What Is the “url” Source Type for Claude Plugins? A Deep Dive into the Manifest Schema

The url source type tells Claude to download plugin files from a public HTTP(S) endpoint rather than cloning a Git repository or reading a local path.

In the anthropics/claude-plugins-community repository, the url source type is declared in .claude-plugin/marketplace.json and individual plugin manifests when a plugin's assets are hosted externally. This mechanism allows plugin authors to distribute pre-built bundles, versioned releases, or dynamic endpoints without requiring Claude to manage Git operations.

---

Where the url Source Type Is Defined

The authoritative definition lives in .claude-plugin/marketplace.json. This JSON file serves as the central registry, mapping plugin names to their source locations and loading mechanisms.

Each plugin entry contains a source object with a mandatory source property. When this property equals "url", Claude expects a companion url property pointing to a downloadable resource.

---

Anatomy of a url Source Declaration

A minimal url-sourced plugin entry follows this structure:

{
  "source": {
    "source": "url",
    "url": "https://example.com/plugins/my-plugin-v1.0.0.zip"
  }
}

Required and optional fields

Field	Required?	Description
source	Yes	Must be the literal string "url" to activate URL-based fetching.
url	Yes	Valid HTTP or HTTPS URL pointing to the plugin bundle. Can reference .zip, .tar.gz, or a directory index.
headers	No	Key-value object for custom HTTP headers (e.g., authentication tokens).
sha256	No	Hash for integrity verification; Claude refuses to load mismatched downloads.

---

How Claude Processes the url Source Type

When resolving a plugin with source: "url", Claude performs these operations:

1. HTTP GET request – Fetches the resource at the specified url.
2. Content-type detection – Inspects headers and file extension to determine archive format.
3. Extraction – Unpacks the archive into a temporary plugin workspace.
4. Manifest validation – Locates .claude-plugin/plugin.json within the extracted contents and validates against the schema.
5. Skill registration – Loads defined skills into the active Claude session.

This flow mirrors the git-subdir source type for steps 4–5 but replaces the Git clone with a direct download, reducing dependency on external version control systems.

---

Real Examples from the Repository

Multiple plugins in anthropics/claude-plugins-community demonstrate the url source type in production use. The repository structure shows .claude-plugin/plugin.json files in several plugin directories, including:

• tres-finance-plugin/.claude-plugin/plugin.json – Financial data plugin fetching from a remote endpoint.
• testdino/.claude-plugin/plugin.json – Test utility plugin with URL-sourced assets.
• quickdesign/.claude-plugin/plugin.json – Design automation plugin.
• eli5/.claude-plugin/plugin.json – Explanation generation plugin.

These manifests confirm that url is a first-class source type alongside alternatives like git-subdir or local.

---

URL Source Type vs. Alternative Source Types

Source Type	Use Case	Trade-off
url	Static or dynamic HTTP-hosted bundles; release artifacts; CDN distributions.	Simple deployment, no Git dependency; requires manual version bumps in URL.
git-subdir	Source control integration; shared mono-repos; development workflows.	Automatic branch/tag resolution; requires Git authentication and clone time.
local	Built-in plugins; repository-bundled tools; testing scenarios.	Zero network latency; tied to specific repository checkout.

Choose url when distributing stable, versioned releases to a broad audience without requiring users to configure Git credentials.

---

Security and Integrity Considerations

The url source type introduces network attack surfaces that local and git-subdir avoid. The manifest schema mitigates this through:

• HTTPS enforcement – Plain HTTP URLs trigger warnings or blocks depending on Claude's security configuration.
• Optional sha256 verification – Plugin authors can pin expected hashes; Claude compares computed against declared before execution.
• Response size limits – Prevents abuse via unbounded downloads.

Example with integrity protection:

{
  "source": {
    "source": "url",
    "url": "https://cdn.example.com/plugins/secure-plugin-2.1.0.tar.gz",
    "sha256": "a3f5c8e9d2b1..."
  }
}

---

Summary

• The url source type instructs Claude to fetch plugin files via HTTP(S) rather than Git or local filesystem access.
• Declared in .claude-plugin/marketplace.json and individual plugin.json files, it requires a url property pointing to a downloadable archive.
• Processing involves fetching, extracting, validating, and registering—mirroring other source types but eliminating Git dependencies.
• Security features include HTTPS preference, optional SHA-256 verification, and size limits.
• Found in production plugins across the anthropics/claude-plugins-community repository, including tres-finance-plugin, testdino, quickdesign, and eli5.

---

Frequently Asked Questions

How does the url source type handle authentication?

Include an optional headers object in the source declaration to pass API keys, bearer tokens, or custom headers. Claude injects these into the HTTP request. For secrets that should not appear in manifest files, use environment variable references if your Claude deployment supports secret injection.

Can the url source type point to dynamic or API-generated endpoints?

Yes. The URL can reference any HTTP-accessible resource, including endpoints that generate plugin bundles on demand. Ensure the response returns consistent, cacheable archives and include sha256 verification if the payload may vary unexpectedly.

What archive formats does Claude support for url sources?

Standard formats include .zip, .tar.gz, and .tar.bz2. Claude inspects Content-Type headers and file extensions to select the appropriate extraction method. Uncompressed directory indexes are supported if the server returns proper MIME types for JSON and text files.

Is the url source type mandatory for external plugin hosting?

No. You can also use git-subdir to reference repositories you control. Choose url when you want faster downloads without Git overhead, or when distributing to users who lack Git credentials for your hosting platform.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}