Mixed (others) (category)

add_admin_bar_menus

Fires immediately after WordPress creates the basic admin bar items.

after_menu_locations_table

Fires after the table on the Appearance → Menus → Manage Locations admin tab, allowing HTML to be output.

comment_class

Allows you to change the list of CSS classes applied to each comment <li> tag in the template.

cron_schedules

Allows you to add a new time interval for Cron tasks (schedules).

doing_it_wrong_trigger_error

Allows you to prevent an error from being generated when _doing_it_wrong() is called.

phpmailer_init

Allows you to configure authenticated SMTP email delivery. Fires after PHPMailer{} is initialized.

pre_http_request

Allows you to short-circuit an HTTP request and return a specified value.

register_new_user

Fires after a new user is registered, allowing an action to be performed.

show_admin_bar

Allows you to show or hide the admin bar (toolbar) on the front end. The hook works only on the front end; it does not work in the admin area.

user_trailingslashit

Allows you to remove/add a trailing slash (/) to URLs processed by user_trailingslashit().

Basic (main)

after_setup_theme

Fires on every page load immediately after the theme is initialized. It is normally used to set up basic theme features; see add_theme_support().

init

Fires after WordPress has finished loading but before any HTTP headers are sent.

plugins_loaded

Fires immediately after all active plugins have loaded.

WP_Query

ajax_query_attachments_args

Allows you to change the parameters passed to WP_Query during an AJAX request for media files (attachments).

post_limits

Changes the LIMIT clause of the SQL query before posts are retrieved from the database by WP_Query.

post_search_columns

Allows you to change the list of columns searched when using the s search parameter in WP_Query.

posts_where

Allows you to change the WHERE clause of an SQL query used to retrieve posts with WP_Query.

pre_get_posts

Allows changing a WP_Query query before it runs.

request

Filters the parameters (variables) of the main WordPress query.

Posts (pages attachments)

attachment_fields_to_save

Saves a custom field added to an image (attachment) using the attachment_fields_to_edit hook.

before_delete_post

Fires before a post is deleted, at the very beginning of wp_delete_post().

delete_post

Fires before a post (of any post type) is deleted from the database.

edit_post

Fires only when an existing post is updated.

post_class

Allows you to change the list of CSS classes for the current post.

post_updated

Fires after an existing post is updated.

publish_post

Fires when a post (a post of the post type) is published or updated, allowing an action to be performed.

register_post_type_args

Allows changing the arguments passed to register_post_type when any post type is registered. It fires before the default arguments are generated, merged with the supplied arguments, and applied.

sanitize_title

Allows changing a string passed to sanitize_title() after unwanted characters have been removed.

save_post

Fires whenever a post or page is created or updated, including publication through import, XML-RPC, or email.

save_post_(post_type)

Fires whenever a post of the specified type (post, page) is created or updated, including when it is published through import, XML-RPC, or email.

the_content_feed

Filters the full description content output in a feed. The feed type is passed in the second parameter.

the_excerpt

Filters the content of the post's “Excerpt” field before it is displayed. Used in the_excerpt().

the_excerpt_rss

Called by the the_excerpt_rss() function, which outputs a short description in an RSS feed. Passes the short description text so it can be changed.

the_title

Applies to the post title, before retrieving or displaying it.

use_block_editor_for_post

Allows you to enable or disable Gutenberg (the WordPress block editor) for an individual post.

use_block_editor_for_post_type

Allows you to enable/disable content editing through Gutenberg (the WordPress block editor) for a post type.

Users

auth_cookie_expiration

Allows you to change the lifetime of cookies used to authenticate users.

author_link

Allows you to change the URL of an author's archive page.

editable_roles

Allows you to change the list of site user roles requested by get_editable_roles().

map_meta_cap

Allows changing the primitive capabilities required when checking a user's permissions.

post_types_to_delete_with_user

Allows you to change the list of post types to delete when a user is deleted. This applies only to posts created by the user.

the_author_posts_link

Allows you to change the HTML of the link to the author's post archive page.

user_contactmethods

Allows you to change a user's additional contact information.

user_has_cap

Allows you to remove or add capabilities for an individual user.

user_register

Fires immediately after a new user has been registered on the site and the user data has been added to the database.

Terms (tags categories)

created_(taxonomy)

Fires after a term (taxonomy item) is added.

edited_(taxonomy)

Fires after a term (category or other taxonomy item) has been updated and its cache cleared.

get_terms_orderby

Filters the part of the SQL query responsible for the sorting column in get_terms(), get_categories(), wp_list_categories().

pre_insert_term

Allows you to change a term name (category or tag) before it is sanitized and inserted into the database.

register_taxonomy_args

Allows you to change the arguments specified when registering a taxonomy.

single_cat_title

Allows you to change the title of a category archive page.

taxonomy_labels_(taxonomy)

Allows you to change the labels (headings) of a specified taxonomy, such as categories or tags.

term_updated_messages

Allows you to change messages displayed when terms (categories, tags, and so on) are handled on their creation and editing pages.

update_post_term_count_statuses

Allows you to change the list of post statuses included when updating taxonomy term counts.

Media-data

embed_oembed_html

Allows you to change cached oEmbed HTML when it is displayed.

getimagesize_mimes_to_exts

Allows you to add an image MIME type and its corresponding file extension.

manage_media_columns

Allows you to change the list of registered columns in the Media table.

oembed_dataparse

Allows you to change the content (HTML) generated when URLs supported by WordPress's oEmbed format are embedded. The change occurs before caching.

upload_mimes

Allows adding/removing file types that can be uploaded to the site (file MIME types allowed for upload).

Translations (i18n l10n)

gettext

Allows you to change a translated string (text).

gettext_with_context

Allows you to change translated text whose translation is requested with a translation context by the _x() function.

ngettext

Allows you to change a string translated by _n().

override_load_textdomain

Allows you to override loading the translation .mo file for a specified text domain.

Meta-data

is_protected_meta

Allows you to add the names (keys) of meta-fields that should be considered protected/hidden.