On top of the template filters that Twig comes with, Craft provides a few of its own.

# camel

Returns a string formatted in “camelCase”.

{{ "foo bar"|camel }}
{# Outputs: fooBar #}

# currency( currency, stripZeroCents )

Formats a number with a given currency according to the user’s preferred language.

If you pass true into the second argument, the “.00” will be stripped if there’s zero cents.

{{ 1000000|currency('USD') }} => $1,000,000.00
{{ 1000000|currency('USD', true) }} => $1,000,000

# datetime

Formats a date according to the user’s preferred language.

# filesize

Formats a number of bytes into something nicer.

# filter

Removes any empty elements from an array and returns the modified array.

# group

Groups the items of an array together based on common properties.

{% set allEntries = craft.entries.section('blog').find() %}
{% set allEntriesByYear = allEntries|group('postDate.year') %}

{% for year, entriesInYear in allEntriesByYear %}
    <h2>{{ year }}</h2>

        {% for entry in entriesInYear %}
            <li><a href="{{ entry.url }}">{{ entry.title }}</a></li>
        {% endfor %}
{% endfor %}

# hash

Prefixes the given string with a keyed-hash message authentication code (HMAC), for securely passing data in forms that should not be tampered with.

<input type="hidden" name="foo" value="{{ 'bar'|hash }}">

PHP scripts can validate the value via CSecurityManager::validateData():

$foo = craft()->request->getPost('foo');
$foo = craft()->security->validateData($foo);

if ($foo !== false) {
    // data is valid

# indexOf

Returns the index of a passed-in value within an array, or the position of a passed-in string within another string. (Note that the returned position is 0-indexed.) If no position can be found, -1 is returned instead.

{% set colors = ['red', 'green', 'blue'] %}
<p>Green is located at position {{ colors|indexOf('green') + 1 }}.</p>

{% set position = "team"|indexOf('i') %}
{% if position != -1 %}
    <p>There <em>is</em> an “i” in “team”! It’s at position {{ position + 1 }}.</p>
{% endif %}

# intersect

Returns an array containing only the values that are also in a passed-in array.

{% set ownedIngredients = [
    'triple sec',
    'grapefruit juice'
] %}

{% set longIslandIcedTeaIngredients = [
    'triple sec',
    'sweet and sour mix',
] %}

{% set ownedLongIslandIcedTeaIngredients =

# kebab

Returns a string formatted in “kebab-case”.

That’s a reference to shish kebabs for those of you that don’t get the analogy.

{{ "foo bar?"|kebab }}
{# Outputs: foo-bar #}

# lcfirst

Lowercases the first character of a string.

# markdown or md

Processes a string with Markdown.

{% set content %}
# Everything You Need to Know About Computer Keyboards

The only *real* computer keyboard ever made was famously
the [Apple Extended Keyboard II] [1].

{% endset %}

{{ content|markdown }}

# number

Formats a number according to the user’s preferred language.

You can optionally pass false to it if you want group symbols to be omitted (e.g. commas in English).

{{ 1000000|number }} => 1,000,000
{{ 1000000|number(false) }} => 1000000

# parseRefs

Parses a string for reference tags.

{% set content %}
    {entry:blog/hello-world:link} was my first blog post. Pretty geeky, huh?
{% endset %}

{{ content|parseRefs|raw }}

# pascal

Returns a string formatted in “PascalCase” (AKA “UpperCamelCase”).

{{ "foo bar"|pascal }}
{# Outputs: FooBar #}

# percentage

Formats a percentage according to the user’s preferred language.

# replace

Replaces parts of a string with other things.

You can replace multiple things at once by passing in an object of search/replace pairs:

{% set str = "Hello, FIRST LAST" %}

{{ str|replace({
    FIRST: currentUser.firstName,
    LAST:  currentUser.lastName
}) }}

Or you can replace one thing at a time:

{% set str = "Hello, NAME" %}

{{ str|replace('NAME', }}

You can also use a regular expression to search for matches by starting and ending the replacement string’s value with forward slashes:

{{|lower|replace('/[^\\w]+/', '-') }}

Any backslashes in the regular expression will need to be double-escaped '\\' for them to work properly.

# snake

Returns a string formatted in “snake_case”.

{{ "foo bar"|snake }}
{# Outputs: foo_bar #}

# translate or t

If the user’s preferred language doesn’t match your site’s language, Craft will look for a translation file for the user’s preferred language, and see if it contains a translation for the preceding string (see Translating Static Text).

If your text contains dynamic variables, add tokens to the string where they should go, and pass an object to the t filter that contains their values:

<p>{{ "Welcome, {name}"|t({ name: user.friendlyName }) }}<p>

# ucfirst

Capitalizes the first character of a string.

# ucwords

Capitalizes the first character of each word in a string.

# values

Returns an array of all the values in a given array, but without any custom keys.

{% set arr1 = {foo: "Foo", bar: "Bar"} %}
{% set arr2 = arr1|values %}
{# arr2 = ["Foo", "Bar"] #}

# without

Returns an array without the specified element(s).

{% set entries = craft.entries.section('articles').limit(3).find %}
{% set firstEntry = entries[0] %}
{% set remainingEntries = entries|without(firstEntry) %}