Add Sumly to a Webflow site

Webflow's head code is for the whole site. Paste Sumly's line there and publish.

Open the live demo Start free

Webflowone line, every page

Visitors

Site settings › Custom code › Head code

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

✓ Published 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 Webflow, open Site settings › Custom code and paste the line into Head code. Click Save changes.
3
Publish the site. Open the published site, not the Designer, and 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>

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 Webflow 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/webflow; read it if anything below is unclear.

Steps:
1. In Sumly, open Visitors and copy your project's line.
2. In Webflow, open Site settings › Custom code and paste the line into Head code. Click Save changes.
3. Publish the site. Open the published site, not the Designer, and the visit shows on Visitors.

Head code: 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>
```

Keep in mind: Custom code needs a paid Site plan or a paid Workspace; a free site on webflow.io cannot have it. It does not run in the Designer. To see it there, turn on **Run custom code in Preview** under Site settings › Custom code. Code in a page's own settings is for that page only. The site-wide box makes every page count.

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 Webflow'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

Webflow has no cookie banner of its own. If you add one, call sumly.consent(true) from it when the visitor agrees; until then, in the EU, the EEA, the UK and Switzerland, visits are counted without a cookie.

Checkout

Stripe Payment Links, pricing tables and buy buttons, Polar checkout links, Paddle buttons and Gumroad product links on your pages carry the visitor into checkout by themselves. For a checkout your own server creates, pass the sumly_vid cookie as metadata named sumly_visitor_id, or send the buyer back to a page with the script and ?session_id={CHECKOUT_SESSION_ID} (Stripe) or ?checkout_id={CHECKOUT_ID} (Polar).

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

Custom code needs a paid Site plan or a paid Workspace; a free site on webflow.io cannot have it.
It does not run in the Designer. To see it there, turn on Run custom code in Preview under Site settings › Custom code.
Code in a page's own settings is for that page only. The site-wide box makes every page count.

From Webflow's own documentation, checked 4 November 2026: help.webflow.com/hc/en-us/articles/33961357265299-Custom-code-in-head-and-body-tags, help.webflow.com/hc/en-us/articles/33961232582419-Choose-a-Site-plan .