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Filters

Custom and built-in Twig filters available inside FeedOtter email templates. All tokens use [[ ]] for output and [% %] for logic blocks.

Basic syntax:

[[ variable | filterName ]]
[[ variable | filterName(arg1, arg2) ]]
[[ variable | filterName(anotherVariable) ]]

Working with Dates

FeedOtter can use any date format supported by PHP. Full reference: https://php.net/manual/en/datetime.formats.date.php

The most common date variable is feedotter.send_date_object, which represents the scheduled send date of the campaign.

[[feedotter.send_date_object | date('F j, Y')]]       // September 21, 2022
[[feedotter.send_date_object | date('F d')]]           // September 21
[[feedotter.send_date_object | date('M. j, Y')]]       // Sep. 21, 2022
[[feedotter.send_date_object | date('d-m-y')]]         // 21-09-22
[[feedotter.send_date_object | date('l, F j, Y')]]     // Wednesday, September 21, 2022
[[feedotter.send_date_object | date('D, F j, Y')]]     // Wed, Sep. 21, 2022
[[feedotter.send_date_object | date('F Y')]]           // September 2022
[[feedotter.send_date_object | date('n/j/Y')]]         // 9/21/2022

To render the date in a specific timezone, pass the timezone as a second argument to date():

[[feedotter.send_date_object | date('g:i A T', 'America/Los_Angeles')]]  // 9:00 AM PDT
[[feedotter.send_date_object | date('F j, Y', 'America/Chicago')]]       // September 21, 2022

You can also convert the timezone first using switch_timezone and then format:

Custom Filters

linkColor

Finds all <a> tags in an HTML string and injects an inline color style, overriding any existing color declaration. Passes through plain text (no HTML) unchanged.

Argument
Type
Description

color

string

Hex color value. Accepts #RRGGBB, RRGGBB, #RGB, or RGB.

Output on each anchor: style="color: #c0392b !important;"

If the <a> tag already has a style attribute, the new color is appended and any prior color declaration is removed.

resize

Rewrites an image URL to pass through the FeedOtter resize proxy at the specified dimensions.

Argument
Type
Required
Description

width

int

Yes

Target width in pixels.

height

int

No

Target height in pixels.

overlay

string

No

Overlay identifier passed to the resize service.

cleanImages

Strips width and height attributes (both HTML attributes and inline style values) from all <img> tags, then adds width="100%" to any image that has no width set. Useful when displaying raw HTML content in an email.

Common use case — rendering raw CMS HTML:

regex_replace

Runs a PHP preg_replace on a string. Gives full control over substitution using regular expressions.

Argument
Type
Required
Description

pattern

string

Yes

A PCRE regex pattern (including delimiters, e.g. /foo/i).

replacement

string

Yes

Replacement string (supports backreferences like $1).

limit

int

No

Max replacements. Default -1 (all).

Common use case — strip Yoast/plugin-inserted footer text:

intl_date

Formats a DateTime object using the ICU pattern format via PHP's IntlDateFormatter. Useful for localized date strings.

Argument
Type
Default
Description

locale

string

es_ES

A BCP 47 locale string (e.g. en_US, fr_FR).

pattern

string

EEEE d, 'de' MMMM 'de' yyyy

ICU date pattern.

switch_timezone

Converts a DateTime object to a different timezone and returns the adjusted DateTime. Typically chained before a date format filter.

Argument
Type
Description

timezone

string

A valid PHP timezone identifier (e.g. America/Chicago).

splitsentences

Splits a block of text into an array of individual sentences. Sentences shorter than 4 characters are discarded. Typically used with a [% for %] loop.

shuffle

Randomly shuffles an array of posts or items. Each render produces a different order.

marker

Tags an array of posts with a named marker (recording their URLs internally) and returns the array unchanged. Used by FeedOtter for deduplication tracking.

Argument
Type
Description

markerName

string

An arbitrary label for this group of posts.

kebab

Converts a string to lowercase kebab-case, stripping non-alphanumeric characters and replacing spaces with hyphens.

Commonly Used Built-in Filters

These standard Twig filters are also available in FeedOtter templates.

Filter
Description
Example

date(format)

Format a date/DateTime.

[[ feedotter.send_date_object | date('F Y') ]]

truncate(length, preserve, separator)

Truncate plain text.

[[ post.post_excerpt_text | truncate(200, true, '...') ]]

upper

Uppercase a string.

[[ post.post_title | upper ]]

lower

Lowercase a string.

[[ post.post_title | lower ]]

capitalize

Capitalize the first character.

[[ post.post_title | capitalize ]]

title

Title-case every word.

[[ post.post_title | title ]]

trim

Strip leading/trailing whitespace.

[[ custom.field | trim ]]

nl2br

Convert newlines to <br> tags.

[[ custom.bio | nl2br ]]

replace({'old':'new'})

Find-and-replace within a string.

[[ post.post_title | replace({'&amp;': 'and'}) ]]

default(fallback)

Return a fallback if the value is empty.

[[ custom.headline | default('Read More') ]]

length

Count characters in a string or items in an array.

[% if post.post_title | length > 60 %]

slice(start, length)

Return a portion of a string or array.

[[ posts | slice(0, 3) ]]

join(glue)

Join an array into a string.

[[ tags | join(', ') ]]

first

First item of an array.

[[ posts | first ]]

last

Last item of an array.

[[ posts | last ]]

reverse

Reverse a string or array.

[[ posts | reverse ]]

sort

Sort an array.

[[ tags | sort ]]

url_encode

URL-encode a string.

[[ post.post_url | url_encode ]]

json_encode

Encode a value as JSON.

[[ data | json_encode ]]

striptags

Strips HTML tags from a string. When called with no argument, all tags are removed. Pass an allowlist of tags to keep specific ones — useful when you need to render CMS HTML in email without carrying over layout-heavy or unknown markup.

Note: Even with an allowlist, CMS content can still carry unsafe style attributes or deeply nested structures. Pair with cleanImages and regex_replace to further sanitize.

Full cleanup chain for CMS HTML content:

Rarely Used / Specialist Filters

These filters are available but not commonly needed in standard templates.

truncate_html

Truncates an HTML string to approximately length plain-text characters, preferring a sentence boundary, then a word boundary. Automatically closes any tags left open by the cut.

Argument
Type
Default
Description

length

int

100

Maximum number of plain-text characters.

truncate_sentence

Truncates a plain-text string to length characters, snapping back to the nearest sentence-ending punctuation (., ?, or !) so the result never ends mid-sentence.

Argument
Type
Description

length

int

Maximum character count before snapping to a sentence boundary.

resize2

Alternative resize filter backed by Cloudinary. Resizes to the given width (and optional height) using a fill crop. Returns a Cloudinary fetch URL.

Argument
Type
Required
Description

width

int

Yes

Target width in pixels.

height

int

No

Target height in pixels.

mktohash

Generates a random alphanumeric string of a given length. Useful for Marketo hash tokens or unique identifiers.

Argument
Type
Default
Description

length

int

12

Number of characters to generate.

foDebugJson

Pretty-prints any value (object, array, or scalar) as an HTML-escaped JSON string. Intended for template debugging only — remove before sending.

Last updated: August 2026

Last updated