HTML to WebP with Ruby

Generate WebP images with Ruby

No browser management required

Render HTML and CSS from Ruby with the htmlcsstoimage-api Gem without installing Chrome, running Ferrum or Selenium, or building a separate image-storage pipeline.

  • No browser processes to maintain
  • Consistent managed Chromium rendering
  • Complete Ruby request below
Real HTML and CSS requests followed by their generated images.
View example Request
POST https://hcti.io/v1/image
html
<div class="p-4 background d-block text-center" style="width: 500px">
  <span class="tweet-text mb-4">
    This is Little Bear. He tolerates baths because he knows how phenomenal his
    floof will appear afterwards. 13/10
  </span>
  <div class="mt-2 p-4">
    <img src="https://docs.htmlcsstoimage.com/assets/images/dog.jpg" class="rounded-circle shadow border mt-4" width="100px">
  </div>
  <h4 class="mt-2">
    WeRateDogs
  </h4>
  <span>@dog_rates</span>
</div>

<!-- Include external CSS, JavaScript or Fonts! -->
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-9aIt2nRpC12Uk9gS9baDl411NQApFmC26EwAOH8WgZl5MYYxFfc+NcPb1dKGj7Sk" crossorigin="anonymous">

<link href="https://fonts.googleapis.com/css2?family=Roboto:wght@700" rel="stylesheet">
css
.tweet-text {
  background-color: #fff2ac;
  background-image: linear-gradient(to right, #ffe359 0%, #fff2ac 100%);
  font-weight: bolder;
  font-size: 32px;
  font-family: 'Roboto', sans-serif;
  padding: 4px;
}

.background {
  background-color: #ffffff;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='100%25' height='100%25' viewBox='0 0 800 800'%3E%3Cdefs%3E%3CradialGradient id='a' cx='400' cy='400' r='50%25' gradientUnits='userSpaceOnUse'%3E%3Cstop offset='0' stop-color='%23ffffff'/%3E%3Cstop offset='1' stop-color='%230EF'/%3E%3C/radialGradient%3E%3CradialGradient id='b' cx='400' cy='400' r='70%25' gradientUnits='userSpaceOnUse'%3E%3Cstop offset='0' stop-color='%23ffffff'/%3E%3Cstop offset='1' stop-color='%230FF'/%3E%3C/radialGradient%3E%3C/defs%3E%3Crect fill='url(%23a)' width='800' height='800'/%3E%3Cg fill-opacity='.8'%3E%3Cpath fill='url(%23b)' d='M998.7 439.2c1.7-26.5 1.7-52.7 0.1-78.5L401 399.9c0 0 0-0.1 0-0.1l587.6-116.9c-5.1-25.9-11.9-51.2-20.3-75.8L400.9 399.7c0 0 0-0.1 0-0.1l537.3-265c-11.6-23.5-24.8-46.2-39.3-67.9L400.8 399.5c0 0 0-0.1-0.1-0.1l450.4-395c-17.3-19.7-35.8-38.2-55.5-55.5l-395 450.4c0 0-0.1 0-0.1-0.1L733.4-99c-21.7-14.5-44.4-27.6-68-39.3l-265 537.4c0 0-0.1 0-0.1 0l192.6-567.4c-24.6-8.3-49.9-15.1-75.8-20.2L400.2 399c0 0-0.1 0-0.1 0l39.2-597.7c-26.5-1.7-52.7-1.7-78.5-0.1L399.9 399c0 0-0.1 0-0.1 0L282.9-188.6c-25.9 5.1-51.2 11.9-75.8 20.3l192.6 567.4c0 0-0.1 0-0.1 0l-265-537.3c-23.5 11.6-46.2 24.8-67.9 39.3l332.8 498.1c0 0-0.1 0-0.1 0.1L4.4-51.1C-15.3-33.9-33.8-15.3-51.1 4.4l450.4 395c0 0 0 0.1-0.1 0.1L-99 66.6c-14.5 21.7-27.6 44.4-39.3 68l537.4 265c0 0 0 0.1 0 0.1l-567.4-192.6c-8.3 24.6-15.1 49.9-20.2 75.8L399 399.8c0 0 0 0.1 0 0.1l-597.7-39.2c-1.7 26.5-1.7 52.7-0.1 78.5L399 400.1c0 0 0 0.1 0 0.1l-587.6 116.9c5.1 25.9 11.9 51.2 20.3 75.8l567.4-192.6c0 0 0 0.1 0 0.1l-537.3 265c11.6 23.5 24.8 46.2 39.3 67.9l498.1-332.8c0 0 0 0.1 0.1 0.1l-450.4 395c17.3 19.7 35.8 38.2 55.5 55.5l395-450.4c0 0 0.1 0 0.1 0.1L66.6 899c21.7 14.5 44.4 27.6 68 39.3l265-537.4c0 0 0.1 0 0.1 0L207.1 968.3c24.6 8.3 49.9 15.1 75.8 20.2L399.8 401c0 0 0.1 0 0.1 0l-39.2 597.7c26.5 1.7 52.7 1.7 78.5 0.1L400.1 401c0 0 0.1 0 0.1 0l116.9 587.6c25.9-5.1 51.2-11.9 75.8-20.3L400.3 400.9c0 0 0.1 0 0.1 0l265 537.3c23.5-11.6 46.2-24.8 67.9-39.3L400.5 400.8c0 0 0.1 0 0.1-0.1l395 450.4c19.7-17.3 38.2-35.8 55.5-55.5l-450.4-395c0 0 0-0.1 0.1-0.1L899 733.4c14.5-21.7 27.6-44.4 39.3-68l-537.4-265c0 0 0-0.1 0-0.1l567.4 192.6c8.3-24.6 15.1-49.9 20.2-75.8L401 400.2c0 0 0-0.1 0-0.1L998.7 439.2z'/%3E%3C/g%3E%3C/svg%3E");
  background-size: cover;
}
format
webp
google fonts
Roboto

