jsmin php54-redis php54-yac php54-judy php54-riak php54-yaf php54-leveldb php54-runkit php54-yaml php54-libevent php54-scrypt php54-yaz php54-libvirt 

TLDR

• You should use homebrew to install mcrypt if at all possible
• If you're getting errors it's probably because your configuration file(s) are messed up. Check the extension_dir path and figure out where the mcrypt.so file is and see if there is a discrepancy (or specify the full path)

For me, on Yosemite

$ brew install mcrypt php56-mcrypt 

restart computer

did the trick.

Solution with brew worked only after the following: in your php.ini

nano /private/etc/php.ini 

add this line:

extension="/usr/local/Cellar/php53-mcrypt/5.3.26/mcrypt.so" 

Warning! Set the correct PHP version.

I would recommend installing everything via homebrew if you have the option. I went in circles for a while, but installing php 5.x via brew and then the neccessary modules worked a treat. I was working with php 5.4 and used this to get going initially:

https://github.com/josegonzalez/homebrew-php

and then installed the additional modules with:

brew install php54-redis brew install php54-xdebug brew install php54-mcrypt 

...

Another possibility for those who want to keep OS X as clean as possible, is to use vagrant [1] to define a php development environment. Vagrant can use VirtualBox [2] in headless mode (~3% of CPU on my 13-inch, Mid 2009 MacBook Pro) to run a virtual machine with the webserver and php and all.

To easily create the vagrant environment you can use this great tool https://puphpet.com/

1. http://www.vagrantup.com/
2. https://www.virtualbox.org/

I'd create a shell script to install mcrypt module for PHP 5.3 without homebrew.

The scripts install php autoconf if needed and compile module for your php version.

The link is here: https://gist.github.com/lucasgameiro/8730619

Thanks

Nothing worked and finally got it working using resource @Here and Here; Just remember for OSX Mavericks (10.9) should use PHP 5.4.17 or Stable PHP 5.4.22 source to compile mcrypt. Php Source 5.4.22 here

Brew base solution worked for me

1. Install these packages

   $brew install brew install mcrypt php54-mcrypt

2. Copy default php.ini.default to php.ini

   $sudo cp /private/etc/php.ini.default /private/etc/php.ini

3. Add this line to php.ini file extension section - please verify extension path with install location in your machine

   extension="/usr/local/Cellar/php54-mcrypt/5.3.26/mcrypt.so"

4. Restart your apache server

   $apache restart

This is what I did:

$ wget http://sourceforge.net/projects/mcrypt/files/Libmcrypt/2.5.8/libmcrypt-2.5.8.tar.gz/download $ tar xzvf libmcrypt-2.5.8.tar.gz $ ./configure $ make $ sudo make install $ brew install autoconf $ wget file:///Users/rmatikolai/Downloads/php-5.4.24.tar.bz2 $ tar xjvf php-5.4.24.tar.bz2 $ cd php-5.4.24/ext/mcrypt $ phpize $ ./configure # this is the step which fails without the above dependencies $ make $ make test $ sudo make install $ sudo cp /private/etc/php.ini.default /private/etc/php.ini $ sudo vi /private/etc/php.ini 

Next, you need to add the line:

extension=mcrypt.so $ sudo apachectl restart 

mycrypt.o and mcrypt_filter.o are in the ext/.libs of your php downloaded directory. Just copy the files to ext/mcrypt, then run make && make install again.

With recent changes in brew (deprecation of homebrew/php) you now install php with mcrypt with the following.

brew install [email protected] -with-mcrypt=mcrypt 

You may have to uninstall previous installs of php

So after running brew install mcrypt php, I had to install php-mcrypt via pecl:

pecl install mcrypt-1.0.1

At the time of writing, mcrypt does not have a stable pecl release, 1.0.1 being the current release for php 7.2 and 7.3, and brew install php will install php 7.2.