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Overview

Image illustrating code in-app code beside a rendered in-app

OneSignal offers two in-app message editing experiences: a Drag and Drop GUI and the more advanced HTML Editor. The HTML Editor enables complete control over the appearance, behavior, and responsiveness of full-screen in-app messages.

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What you can do with the HTML Editor:

  • Layouts: Create complex layouts including side-by-side buttons.
  • Media: Embed videos, animations, slides, and more.
  • Responsiveness: Optimize for portrait, landscape, and multiple device sizes.
  • Forms: Embed forms directly into your in-apps.
  • Fonts: Use custom fonts to match your brand.
The HTML Editor is ideal for developers fluent in HTML, CSS, and JavaScript. For non-technical users, we recommend the drag-and-drop editor.

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Getting started

To enable the full-screen in-app experience, upgrade your SDK to the following versions:
  • iOS: 3.9.0+
  • Android: 4.6.3+
    • If your app uses an older SDK, in-app messages will render in a Center Modal layout instead.
Tips:

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Create a new in-app message

Go to Messages > New In-App to create, edit, test, pause, duplicate, or delete your in-app messages.

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Use the HTML Editor

Enter your HTML code on the left-hand side and preview it live. Use Send Test In-App to test responsiveness and design.

Image showing the HTML Editor beside the preview

Find HTML templates in our GitHub repo.

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Key features

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Click support

With the In-App JS Library, you can track interactions and trigger in-app behaviors.
  1. Track elements using data-onesignal-unique-label:
<button class="tag-user" data-onesignal-unique-label="my-tag-user-button">Tag User</button>
  1. Bind click actions with JavaScript:
document.querySelector(".tag-user").onclick = (e) => {
  OneSignalIamApi.tagUser(e, { fiz: "baz" });
};
Learn more in the In-App JS Library documentation.

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Asset support

You can load images, videos, fonts, and other assets in your in-apps. Assets are fetched at render time. Example: 
<img src="https://media.onesignal.com/iam/default_image_20200320.png" />

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Tag substitution (personalization)

Dynamically insert user data with tag substitution. For example: 
<div>Hi there {{ name | default: 'you' }}!</div>

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Supported contexts:

  • Text inside elements like div, p, li
  • Inside <style> blocks
  • href, src, action, and data attributes

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Not supported in:

  • <script> tags
  • Nested content structures, e.g.:
<div>
  Hi {{name}}
  <span>Here's your coupon!</span>
</div>

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Best practices

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Design responsively

Use CSS media queries to adapt layouts to various screen sizes. 
@media only screen and (max-width: 620px) {
  .btn-primary {
    width: 100% !important;
  }
}

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Test across devices

Send test messages frequently to confirm behavior and layout across device types.

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Use alt tags for accessibility

Add alt text to images for screen reader compatibility.

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Format HTML accessibly

Name and format elements clearly to support accessibility tools like screen readers.

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Account for safe areas (notches)

Modern devices have safe areas (like notches or home bars). Use safe-area-inset-* variables to pad your layout: 
body {
  padding-top: var(--safe-area-inset-top);
  padding-right: var(--safe-area-inset-right);
  padding-bottom: calc(var(--safe-area-inset-bottom) + 20px);
  padding-left: var(--safe-area-inset-left);
  margin: 0;
}

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Optimize images for mobile

Reduce file sizes and use proper resolution:
*OneSignal has no affiliation with imagekit.io, though it’s a helpful tool for optimization.

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Sample in-app HTML

We provide a default in-app template when loading the HTML Editor. It includes common methods from our JS Library. 
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>Onesignal In-App Message</title>
    <style>
      body {
        margin: 0;
        padding-top: var(--safe-area-inset-top);
        padding-right: var(--safe-area-inset-right);
        padding-bottom: calc(var(--safe-area-inset-bottom) + 20px);
        padding-left: var(--safe-area-inset-left);
        font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
        display: flex;
        align-items: center;
      }
      .center-modal {
        position: relative;
        background: #fff;
        margin: 18px;
        padding: 24px;
        border-radius: 8px;
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        height: 85%;
        width: 100%;
        box-shadow: rgb(0 0 0 / 30%) 0px 0px 12.5px, rgb(0 0 0 / 15%) 0px 0px 2.5px;
      }
      .center-modal .close-button {
        position: absolute;
        top: 0;
        right: 0;
        background: rgba(0, 0, 0, 0);
        border: none;
        z-index: 1;
        display: flex;
        justify-content: center;
        flex-direction: column;
        align-items: center;
        min-width: 48px;
        min-height: 48px;
      }
      .center-modal img {
        width: 100%;
        height: 100%;
        margin-bottom: 12px;
        object-fit: contain;
      }
      .center-modal h1 {
        margin: 0 0 12px;
        color: #222;
        font-size: 24px;
        text-align: center;
      }
      .center-modal button {
        font-size: 16px;
        color: #fff;
        background-color: #1f8feb;
        width: 100%;
        padding: 12px;
        border-radius: 4px;
        border: none;
        margin-bottom: 12px;
      }
      .button-container {
        display: flex;
        flex-direction: column;
      }
      @media screen and (min-width: 480px) {
        .button-container {
          flex-direction: row;
          gap: 12px;
          width: 100%;
        }
        .button-column {
          width: 50%;
        }
        .center-modal {
          height: 80%;
        }
      }
    </style>
  </head>
  <body>
    <div class="center-modal">
      <div class="close-button" data-onesignal-unique-label="close-button">
        <svg width="10" height="10" viewBox="0 0 8 8" fill="none">
          <path d="M7.803 1.148a.5.5 0 0 0-.707-.707L4 3.05 1.148.44a.5.5 0 0 0-.707.707L3.05 4 .44 6.852a.5.5 0 1 0 .707.707L4 4.95l2.852 2.61a.5.5 0 1 0 .707-.707L4.951 4 7.803 1.148Z" fill="#111" />
        </svg>
      </div>
      <h1>Heading</h1>
      <img src="https://media.onesignal.com/iam/default_image_20200320.png" />
      <div class="button-container">
        <div class="button-column">
          <button class="tag-user" data-onesignal-unique-label="my-tag-user-button">Tag User</button>
          <button class="push-prompt" data-onesignal-unique-label="my-push-prompt-button">Prompt Push</button>
          <button class="location-prompt" data-onesignal-unique-label="my-location-prompt-button">Prompt Location</button>
        </div>
        <div class="button-column">
          <button class="add-click-name" data-onesignal-unique-label="my-add-click-name-button">Add Click Name</button>
          <button class="send-outcome" data-onesignal-unique-label="my-send-outcome-button">Send Outcome</button>
        </div>
      </div>
    </div>
    <script>
      document.querySelector(".close-button").onclick = (e) => {
        OneSignalIamApi.close(e);
      };
      document.querySelector(".tag-user").onclick = (e) => {
        OneSignalIamApi.tagUser(e, { fiz: "baz" });
      };
      document.querySelector(".push-prompt").onclick = (e) => {
        OneSignalIamApi.triggerPushPrompt(e);
      };
      document.querySelector(".location-prompt").onclick = (e) => {
        OneSignalIamApi.triggerLocationPrompt(e);
      };
      document.querySelector(".add-click-name").onclick = (e) => {
        OneSignalIamApi.addClickName(e, "test_click_name");
      };
      document.querySelector(".send-outcome").onclick = (e) => {
        OneSignalIamApi.sendOutcome(e, "test_outcome");
      };
    </script>
  </body>
</html>

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FAQ