> ## Documentation Index > Fetch the complete documentation index at: https://docs.ai2fin.com/llms.txt > Use this file to discover all available pages before exploring further. # Get categories for multiple transactions > Fetch category assignments for many transactions in a single request. Use this instead of calling GET /api/transaction-categories/{transactionId} once per transaction; it collapses what would be N requests into one. Accepts up to 500 transaction IDs per call. Unknown or not-yet-categorized IDs are returned with an empty array. ## OpenAPI ````yaml /api-reference/openapi.json post /api/transaction-categories/batch openapi: 3.1.0 info: title: AI2Fin Financial Management API description: >- Financial management platform with AI-powered categorization, tax optimization, and bill management. version: 1.0.0 contact: name: AI2Fin Support url: https://ai2fin.com license: name: Proprietary servers: - url: https://api.ai2fin.com description: Production - url: http://localhost:3001 description: Local Development security: - bearerAuth: [] - cookieAuth: [] tags: - name: Authentication description: User authentication and authorization - name: Bank Transactions description: >- First-party endpoints for managing your own transactions and CSV imports. These return your own account data in your own authenticated session; they are not a third-party integration surface. Data synced from connected bank feeds (open-banking / CDR data) stays within your account and is only ever returned to you. - name: Bills & Recurring Payments description: Bill management with pattern recognition and auto-linking - name: Expenses description: Expense tracking with tax deduction support - name: AI Services description: AI-powered categorization and tax analysis - name: Automation description: Custom rules engine for automated workflows - name: Categories description: Transaction and expense category management - name: Smart Categories description: >- Category sets, multi-category assignments, and transaction history (Elite+ only) - name: Analytics & Reports description: Financial analytics and tax report generation - name: Travel & Vehicles description: Vehicle registration and business trip tracking - name: Search description: AI-powered unified search across all entities - name: Subscription description: Subscription and quota management - name: AI Analysis description: AI-driven categorization and tax analysis endpoints - name: AI Assistant description: Chat conversations, messaging, and assistant file handling - name: GST & Tax description: Global GST/VAT rate lookup and calculations - name: Receipts & Attachments description: Receipt ingestion, AI analysis, and linkage APIs - name: MCP Server description: >- Model Context Protocol endpoints for AI integrations. Finance MCP server with 65+ tools for expense tracking, tax deductions, bill management, and financial analysis. Supports OAuth (JWT) and API key authentication. paths: /api/transaction-categories/batch: post: tags: - Smart Categories summary: Get categories for multiple transactions description: >- Fetch category assignments for many transactions in a single request. Use this instead of calling GET /api/transaction-categories/{transactionId} once per transaction; it collapses what would be N requests into one. Accepts up to 500 transaction IDs per call. Unknown or not-yet-categorized IDs are returned with an empty array. requestBody: required: true content: application/json: schema: type: object required: - transactionIds properties: transactionIds: type: array description: >- Transaction IDs to fetch categories for (maximum 500 per request). items: type: string responses: '200': description: Category assignments keyed by transaction ID content: application/json: schema: type: object properties: success: type: boolean categories: type: object description: >- Map of transaction ID to its category assignments. Every requested ID is present; a transaction with no categories maps to an empty array. additionalProperties: type: array items: $ref: '#/components/schemas/TransactionCategory' components: schemas: TransactionCategory: type: object description: >- A category assignment for a transaction. Transactions can have multiple categories from different sets. properties: id: type: string transactionId: type: string categoryId: type: string categorySetId: type: string userId: type: string isPrimary: type: boolean description: Whether this is the primary category for the transaction confidence: type: number minimum: 0 maximum: 1 description: AI confidence score for the assignment assignedBy: type: string enum: - user - ai - import - rule - bulk description: Source of the category assignment assignedAt: type: string format: date-time notes: type: string category: $ref: '#/components/schemas/Category' Category: type: object properties: id: type: string name: type: string icon: type: string color: type: string isTaxDeductible: type: boolean taxCategory: type: string defaultGstRate: type: number securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: JWT description: >- First-party access token for your own signed-in session, obtained from the /api/enterprise-auth/login endpoint. The REST API returns your own account data to you — it is a first-party consumer surface, not a third-party integration channel. Data from connected bank feeds (open-banking / CDR data) is your own data, returned only to you in your own authenticated session. cookieAuth: type: apiKey in: cookie name: ai2_sess description: Session cookie for web applications ````