---
canonical: 'https://htmlcsstoimage.com/features/html-to-webp/ruby-client'
title: 'Convert HTML to WebP in Ruby with the HCTI Gem | HTML/CSS to Image'
description: 'Convert HTML and CSS to WebP in Ruby with the htmlcsstoimage-api Gem. Generate a hosted .webp image URL.'
---

# Generate WebP images in Ruby with the HCTI Gem without managing Chrome

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.

## Why use the API instead of native Ruby browser automation?

- Keep Rails applications and background jobs free of separate browser processes and browser-specific deployment dependencies.
- Use managed browser versions, isolated render jobs, timing controls, and consistent viewport behavior across deployments.
- Receive a hosted .webp URL without building a separate pipeline for temporary files, uploads, storage, and delivery.

## Complete Ruby request (htmlcsstoimage-api Gem)

Use this request to render the example HTML and CSS as WebP.

```ruby
# 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

```

## When to use WebP

WebP combines modern compression with high visual quality, making it a strong default for images delivered on the web.

- **Efficient compression**: Deliver high-quality rendered images with smaller files than many traditional image formats.
- **Transparency support**: Keep transparent areas in HTML designs while benefiting from a web-focused output format.
- **Built for the modern web**: Use WebP for product UI, content feeds, responsive sites, and performance-sensitive delivery.

## API request

Send an authenticated `POST` request to `https://hcti.io/v1/image`. Include `html`, optional `css`, `format`, and any viewport or browser options required by the render.

```json
{
  "html": "\u003Carticle class=\u0027card\u0027\u003E...\u003C/article\u003E",
  "css": ".card { display: grid; width: 1200px; }",
  "format": "webp",
  "viewport_width": 1200,
  "viewport_height": 630
}
```

## Request workflow

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.

## Authentication and output handling

- Authenticate from trusted server-side code. Do not expose an API key in browser JavaScript, generated HTML, logs, or agent-visible output.
- Treat the returned URL as the generated `webp` resource. Download it, embed it, or copy it to configured storage as required by the workflow.
- Use viewport, selector, timing, and browser options when the default capture does not match the required dimensions or page state.
- If credentials are unavailable, ask the user to configure them securely before attempting an API request.

## Use through MCP

An MCP-compatible agent can connect to `https://mcp.hcti.io` with OAuth and use the connected HTML/CSS to Image account instead of handling an API key directly.

Ask the MCP tool to render the supplied HTML and CSS as WebP, or specify `format: webp` explicitly when constructing the request.

- [Read the MCP integration documentation](https://docs.htmlcsstoimage.com/integrations/mcp/)

## Related conversions

- [URL to WebP](https://htmlcsstoimage.com/features/url-to-webp/ruby-client.md): Capture a public webpage as WebP instead of supplying HTML and CSS.
- [HTML to PNG](https://htmlcsstoimage.com/features/html-to-png/ruby-client.md): PNG preserves sharp edges, text, and transparency, making it ideal for interface captures and designed graphics.
- [HTML to JPEG](https://htmlcsstoimage.com/features/html-to-jpeg/ruby-client.md): JPEG is a practical choice for photographic and content-rich images where broad compatibility and smaller files matter.
- [HTML to PDF](https://htmlcsstoimage.com/features/html-to-pdf.md): Generate paginated documents with page sizing, margins, backgrounds, and print styles.

## Reference links

- [API authentication and request documentation](https://docs.htmlcsstoimage.com/getting-started/using-the-api/)
- [MCP integration documentation](https://docs.htmlcsstoimage.com/integrations/mcp/)
- [Interactive HTML to WebP page](https://htmlcsstoimage.com/features/html-to-webp/ruby-client)
- [Plans and current limits](https://htmlcsstoimage.com/pricing.md)