# Apps and sites

URL: /products/platform/apps-and-sites · Id: `capability:apps-and-sites`

> Apps and sites host every Site and App at the edge, with a preview for each Change and a one-step rollback.

Apps and sites host every [Site](/business/nouns/site) and [App](/business/nouns/app) at the edge, with a preview for each [Change](/business/nouns/change) and a one-step rollback. Both render records from [db.sb](/code/platform/db-sb), so every screen agrees with the API.

## Contract
A Site is public: its [Pages](/business/nouns/page), navigation and [Brand](/business/nouns/brand) on one or more [Domains](/business/nouns/domain). An App sits behind sign-in and shows a [Product](/business/nouns/product)'s [Nouns](/business/nouns/noun) as lists and records, and its [Verbs](/business/nouns/verb) as buttons and forms. A Page is data: its type picks a [Template](/business/nouns/template), which fills from the graph.

| Guarantee | Detail |
| --- | --- |
| Preview | Every Change renders at its own address against `test` data before it merges |
| Deploy | [Deploy](/business/nouns/version/deploy) moves `live` to a [Version](/business/nouns/version) in one step |
| Rollback | Deploying the previous Version; records are untouched |
| Rendering | Server-rendered at the edge, with Markdown for every Page and `llms.txt` for [Agents](/business/nouns/agent) |
| [Speed](/code/builders/site/design-system#the-quality-gate) | At p75, the largest element paints within 1.5 s, layout shift stays under 0.05 and input responds within 150 ms, checked on every Change |
| [Variants](/business/nouns/variant) | A [Flag](/business/nouns/flag) picks a Page's variant before render, so no visitor sees a flash |
| [Certificates](/products/platform/certificates) | Issued and renewed on every serving Domain; a failed renewal marks the Domain `degraded` and names the fix |
| [Guards](/business/nouns/guard) | Run on every publish |

[SiteBuilder](/code/builders/site) authors the Sites; this capability serves them.

## Verbs
| Verb | Object | Event |
| --- | --- | --- |
| [Version.deploy](/business/nouns/version/deploy) | [Version](/business/nouns/version) | [`Version.deployed`](/business/events/Version.deployed) |
| [Site.publish](/business/nouns/site/publish) | [Site](/business/nouns/site) | [`Site.published`](/business/events/Site.published) |
| [App.publish](/business/nouns/app/publish) | [App](/business/nouns/app) | [`App.published`](/business/events/App.published) |

## Interfaces
- [API](/code/api/reference)
- [SDK](/code/sdk/reference)
- [CLI](/code/cli/reference)
- [MCP](/code/mcp/reference)

## Example
`gridmarket.co` sells spreadsheet templates. An Agent drafts a new pricing Page as a Change, reviews it at the preview address and deploys it. Checkout conversion falls by a third, so the Agent deploys the previous Version, and the old Page is back in one step.