# Preview apps URL: https://docs.hanzo.ai/docs/openapi/platform/post-platform-projects-by-project-apps-by-app-preview > Puts a branch on its own URL. `POST /v1/platform/projects/{project}/apps/{app}/preview` > [Platform →](https://docs.hanzo.ai/docs/openapi/platform) · [All API references →](https://docs.hanzo.ai/docs/openapi) · [Get started →](https://docs.hanzo.ai/docs/guides) | | | | ------------- | ------------------------------------------------------------------------ | | **Address** | `https://api.hanzo.ai/v1/platform/projects/{project}/apps/{app}/preview` | | **Method** | `POST` | | **Operation** | `post_platform_projects_by_project_apps_by_app_preview` | | **Auth** | `Authorization: Bearer $HANZO_API_KEY` | Puts a branch on its own URL. It deploys an already-built `image` to a per-branch preview and answers its URL, the branch, the preview's slug and the deployment. The preview is a FIRST-CLASS application named `-` in the same project and tenant namespace, with its own default host — so it is completely isolated from production while reusing the same deploy mechanic. Re-previewing a branch converges that same target in place rather than stacking another one. It carries NO environment variables, deliberately: a preview never inherits production's secrets. It also does not build — `image` is required and must already exist, and `branch` defaults to the parent app's. A branch that does not resolve to a valid slug distinct from the parent's is 400. Requires a validated principal; 401 without one. ## Request 6 fields, body `application/json` (required). | Field | In | Type | Required | Description | | --------- | ---- | ------ | -------- | ------------------------------------------------------------------------- | | `project` | path | string | yes | Project is the project the parent application lives under, from the path. | | `app` | path | string | yes | App is the parent application's slug, from the path. | | `app` | body | string | — | App is the parent application's slug, from the path. | | `branch` | body | string | — | Branch is the branch to preview; defaults to the parent app's branch. | | `image` | body | string | — | Image is the already-built image ref to deploy. | | `project` | body | string | — | Project is the project the parent application lives under, from the path. | ## Response | Status | Body | Meaning | | --------- | -------------------- | -------- | | `202` | platform.previewView | accepted | | `default` | problem-details | refused | `202` body — 16 fields. | Field | In | Type | Always | Description | | -------------------------- | ---- | ----------------------- | ------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `app` | body | string | — | App is the preview application's own slug, `<app>-<branch>`. | | `branch` | body | string | — | Branch is the branch this preview maps. | | `deployment` | body | platform.deploymentView | — | | | `deployment.applicationId` | body | string | — | ApplicationID is the app this deployed — the app's `id`, not its slug. | | `deployment.buildId` | body | string | — | BuildID is the build record behind a git deploy, whose logs and status live at /v1/platform/builds. | | `deployment.commit` | body | string | — | Commit is the git ref this built — the commit a deploy or a push named, else the app's branch. | | `deployment.createdAt` | body | integer (int64) | — | CreatedAt is when the attempt was recorded, unix seconds. | | `deployment.id` | body | string | — | ID is the deployment's id (`dep_…`), minted when the attempt is recorded. | | `deployment.image` | body | string | — | Image is the full `repo:tag` this deployment put in the CR. | | `deployment.message` | body | string | — | Message is why this attempt is not live: the failure, or the note that a newer deployment went live before this build finished. | | `deployment.org` | body | string | — | Org is the tenant the deployment belongs to, from the validated identity. | | `deployment.source` | body | string | — | Source is which lane produced it: `git` (built from the repo) or `image` (an already-built ref deployed as-is, including promote and rollback). | | `deployment.status` | body | string | — | Status is where the attempt got to: `building` while its image is being built, `deploying` once its CR reached the cluster — which is the terminal success state, the app's own status is what turns `live` — `error` with the reason in Message, or `superseded` when a newer version went live first. | | `deployment.updatedAt` | body | integer (int64) | — | UpdatedAt is its last transition, unix seconds — so for a terminal deployment it is when it reached that state. | | `deployment.version` | body | integer (int64) | — | Version counts this app's deployments, from 1 and monotonically. | | `url` | body | string | — | URL is the preview's live HTTPS address. | Failure carries the platform error shape — see [Errors](https://docs.hanzo.ai/docs/errors). ## Examples **CLI** ```bash hanzo platform projects apps preview ``` **SDK** **.ts** ```ts import { Configuration, PlatformApi } from 'hanzoai'; const api = new PlatformApi(new Configuration({ accessToken: process.env.HANZO_API_KEY })); const { data } = await api.postPlatformProjectsByProjectAppsByAppPreview({ project: 'project', app: 'app', app: "", branch: "" }); ``` **.py** ```python from hanzoai.cloud import ApiClient, Configuration from hanzoai.cloud.api import PlatformApi client = ApiClient(Configuration(access_token=os.environ["HANZO_API_KEY"])) result = PlatformApi(client).post_platform_projects_by_project_apps_by_app_preview(project='project', app='app', app="", branch="") ``` **.go** ```go cfg := hanzoai.NewConfiguration() cfg.AddDefaultHeader("Authorization", "Bearer "+os.Getenv("HANZO_API_KEY")) client := hanzoai.NewAPIClient(cfg) resp, _, err := client.PlatformAPI.PostPlatformProjectsByProjectAppsByAppPreview(context.Background()).Execute() if err != nil { return err } ``` **.rs** ```rust use hanzo_client::apis::{configuration::Configuration, platform_api}; let mut cfg = Configuration::new(); cfg.bearer_access_token = std::env::var("HANZO_API_KEY").ok(); let result = platform_api::post_platform_projects_by_project_apps_by_app_preview(&cfg, Default::default()).await?; ``` **.java** ```java import ai.hanzo.cloud.ApiClient; import ai.hanzo.cloud.api.PlatformApi; ApiClient client = new ApiClient(); client.setBearerToken(System.getenv("HANZO_API_KEY")); var result = new PlatformApi(client).postPlatformProjectsByProjectAppsByAppPreview(); ``` **HTTP** ```bash curl -X POST https://api.hanzo.ai/v1/platform/projects//apps//preview \ -H "Authorization: Bearer $HANZO_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "app": "", "branch": "" }' ``` **MCP** MCP reaches **platform** through the `platform` tool, which names its 38 operations with its own verbs — this one among them, under a name only MCP declares. `describe` explains any of them: ```bash curl -X POST https://api.hanzo.ai/v1/mcp \ -H "Content-Type: application/json" \ -d '{ "jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": { "name": "describe", "arguments": { "op": "get_build" } } }' ``` --- [Platform API](https://docs.hanzo.ai/docs/openapi/platform) · [All Hanzo APIs](https://docs.hanzo.ai/docs/openapi) · [Interactive reference](https://docs.hanzo.ai/docs/openapi/reference)