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Horizon Docs

Web Skills

Horizon provides four skills for creating and managing websites. These skills let agents build complete websites from HTML/CSS/JS, update existing sites, fetch external page content, and list all sites owned by a user — all through natural conversation.

Prerequisites

Section titled “Prerequisites”

Web skills are available to all workspaces by default and do not require an external connection. Sites are hosted on Horizon’s infrastructure using Supabase storage. Agents must have the web skill category enabled in their configuration to invoke these skills.

Key concepts

Section titled “Key concepts”

Web skills share several common patterns:

  • Site ownership — every site is associated with the user who created it. Only the owning user (or their agents) can update or manage the site.
  • Storage-backed hosting — HTML, CSS, and JS files are uploaded to Supabase storage and served via a public URL. Sites are statically hosted and do not support server-side rendering.
  • SSRF protection — the Retrieve Site skill enforces strict protections against server-side request forgery, including blocking private IP ranges and internal hostnames.
  • Sanitization — retrieved HTML content is sanitized to remove potentially dangerous elements before being returned to the agent.

Available skills

Section titled “Available skills”
Create Site Web

Create a new website from HTML, CSS, and JavaScript content. Uploads files and returns a public URL.

Update Site Web

Fetch the current source code of a site or upload updated HTML, CSS, and JS files.

Retrieve Site Web

Fetch a public website's HTML content with SSRF protection and HTML sanitization.

List Sites Web

List all websites owned by the calling user with site metadata including name, URL, and creation date.

Common workflows

Section titled “Common workflows”

Agents frequently chain Web skills together. A typical workflow might look like:

  1. Retrieve Site to fetch an external page the user references as inspiration.
  2. Create Site to build a new site based on that reference.
  3. List Sites so the user can review all their sites.
  4. Update Site (fetch mode) to pull back the source code, then Update Site (update mode) to push changes.

Related: Skill Execution API | Creating Agents