> ## Documentation Index > Fetch the complete documentation index at: https://developers.thinkout.io/llms.txt > Use this file to discover all available pages before exploring further. # List categories > Returns the category tree flattened, in the order ThinkOut displays it: inflows first, then outflows, and within each direction every root followed immediately by its own children. Siblings follow `position`. Reading the page top to bottom therefore gives the product's own category screen. `direction` narrows to one of its two panels. Rebuild the hierarchy with `parent_id`, and re-sort with `position` within each `parent_id` if you need the order again after storing the rows. The tree is exactly two levels deep. A category with a `parent_id` never has children of its own, and both levels can appear on a transaction. A child's `direction` and `activity` always match its root's. ## OpenAPI ````yaml /openapi/v1.yaml get /categories openapi: 3.1.0 info: title: ThinkOut API version: '1.0' description: > Programmatic access to the data of a ThinkOut workspace. Every endpoint in version 1 is a `GET`. Lists share one response envelope, and page with a cursor wherever the list can grow. Version 1 changes additively. New endpoints, new optional parameters, new response fields and new enum values can appear at any time, so tolerate unknown fields and never treat an enum as a closed set. contact: name: ThinkOut developer support url: https://developers.thinkout.io/guides/support servers: - url: https://api.thinkout.io/v1 security: - apiKey: [] tags: - name: Banks description: The workspace's bank connections and the state of each one. - name: Accounts description: Manual, bank-synced and delegated accounts with computed balances. - name: Transactions description: Booked and pending movements on the workspace's accounts. - name: Categories description: The workspace category tree, split by direction and business activity. - name: Counterparties description: Customers and suppliers that transactions and forecasts are attributed to. - name: Labels description: Free-form tags grouped by label type. - name: Forecasts description: Planned inflows and outflows and the transactions that realised them. - name: Reports description: >- Totals rather than rows. Summaries over transactions and forecasts, and the workspace's own saved cash flow views. paths: /categories: get: tags: - Categories summary: List categories description: > Returns the category tree flattened, in the order ThinkOut displays it: inflows first, then outflows, and within each direction every root followed immediately by its own children. Siblings follow `position`. Reading the page top to bottom therefore gives the product's own category screen. `direction` narrows to one of its two panels. Rebuild the hierarchy with `parent_id`, and re-sort with `position` within each `parent_id` if you need the order again after storing the rows. The tree is exactly two levels deep. A category with a `parent_id` never has children of its own, and both levels can appear on a transaction. A child's `direction` and `activity` always match its root's. operationId: listCategories parameters: - $ref: '#/components/parameters/direction' - $ref: '#/components/parameters/limit' - $ref: '#/components/parameters/cursor' responses: '200': description: A page of categories. content: application/json: schema: allOf: - $ref: '#/components/schemas/List' - type: object properties: data: type: array items: $ref: '#/components/schemas/Category' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '429': $ref: '#/components/responses/RateLimited' components: parameters: direction: name: direction in: query schema: $ref: '#/components/schemas/Direction' limit: name: limit in: query description: Page size. schema: type: integer minimum: 1 maximum: 500 default: 100 cursor: name: cursor in: query description: Opaque token from the previous page's `next_cursor`. schema: type: string schemas: List: type: object required: - object - data - has_more - next_cursor properties: object: type: string const: list data: type: array items: {} has_more: type: boolean description: Whether another page exists. next_cursor: type: - string - 'null' description: Pass as `cursor` to fetch the next page. `null` on the last page. Category: type: object required: - object - id - name - code - direction - activity - parent_id - position - color - created_at - updated_at properties: object: type: string const: category id: type: string format: uuid name: type: string example: Telecom code: type: - string - 'null' description: > The category's identifier in the template this workspace was created from. `null` for a category someone created. Only `uncategorized_inflows` and `uncategorized_outflows` are worth branching on. They mark the two categories holding unclassified money, they exist in every workspace, and ThinkOut refuses to delete them. Every other code depends on which template was used. example: uncategorized_outflows direction: $ref: '#/components/schemas/Direction' activity: $ref: '#/components/schemas/Activity' parent_id: type: - string - 'null' format: uuid description: '`null` for top-level categories.' position: type: integer description: Order among siblings, as shown in ThinkOut. color: type: - string - 'null' description: Lowercase hex color as shown in ThinkOut. pattern: ^#[0-9a-f]{6}$ example: '#1b7fe4' created_at: type: string format: date-time updated_at: type: string format: date-time example: object: category id: 3b4c5d6e-7f80-4a1b-9c2d-3e4f5a6b7c8d name: Telecom code: null direction: outflow activity: operating parent_id: 6a7b8c9d-0e1f-4a2b-8c3d-4e5f6a7b8c9d position: 2 color: '#1b7fe4' created_at: '2024-01-01T10:00:00Z' updated_at: '2024-01-01T10:00:00Z' Direction: type: string description: > Whether money comes in or goes out. On a transaction or a forecast it follows the sign of `amount` and can never disagree with it. It is present so that responses can be grouped and read without inspecting signs. enum: - inflow - outflow Activity: type: string description: Cash flow statement section the category belongs to. enum: - operating - investing - financing Error: type: object required: - error properties: error: type: object required: - type - code - message - param - request_id properties: type: type: string enum: - invalid_request - authentication - not_found - rate_limit - server code: type: string description: > Stable machine-readable reason. Branch on this, not on `message`. Report-specific codes are `too_many_groups`, `period_too_long`, `as_of_in_future` and `invalid_expand`. message: type: string description: Human-readable explanation. Wording may change. param: type: - string - 'null' description: The query or path parameter at fault, when there is one. request_id: type: string description: Quote this when contacting support. responses: BadRequest: description: A parameter is invalid. content: application/json: schema: $ref: '#/components/schemas/Error' example: error: type: invalid_request code: invalid_parameter message: Parameter 'from' must be a date in YYYY-MM-DD format. param: from request_id: req_01J8ZT4Q7Y6M3K Unauthorized: description: The API key is missing, unknown or revoked. content: application/json: schema: $ref: '#/components/schemas/Error' example: error: type: authentication code: unauthorized message: Invalid API key. param: null request_id: req_01J8ZT4Q7Y6M3K RateLimited: description: Too many requests. Wait for the number of seconds in `Retry-After`. headers: Retry-After: schema: type: integer description: Seconds to wait before retrying. content: application/json: schema: $ref: '#/components/schemas/Error' example: error: type: rate_limit code: rate_limited message: Rate limit exceeded. Retry after 12 seconds. param: null request_id: req_01J8ZT4Q7Y6M3K securitySchemes: apiKey: type: http scheme: bearer description: >- A workspace API key created in ThinkOut settings. One key reads one workspace. ````