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Here's How to Integrate Cotter's Magic Link to Your Webflow Site in Less Than 15 minutes!

kevinchandra profile image Kevin Chandra Originally published at on ・3 min read

In this tutorial we're going to guide you on how to authenticate your users using magic links on Webflow.

Here's How to Integrate Cotter's Magic Link to Your Webflow Site in Less Than 15 minutes!

Webflow + Cotter's Magic Link Tutorial

Part 1: Cotter Setup

Go to to create an account. Once you have created an account make sure to create a new project and grab the API Key ID. We will be using your API Key ID later in part 3.

Part 2: Webflow Setup

For this tutorial we have created 2 pages: Login Page and Protected Page. The login page will display the embedded Cotter login form for your users to type in their email while the protected page will display protected content that only a logged in user can view.

Login Page Setup (where the login form will show up)

On the login page we need to include a section element to load Cotter's login form; moreover, we need to set that section id "cotter-form-container". This enables Cotter's JS SDK to load the login form to the section element that we just added.

After finishing the page setup we can start with adding custom code to the login page. Copy paste the code below to the custom code tab on the login page settings.

  • Get Cotter JS SDK

Add the code below to the head of the Login Page.

<!--Get Cotter JS SDK-->
<script src="" 
  • Initialize Cotter

Add the code below to the body of Login Page.

<!-- 2. Initialize Cotter -->
  var cotter = new Cotter("<YOUR_API_KEY_ID>"); // 👈 Specify your API KEY ID here
    // Choose what method of login do you want
    // Sign In with Magic Link
    // Send Magic Link via email

    .then(payload => {
      // save OAuth token
      localStorage.setItem("user_session", JSON.stringify(payload));

      // redirect to the protected page
      window.location.href = "/protected";
    .catch(err => {
      // handle error

Make sure that you have pasted your API Key ID on the code block above.

Protected Page Setup (and any other page you want to protect)

Now let’s move on to the protected page, we need to include a header (h2) element and set that header id “welcome-text-heading” in order to load the user’s email address and a button element with button id “signout-button” to enable sign out functionality for the user.

Moreover, we’ll be adding custom code to both the header and the body. We’ll be adding custom code to the header to check if a user is logged in and to fetch the user’s OAuth token. The custom code in the body will be used to parse the user data and display his/her email on the page.

Add the code below to the header of the Protected Page

// 1. We check if a user has already logged in
var cotterOAuthToken = localStorage.getItem("user_session");

// 2. If user is not logged in then we redirect to the login page
if (!cotterOAuthToken || cotterOAuthToken.length <= 0) window.location.href = "/";

// 3. If user is logged in then we fetch the user data
let url = ""
fetch(url, {
    method: 'POST',
    cache: 'no-cache',
    headers: {
      'Content-Type': 'application/json'
    body: cotterOAuthToken
  .then(resp => resp.json())
  .then(data => {
    if(!data.success) { window.location.href = "/" }

Add the code below to the body of the Protected Page

// 1. Fetch the user data
let token = JSON.parse(cotterOAuthToken);
// 2. Display user email
document.getElementById("welcome-text-heading").innerHTML = `Welcome ${},`;
// 3. Display sign out button
document.getElementById("signout-button").addEventListener("click", () => {
    window.localStorage.removeItem("user_session"); // Log user out
    window.location.href. "/"; // Redirect to login

Part 3: Publish and Test

We've arrived at the last part of this tutorial and all that you need to do is to click publish and test Cotter's magic link authentication for your Webflow website!

Questions & Feedback

Come and talk to the founders of Cotter and other developers who are using Cotter on Cotter's Slack Channel.

Ready to use Cotter?

If you enjoyed this tutorial and want to integrate Cotter into your website or app, you can create a free account and check out our documentation.

If you need help, ping us on our Slack channel or email us at

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