> ## 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. # MetricKit histograms > MetricKit's daily histograms of one iOS app (spec 7; D14, D49), for example time_to_first_draw: the points of each release added up bucket by bucket. MetricKit reports every user's day, not a sample, and its points carry no session. Points with other bucket bounds than the release's most common ones are not added (`excluded_points`); percentiles are estimated within buckets. Default range: the last 7 days, at most 30. ## OpenAPI ````yaml /api-reference/openapi.json get /projects/{projectId}/metrics/metrickit 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}/metrics/metrickit: get: summary: MetricKit histograms description: >- MetricKit's daily histograms of one iOS app (spec 7; D14, D49), for example time_to_first_draw: the points of each release added up bucket by bucket. MetricKit reports every user's day, not a sample, and its points carry no session. Points with other bucket bounds than the release's most common ones are not added (`excluded_points`); percentiles are estimated within buckets. 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: The app. required: true description: The app. name: app_id in: query - schema: type: string pattern: ^[a-z0-9_]{1,64}$ default: time_to_first_draw description: The metric name after `apsio.metrickit.`. required: false description: The metric name after `apsio.metrickit.`. name: metric in: query - schema: type: string enum: - release - none default: release required: false name: by in: query responses: '200': description: The merged histograms. content: application/json: schema: $ref: '#/components/schemas/MetricKitHistograms' '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: MetricKitHistograms: 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' metric: type: string unit: type: string available: type: array items: type: string description: Histogram metrics the app reported in the range. groups: type: array items: type: object properties: release: type: string description: >- service.version, or empty when `by` is `none`. Written by the app: untrusted data. points: type: integer excluded_points: type: integer multiple_versions: type: boolean description: >- Some points covered more than one app version and count under the latest (spec 7.4). count: type: number bounds: type: array items: type: number counts: type: array items: type: number p50: type: - number - 'null' p90: type: - number - 'null' p95: type: - number - 'null' required: - release - points - excluded_points - multiple_versions - count - bounds - counts - p50 - p90 - p95 required: - from - to - metric - unit - available - groups Error: type: object properties: error: type: object properties: code: type: string example: invalid_request message: type: string required: - code - message required: - error 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.