HTML – Sign in with Email/Phone

Easily add email and phone number verification using Cotter's SDK. Send a magic link to your users via email, SMS or WhatsApp in just a few lines of code.

Cotter's Magic Link authenticates your user using a link. It allows seamless, fast, and secure way for your user to login to your Web App. Follow this simple guide to see how it works!

Step 0: Get the template code

To follow this guide, let's use our Hello World Template in CodeSandbox!

Step 1: Import Cotter as a dependency

Copy the following script to the head section of your HTML page

<!-- 1️⃣ Get Cotter SDK -->


Step 2: Setup a div with id cotter-form-container element to contain cotter's form

<!-- 2️⃣ Setup a div to contain the form -->
<div id="cotter-form-container" style="width: 300px; height: 300px;"></div>

Please note that id has to be cotter-form-container for the form to show up.

Step 3: Initialize Cotter

You need your API_KEY_ID for this step. Create a developer account and create a Project to get your API keys. The API Keys will only be shown once!

Grab your API_KEY_ID from the dashboard, then replace <YOUR_API_KEY_ID> with your API_KEY_ID.

<!-- 3️⃣ Show the form -->
  var cotter = new Cotter("<YOUR_API_KEY_ID>"); // 👈 Specify your API KEY ID here

    .withFormID("form_default") // Use customization for form "form_default"
    .signInWithLink() // use .signInWithOTP() to send an OTP
    .showEmailForm()  // use .showPhoneForm() to send magic link to a phone number 
    .then(payload => {
    // Read what Cotter Returns
    var respDiv = document.getElementById("user-response");
    respDiv.innerHTML = `<pre>${JSON.stringify(payload, null, 4)}</pre>`;

🎉 You're done! Now that you know how it works on the client side, let's check out how to process Cotter's payload in your backend so you can start registering and logging in users in your backend server.

Here's a fully working example of the guide we went over.

To send code/link via SMS or WhatsApp, you'll need to add some balance to you project in the Dashboard.

👉 What's Next?

Customize the Form

You can customize the form from the Dashboard > Branding. You can also add Custom CSS.

Add Additional Fields

Add Additional Fields like Name, Address, etc to the login form.

Register User to your Backend

When the user successfully authenticated, send Cotter's response to your backend to either create a new user or log the user in. Learn how to send Cotter's response and verify it in your backend:

Backend: Handling Response

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