Add Sumly to a WordPress site

The easiest way is a header and footer plugin such as WPCode: paste Sumly's line into its header box and it goes into the head of every page. A child theme works too.

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WordPressone line, every page

Visitors

Code Snippets › Header & Footer › Header

<script defer src="…/s.js" data-site="sl_…">

✓ Changes saved First visit/ · from Google

Drawn with an example line.

Step by step

1
In Sumly, open Visitors and copy your project's line.
2
In WordPress, install WPCode (Insert Headers and Footers) from Plugins › Add New, then open Code Snippets › Header & Footer.
3
Paste the line into Header and click Save Changes. If you use a caching plugin, clear its cache, then open your site: the visit shows on Visitors.

The whole line, as Sumly shows it with your own key.

<script defer src="https://sumly.dev/s.js" data-site="sl_your_key"></script>

Without a plugin: in your child theme's functions.php, so a theme update does not take it away.

add_action( 'wp_head', function () {
    echo '<script defer src="https://sumly.dev/s.js" data-site="sl_your_key"></script>';
} );

Or let your coding assistant do it

Paste this into Claude Code, Cursor or Codex in your project. It fits the code to how your project is built, asks you for the dashboard steps and leaves the keys to you.

See what it says

Set up WordPress for Sumly in this project.

Sumly (https://sumly.dev) shows revenue next to the visits and app users it came from. The full guide is https://sumly.dev/install/wordpress; read it if anything below is unclear.

Steps:
1. In Sumly, open Visitors and copy your project's line.
2. In WordPress, install WPCode (Insert Headers and Footers) from Plugins › Add New, then open Code Snippets › Header & Footer.
3. Paste the line into Header and click Save Changes. If you use a caching plugin, clear its cache, then open your site: the visit shows on Visitors.

Header: The whole line, as Sumly shows it with your own key.
```
<script defer src="https://sumly.dev/s.js" data-site="sl_your_key"></script>
```

Child theme: Without a plugin: in your child theme's functions.php, so a theme update does not take it away.
```
add_action( 'wp_head', function () {
    echo '<script defer src="https://sumly.dev/s.js" data-site="sl_your_key"></script>';
} );
```

Keep in mind: On WordPress.com, plugins need a paid plan (Personal or higher); then the steps are the same. If WPCode is switched off, the line stops being printed. It stays saved and comes back when you switch it on. The child theme's way works with any theme that calls `wp_head()`, which almost all do.

How to work:
- Look at how this project is built first, and fit the code to its framework and its way of doing things; the examples above are a starting point, not something to paste as is.
- Steps that happen in a dashboard (Sumly, or WordPress's own) are mine: tell me exactly what to click, then wait for me.
- Keys the code needs belong in environment variables, never in the code or the repository. Never ask me to paste a secret key into this chat; tell me which variable to set.
- Change only what this needs, show me the changes before you commit, and tell me how to check that it works.
- sl_your_key stands for the project's public key; it is on the Visitors page in Sumly. Ask me for it.

Consent

In the EU, the EEA, the UK and Switzerland the script sets no cookie until you call sumly.consent(true), usually from your cookie banner once the visitor agrees, and counts visits without one until then. To wait for consent everywhere, add data-consent="always" to the line. Or add data-cookieless: no Sumly cookie anywhere, so nothing to ask, but a returning visitor counts as new each day and a payment is only traced to a visit on the same day.

Checkout

Stripe Payment Links and buy buttons, and Gumroad product links, on your pages carry the visitor into checkout by themselves. For a WooCommerce shop, see its guide.

Your own domain

On Starter and Growth, one DNS record serves the script from your own address, past ad blockers: under Visitors › Add tracking › Your own address, enter one such as signal.your-site.com and add the CNAME it shows. If your checkout or app is on another domain, add it under Projects and payments › Other domains: the line then carries data-domains and one person stays one visitor across them.

Clicks and sections

Clicks on links to other sites count by themselves. Mark a button with data-sumly-event="signup" to count its clicks, and a section with data-sumly-scroll="pricing" to count the page views that reached it, a goal such as reached pricing.

Good to know

On WordPress.com, plugins need a paid plan (Personal or higher); then the steps are the same.
If WPCode is switched off, the line stops being printed. It stays saved and comes back when you switch it on.
The child theme's way works with any theme that calls wp_head(), which almost all do.

From WordPress's own documentation, checked 4 November 2026: wpcode.com/docs/using-the-global-header-footer-settings, developer.wordpress.org/reference/hooks/wp_head, wordpress.com/support/adding-code-to-headers .