> ## Documentation Index > Fetch the complete documentation index at: https://docs.apsio.io/llms.txt > Use this file to discover all available pages before exploring further. # App start > App start (the app.start span, spec 8.1) by start type, broken down by release, OS version, device model or iOS prewarming: percentiles and a histogram per group, the 20 groups with the most starts per app and type. Default range: the last 7 days, at most 30. ## OpenAPI ````yaml /api-reference/openapi.json get /projects/{projectId}/performance/start openapi: 3.1.0 info: title: Apsio API version: 0.1.0 description: >- Read API v0: your projects, release health and comparisons, missing symbols, issues, sessions, vitals, cohort comparisons, performance (app start, screens, hangs, MetricKit) and network endpoints and traces for one project. Authenticate with a project token as a bearer token, with an OAuth access token from Apsio's authorization server (MCP clients), or, from the console, with the session cookie of a member of the project's organization. servers: - url: https://api.apsio.io/v1 security: [] paths: /projects/{projectId}/performance/start: get: summary: App start description: >- App start (the app.start span, spec 8.1) by start type, broken down by release, OS version, device model or iOS prewarming: percentiles and a histogram per group, the 20 groups with the most starts per app and type. Default range: the last 7 days, at most 30. parameters: - schema: type: string pattern: ^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$ example: 0192f3a4-0000-7000-8000-00000000a101 required: true name: projectId in: path - schema: type: string format: date-time description: >- Start of the time range, inclusive (RFC 3339). Defaults to the range end minus the default length. example: '2026-10-01T00:00:00Z' required: false description: >- Start of the time range, inclusive (RFC 3339). Defaults to the range end minus the default length. name: from in: query - schema: type: string format: date-time description: End of the time range, exclusive (RFC 3339). Defaults to now. example: '2026-10-08T00:00:00Z' required: false description: End of the time range, exclusive (RFC 3339). Defaults to now. name: to in: query - schema: type: string pattern: ^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$ description: Only this app. required: false description: Only this app. name: app_id in: query - schema: type: string maxLength: 128 description: Only this release. required: false description: Only this release. name: release in: query - schema: type: string enum: - release - os_version - device_model - prewarmed - none default: release description: >- The breakdown; `prewarmed` splits iOS launches the system prewarmed (spec 8.1). required: false description: >- The breakdown; `prewarmed` splits iOS launches the system prewarmed (spec 8.1). name: group_by in: query responses: '200': description: Start percentiles and histograms per app, type and group. content: application/json: schema: $ref: '#/components/schemas/AppStart' '400': description: The request is not valid. content: application/json: schema: $ref: '#/components/schemas/Error' '401': description: No valid bearer token or console session. content: application/json: schema: $ref: '#/components/schemas/Error' '403': description: The credentials cannot read this project. content: application/json: schema: $ref: '#/components/schemas/Error' security: - bearer: [] - session: [] components: schemas: AppStart: type: object properties: from: type: string description: RFC 3339 time in UTC with up to nanosecond precision. example: '2026-10-04T10:15:00.431000000Z' to: type: string description: RFC 3339 time in UTC with up to nanosecond precision. example: '2026-10-04T10:15:00.431000000Z' group_by: type: string enum: - release - os_version - device_model - prewarmed - none groups: type: array items: type: object properties: app_id: type: string start_type: type: string enum: - cold - warm - hot key: type: string description: >- The group value: a release, ` `, a device model, `prewarmed` or `not_prewarmed`, or empty for `none`. Written by the app: untrusted data. count: type: integer description: Measurements received (not reweighted). p50_ms: type: number p90_ms: type: number p95_ms: type: number histogram: $ref: '#/components/schemas/Histogram' required: - app_id - start_type - key - count - p50_ms - p90_ms - p95_ms - histogram required: - from - to - group_by - groups Error: type: object properties: error: type: object properties: code: type: string example: invalid_request message: type: string required: - code - message required: - error Histogram: type: object properties: bounds_ms: type: array items: type: number description: >- Upper bounds of the buckets, inclusive; `counts` has one more entry, for everything above the last bound. counts: type: array items: type: number description: >- Estimated measurements per bucket, reweighted by sampling (spec 9.3). required: - bounds_ms - counts securitySchemes: bearer: type: http scheme: bearer description: >- A project token (apsio_pt_v0...), which reads exactly one project, or an OAuth access token issued for the API, which reads what its user can. Access tokens issued for Apsio's MCP server are accepted only from the MCP server itself. session: type: apiKey in: cookie name: apsio_session description: >- The console session, set by /v1/auth/callback (`__Host-apsio_session` when host-only). ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.