# Registries

Learn how registries map URL schemes to template locations.

A registry maps URL schemes to template locations using pattern matching. The CLI includes a built-in registry with schemes for popular component libraries and the Croct template catalog.

## Format

A registry is a JSON5 array of objects, each with a [`pattern`](#pattern-prop) and a [`destination`](#destination-prop):

**registry.json5**

```json5
[
  {
    "pattern": "^croct://?(.+)$",
    "destination": "croct/$1"
  },
  {
    "pattern": "^shadcn-ui://?(.+)$",
    "destination": "shadcn-ui/$1"
  }
]
```

## Properties

Each entry in the registry array has the following properties:

- `pattern`: `string`

  A regular expression matched against the source URL.

  Use capture groups to extract parts of the URL for use in the destination.

- `destination`: `string`

  The resolved path for matching sources.

  Use `$1`, `$2`, etc. to reference capture groups from the pattern. Destinations are resolved relative to the registry file location.

## Built-in schemes

The built-in registry provides the following schemes:

| Scheme           | Description            |
| ---------------- | ---------------------- |
| `croct://`       | Croct templates        |
| `shadcn-ui://`   | shadcn/ui components   |
| `magic-ui://`    | Magic UI components    |
| `hero-ui://`     | Hero UI components     |
| `material-ui://` | Material UI components |
| `mantine://`     | Mantine components     |
| `tailwind://`    | Tailwind utilities     |
| `nextjs://`      | Next.js templates      |
| `npm://`         | npm packages           |

For example, `croct://starter/nextjs` matches the pattern `^croct://?(.+)$` and resolves to the path `croct/starter/nextjs` relative to the registry file.

## Resolution

Patterns are matched in order, and the first match wins. Destinations are resolved relative to the registry file location, so a registry hosted on GitHub will resolve paths to files in the same repository.

## Custom registries

To use your own registry, pass the [`--registry`](/reference/cli/global-options) global option:

```sh
croct --registry https://example.com/registry.json5 use my-scheme://template
```

This tells the CLI to load your registry file instead of the built-in one.

For details on contributing new schemes to the built-in registry, see the [publishing templates tutorial](/immersion/tutorials/template-publishing).

## Explore

- [Sources](/reference/cli/templates/sources): See the template source reference.
- [Use](/reference/cli/commands/use): Learn how to apply a template to your project.