Sandbox
The Sandbox use case is CoverKit’s reference built-in for the template editor. It exercises the full mapping pipeline, live preview while editing, and every built-in settings control type. It does not register front-end hooks (no Open Graph meta tags, no thumbnail replacement, and no other public output).
Use Sandbox to validate layouts and field mappings safely. For production outputs, enable Open Graph image or Featured image instead.
When to enable it
Section titled “When to enable it”- Editor testing — check layout and mappings with live preview before turning on public outputs
- Extension development — study a complete settings schema and mapping catalog when building custom use cases
- Training — walk editors through controls without affecting the live site
When to use something else instead
Section titled “When to use something else instead”| Need | Use |
|---|---|
| Social / link preview meta tags | Open Graph image |
| WordPress featured / post thumbnails | Featured image |
| Custom front-end behavior | Custom use cases |
Recommended output
Section titled “Recommended output”| Recommended size | 300 × 300 px (square, cropped) |
| Formats | JPG and WebP are recommended |
If your template canvas is not square, output is still scaled and cropped to the recommended square. Match proportions or use Match aspect ratio in the use case panel to reduce unexpected cropping.
Settings
Section titled “Settings”Sandbox merges shared image settings, post-type controls, and use-case-specific fields so you can see every built-in control type in the editor.
| Setting | Control | Purpose |
|---|---|---|
| Format | Select | Output file format (PNG, JPG, WebP, GIF). |
| Quality | Range | JPG quality (shown when format is JPG). |
| Post types | Checkbox list | Which content types are included when resolving preview data (defaults to Post). |
| Posts list preview | Toggle | Small preview on the posts list for selected post types (when enabled). |
| Alt text | Text | Alt text for the preview image. |
| Caption | Textarea | Optional caption text where the UI supports it. |
| Show border | Toggle | Draw a border around the preview. |
| Include metadata | Checkbox | Include extra metadata in sandbox output when enabled. |
| Front page | Toggle | Allow this assignment on the front page (separate from the post type list). |
| Archives and search | Toggle | Allow this assignment on archives and search (not singular, not the front page). |
Required and recommended mappings
Section titled “Required and recommended mappings”- Required: Post title → map to a text layer.
- Recommended: Featured image, Post link, Post excerpt, Author, Site logo — map when your design uses them.
Configure mappings in the use case sidebar using Select layer. See How to configure use cases.
The Sandbox implementation also demonstrates per-use-case field formatting via the coverkit_use_case_sandbox_format_field_value filter (for example, a demo prefix on Post date when that source is mapped).
Verify
Section titled “Verify”- Enable Sandbox on the template and save.
- Map Post title (and other fields you need).
- Confirm the live preview updates while you edit mappings and settings in the CoverKit sidebar.
If the preview looks outdated after design changes, clear the template cache.