> ## Documentation Index > Fetch the complete documentation index at: https://docs.lambdadb.ai/llms.txt > Use this file to discover all available pages before exploring further. # Create a tag > Pin a committed snapshot from a branch or tag in the same collection as an immutable tag. A tag source pins the same snapshot, not a chain of tags. Alias sources are not allowed, and source.asOf is valid only for a branch source. Omit source to use main. An empty head or unavailable asOf history returns 400; verify committed data before tagging. ## OpenAPI ````yaml post /collections/{collectionName}/tags openapi: 3.1.1 info: title: LambdaDB API summary: LambdaDB Open API Spec version: 1.1.1 servers: - url: https://{projectHost} description: LambdaDB API endpoints variables: projectHost: description: The project-scoped URL of the API default: api.lambdadb.ai/projects/example-project security: [] tags: - name: collections description: Create, describe, configure, list, and delete collections. - name: versioning description: Manage branches, tags, and aliases within a collection. - name: collections.docs description: Write, fetch, list, and bulk upload documents. paths: /collections/{collectionName}/tags: post: tags: - versioning summary: Create a Tag description: >- Pin a committed snapshot from a branch or tag in the same collection as an immutable tag. A tag source pins the same snapshot, not a chain of tags. Alias sources are not allowed, and source.asOf is valid only for a branch source. Omit source to use main. An empty head or unavailable asOf history returns 400; verify committed data before tagging. operationId: createTag parameters: - $ref: '#/components/parameters/CollectionName' requestBody: required: true content: application/json: schema: type: object additionalProperties: false properties: tagName: type: string minLength: 3 maxLength: 52 pattern: ^[a-zA-Z0-9_-]{3,52}$ source: $ref: '#/components/schemas/RefSource' required: - tagName examples: example: value: tagName: validated-2026-09 source: kind: branch name: candidate responses: '201': description: Tag created. content: application/json: schema: type: object properties: tag: $ref: '#/components/schemas/TagDetails' required: - tag examples: example: value: tag: name: validated-2026-09 snapshotId: snapshot-id createdAt: 1788336000000 snapshotCommittedAt: 1788335940000 '400': description: Bad request content: application/json: schema: $ref: '#/components/schemas/BadRequest' examples: example: summary: Example response for bad request value: message: Invalid request '401': description: Unauthenticated content: application/json: schema: $ref: '#/components/schemas/Unauthenticated' examples: example: summary: Example response for authentication failure value: message: Authentication failed '404': $ref: '#/components/responses/ResourceNotFound' '409': description: Resource already exists content: application/json: schema: $ref: '#/components/schemas/ResourceAlreadyExists' examples: example: summary: Example response for resource already exists value: message: Resource already exists '413': $ref: '#/components/responses/PayloadTooLarge' '429': description: Too many requests content: application/json: schema: $ref: '#/components/schemas/TooManyRequests' examples: example: summary: Example response for too many requests value: message: Too many requests headers: Retry-After: description: >- Optional retry delay in seconds. Not present on every 429 response. schema: type: string '500': description: Internal server error content: application/json: schema: $ref: '#/components/schemas/InternalServerError' examples: example: summary: Example response for internal server error value: message: Internal server error '502': $ref: '#/components/responses/BadGateway' '503': $ref: '#/components/responses/ServiceUnavailable' '504': $ref: '#/components/responses/GatewayTimeout' security: - ProjectApiKey: [] components: parameters: CollectionName: in: path name: collectionName description: Collection name. required: true schema: type: string schemas: RefSource: title: RefSource oneOf: - $ref: '#/components/schemas/BranchSource' - title: Tag source type: object additionalProperties: false properties: kind: type: string enum: - tag name: type: string minLength: 3 maxLength: 52 pattern: ^[a-zA-Z0-9_-]{3,52}$ required: - kind - name TagDetails: title: TagDetails type: object properties: name: type: string snapshotId: type: string description: >- Immutable snapshot pinned by the tag. A tag cannot pin an empty head. snapshotCommittedAt: type: integer format: int64 description: Pinned snapshot commit time as Unix epoch milliseconds. createdAt: type: integer format: int64 description: >- Tag creation time as Unix epoch milliseconds, independent of the pinned snapshot commit time. required: - name - snapshotId - snapshotCommittedAt - createdAt BadRequest: title: BadRequest type: object properties: message: type: string Unauthenticated: title: Unauthenticated type: object properties: message: type: string ResourceAlreadyExists: title: ResourceAlreadyExists type: object properties: message: type: string TooManyRequests: title: TooManyRequests type: object properties: message: type: string InternalServerError: title: InternalServerError type: object properties: message: type: string BranchSource: title: Branch source type: object additionalProperties: false properties: kind: type: string enum: - branch name: type: string minLength: 3 maxLength: 52 pattern: ^[a-zA-Z0-9_-]{3,52}$ asOf: type: integer format: int64 description: Latest committed snapshot cutoff as Unix epoch milliseconds. required: - kind - name ResourceNotFound: title: ResourceNotFound type: object properties: message: type: string MessageResponse: type: object properties: message: type: string required: - message responses: ResourceNotFound: description: Resource not found content: application/json: schema: $ref: '#/components/schemas/ResourceNotFound' examples: example: summary: Example response for resource not found value: message: Resource not found PayloadTooLarge: description: >- Request exceeds the Gateway transport limit. Reduce the request size or use bulk upsert when supported. content: application/json: schema: $ref: '#/components/schemas/MessageResponse' BadGateway: description: >- Unexpected downstream failure. A failed write response may leave its outcome uncertain. content: application/json: schema: $ref: '#/components/schemas/MessageResponse' ServiceUnavailable: description: >- Transient catalog or storage dependency failure. Use bounded retries where the operation permits. content: application/json: schema: $ref: '#/components/schemas/MessageResponse' GatewayTimeout: description: >- Gateway request deadline exceeded. A write may have been applied; verify its outcome before retrying. content: application/json: schema: $ref: '#/components/schemas/MessageResponse' securitySchemes: ProjectApiKey: type: apiKey in: header name: x-api-key description: Project API Key. x-speakeasy-example: ````