> ## Documentation Index > Fetch the complete documentation index at: https://api-docs.hrizn.io/llms.txt > Use this file to discover all available pages before exploring further. # Create vehicle comparison > Creates a vehicle comparison comparing 2-5 vehicles side-by-side. The comparison is generated asynchronously. Use the returned `id` with `GET /content/{id}` to check status and retrieve the result. ## OpenAPI ````yaml /openapi.yaml post /comparisons openapi: 3.1.0 info: title: Hrizn Public API version: 1.2.0 description: > The Hrizn Public API allows partners to programmatically create content, manage inventory descriptions, and integrate with the Hrizn platform. All endpoints are prefixed with `/public` and require an API key passed via the `X-API-Key` header (except the health check). contact: email: support@hrizn.io servers: - url: https://api.app.hrizn.io/v1/public description: Production security: - apiKeyAuth: [] tags: - name: IdeaClouds description: Create and manage AI-powered keyword research - name: Content Intelligence description: AI-powered content gap analysis and recommendations - name: Content description: Generate content from IdeaClouds - name: Compliance description: Run OEM compliance checks on content - name: Content Tools description: Generate SEO metadata, schemas, and social snippets - name: Inventory description: Access vehicle data and AI descriptions - name: Site description: View dealership details and configuration - name: Webhooks description: Manage webhook subscriptions for real-time events - name: Reference description: Look up available types, scopes, and events - name: Social description: >- Zernio-backed social posting and reviews across all connected platforms (X, Facebook, Instagram, LinkedIn, Google Business Profile) - name: Health description: Health check (no authentication) paths: /comparisons: post: tags: - Content summary: Create vehicle comparison description: | Creates a vehicle comparison comparing 2-5 vehicles side-by-side. The comparison is generated asynchronously. Use the returned `id` with `GET /content/{id}` to check status and retrieve the result. operationId: createComparison requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CreateComparisonInput' responses: '202': description: Comparison generation started content: application/json: schema: $ref: '#/components/schemas/ComparisonCreatedResponse' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '500': $ref: '#/components/responses/InternalError' components: schemas: CreateComparisonInput: type: object required: - vehicles properties: vehicles: type: array minItems: 2 maxItems: 5 items: $ref: '#/components/schemas/ComparisonVehicle' brand_voice_id: type: string description: ID of a brand voice profile to use for tone and style language: type: string enum: - English - Spanish - Mandarin Chinese - Japanese - Korean - Arabic - Farsi - Hebrew - French - Tagalog - Vietnamese - Portuguese - Russian default: English title: type: string maxLength: 500 description: Custom title. Defaults to "Vehicle A vs Vehicle B vs ..." content_length: type: integer minimum: 200 maximum: 5000 deprecated: true description: > **Deprecated.** Article length is now driven by `content_depth`; this field is accepted for backward compatibility but has no effect. Comparison articles always include data tables. content_depth: type: string enum: - concise - steady - balanced - substantial - in-depth description: > Content depth preset that drives the article body. Defaults to `balanced`. Replaces the legacy `content_length` field. featured_vehicle_index: type: integer minimum: 0 maximum: 2 description: > Zero-based index of the vehicle to favor in the comparison. Omit for neutral/equal treatment of all vehicles. bias_level: type: integer minimum: 0 maximum: 100 description: > Bias intensity toward the featured vehicle (0-100). 0 = Neutral, 25 = Subtle, 50 = Moderate (default), 75 = Strong, 100 = Maximum. Only applies when featured_vehicle_index is set. ComparisonCreatedResponse: type: object properties: data: type: object properties: id: type: string format: uuid status: $ref: '#/components/schemas/ContentStatus' article_type: type: string example: comparison title: type: string vehicles: type: array items: $ref: '#/components/schemas/ComparisonVehicle' featured_vehicle_index: type: integer nullable: true description: Index of the featured vehicle, or null if neutral bias_level: type: integer nullable: true description: Bias intensity (0-100), or null if not set created_at: type: string format: date-time message: type: string description: >- Informational message about async processing and webhook configuration ComparisonVehicle: type: object required: - year - make - model properties: year: type: integer minimum: 1900 maximum: 2100 example: 2026 make: type: string minLength: 1 maxLength: 100 example: Toyota model: type: string minLength: 1 maxLength: 100 example: Camry trim: type: string maxLength: 200 example: XSE ContentStatus: type: string enum: - generating - complete - failed description: Content generation status ErrorResponse: type: object properties: error: type: object properties: code: type: string example: validation_error message: type: string example: 'keyword: Required' details: type: object request_id: type: string responses: BadRequest: description: Validation error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' Unauthorized: description: Missing or invalid API key content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' Forbidden: description: API key lacks required scope content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' InternalError: description: Internal server error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' securitySchemes: apiKeyAuth: type: apiKey in: header name: X-API-Key description: Your Hrizn API key (prefix hzk_) ````