WordPress Functions.php Snippet Generator

What belongs in functions.php?

Every WordPress theme can include a functions.php file that runs on every request, front end and admin. It is where themes declare features (add_theme_support()), register menus and image sizes and enqueue their CSS and JavaScript — and where site owners add small tweaks with actions and filters: removing the emoji script, disabling comments, changing the excerpt length or customising the login screen.

Copying snippets from random blog posts is risky: many are outdated (emoji styles moved to wp_enqueue_emoji_styles in WordPress 6.4), use unprefixed function names that collide with plugins, or skip escaping. This generator offers a curated library of 22 snippets that follow the WordPress Coding Standards: tabs, Yoda conditions, prefixed named functions with docblocks, escaped output and translatable strings using your text domain.

Choose Child theme functions.php for presentation-related code, or Site plugin for functionality that must survive a theme change — disabling comments, XML-RPC or author archives should not stop working when someone switches themes.

How to use the WordPress Functions.php Snippet Generator

1. Set your function prefix (e.g. your theme or company slug) and text domain, and choose whether the code is for a child theme or a site plugin.
2. Tick the snippets you need, or start from a preset such as Recommended cleanup or Brochure site. Options appear under each selected snippet.
3. Review any warnings — some snippets (SVG uploads, disabling feeds or XML-RPC) have trade-offs explained right there.
4. Copy the combined PHP or download it as functions.php / a plugin file, and test it on a staging site before deploying.

Example

Every snippet is a prefixed, documented function hooked into WordPress — for example, limiting revisions:

/**
 * Keep at most 10 revisions per post.
 *
 * Preferred alternative — add this line to wp-config.php instead:
 * define( 'WP_POST_REVISIONS', 10 );
 *
 * @return int
 */
function acme_limit_revisions() {
	return 10;
}
add_filter( 'wp_revisions_to_keep', 'acme_limit_revisions' );

functions.php or a site plugin?

Code in a theme’s functions.php only runs while that theme is active, and edits to a parent theme are lost on update — always use a child theme. A site-specific plugin is a single PHP file with a plugin header in wp-content/plugins/your-slug/; it keeps working regardless of the theme. A good rule: if the code changes how the site looks, put it in the theme; if it changes how the site works, put it in a plugin.

Notes on specific snippets

• Disable XML-RPC removes all methods, but xmlrpc.php is still executed. Block it at the server with the .htaccess generator for better performance under attack.
• Allow SVG uploads is limited to administrators and does not sanitise files. SVGs can carry JavaScript; use a sanitising plugin if anyone else uploads media.
• Limit post revisions: the WP_POST_REVISIONS constant in wp-config.php is simpler and applies before any plugin loads; the filter is for hosts where you cannot edit wp-config.php.
• Custom image sizes only apply to new uploads. Regenerate thumbnails (wp media regenerate) for existing images, and preview the resulting files with the Image Size Calculator.
• Enqueue assets uses filemtime() so browsers fetch new CSS/JS as soon as the file changes, and the WordPress 6.3+ strategy => defer argument for non-blocking scripts.