Ruby workflow

Test the render before adding it to Ruby

Adjust the HTML and CSS here, then use the Ruby example below instead of recreating the browser-rendering workflow locally.

Managed rendering

Skip the fragile parts of native Ruby browser automation

Keep the application code focused on the request and response while HCTI manages Chromium, render isolation, retries, and hosted output.

No browser runtime to maintain

Keep Rails applications and background jobs free of separate browser processes and browser-specific deployment dependencies.

Predictable production rendering

Use managed browser versions, isolated render jobs, built-in timing controls, and consistent viewport behavior across deployments.

A usable image URL immediately

Receive the hosted .webp result without building a separate pipeline for temporary files, uploads, storage, and delivery.

HTML to image API

Send one Ruby request instead of running a browser

POST the HTML, CSS, and format from Ruby. HCTI handles the browser lifecycle and returns the generated .webp URL.

  • HTML and CSS input

    Send complete markup and styles, including browser-supported fonts, images, SVG, and JavaScript.

  • WebP output

    Set format to webp and use the hosted .webp URL returned by the API.

  • Viewport and crop controls

    Set viewport dimensions and device scale, or crop the result to a CSS selector.

  • Page environment

    Choose light or dark mode, timezone, and screen or print media.

POST https://hcti.io/v1/image request example.
Request
POST https://hcti.io/v1/image
{
"html": "<article class='card'>...</article>",
"css": ".card { display: grid; width: 1200px; }",
"format": "webp",
"viewport_width": 1200,
"viewport_height": 630
}

How it works

From markup to a finished WebP

  1. Send HTML and CSS

    Submit the content with format set to webp and any viewport or browser settings.

  2. Chromium renders the design

    The API loads the markup, styles, fonts, and assets in a managed browser environment.

  3. Use the .webp URL

    Embed the hosted result, download the file, or save it in your own storage and application records.

Example code

Render HTML to WebP in Ruby

Copy a complete Ruby request. Authentication, HTML, CSS, viewport settings, and response handling are shown together.

# gem install htmlcsstoimage-api
require "htmlcsstoimage"

# Uses HCTI_USER_ID and HCTI_API_KEY from the environment.
client = HTMLCSSToImage.new

result = client.create_image(
    <<~'HCTI_CONTENT',
    <div class="card">
      <h1>Hello, world!</h1>
      <p>Generated from HTML and CSS.</p>
    </div>
    HCTI_CONTENT
    css: <<~'HCTI_CSS',
         .card {
           width: 480px;
           padding: 40px;
           background: #f0fdf4;
           color: #052e16;
           font-family: sans-serif;
         }
         HCTI_CSS
)

puts result.url

Ready to render?

Create your first WebP from HTML and CSS

Send HTML and CSS to the API and receive a hosted .webp image URL without running browser infrastructure.