> ## Documentation Index > Fetch the complete documentation index at: https://docs.sailresearch.com/llms.txt > Use this file to discover all available pages before exploring further. # Mint a download URL for a file > Returns a URL that serves one file over HTTPS with no API key. The URL authorizes reading that file alone and serves whatever the file holds when it is fetched. [Share a file by URL](/sailboxes-http-api#share-a-file-by-url) covers the response headers, caching, and sleeping or paused Sailboxes. ## OpenAPI ````yaml /sailbox-openapi.json post /sailboxes/{sailbox_id}/files/download-url openapi: 3.1.0 info: title: Sail Sailbox API version: '2026-09-07' description: >- Create and operate Sailboxes over HTTP. Sailboxes are fast-booting virtual machines that you can pause, resume, and checkpoint. Run commands, stream files, manage lifecycle and networking, and inspect usage. Turning on SSH and building an image still require an SDK or the CLI. See the [HTTP API guide](/sailboxes-http-api). servers: - url: https://sailbox-api.sailresearch.com/v1 security: - BearerAuth: [] tags: - name: Apps description: Groups that own Sailboxes. One app per workload. - name: Lifecycle description: >- A Sailbox's whole life: create it, watch it, stop and start it, terminate it. - name: Checkpoints description: Save a Sailbox to start from later, and copy a running one. - name: Exec description: Run commands and control their standard input and terminals. - name: Files description: Stream regular files into and out of a Sailbox. - name: Networking description: >- Publish ports, serve them on hostnames you own, and identify a Sailbox to other Sailboxes. - name: Secrets description: >- Organization values that egress policy rules can add to matching requests. Sail never returns a stored value. - name: Egress policies description: >- What a Sailbox may connect to, and what happens to the HTTPS requests it sends. - name: Volumes description: >- Shared storage that outlives any one Sailbox. Alpha: these endpoints can still change. - name: SSH access description: Certificates for connecting to a Sailbox with `ssh`. - name: Usage description: Resource usage and spend. - name: Identity description: Who your API key belongs to. paths: /sailboxes/{sailbox_id}/files/download-url: post: tags: - Files summary: Mint a download URL for a file description: >- Returns a URL that serves one file over HTTPS with no API key. The URL authorizes reading that file alone and serves whatever the file holds when it is fetched. [Share a file by URL](/sailboxes-http-api#share-a-file-by-url) covers the response headers, caching, and sleeping or paused Sailboxes. operationId: createSailboxFileDownloadUrl parameters: - $ref: '#/components/parameters/SailboxId' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/SailboxFileDownloadUrlRequest' example: path: /workspace/render.png expires_in_seconds: 3600 responses: '200': description: The URL and when it stops working. content: application/json: schema: $ref: '#/components/schemas/SailboxFileDownloadUrl' example: url: >- https://sailbox-api.sailresearch.com/v1/sailboxes/sb_9c8f1e2a-3b4d-4f5a-8c7e-1d2f3a4b5c6d/files/download?expires=1767225600&path=%2Fworkspace%2Frender.png&sig=Yx3n4x1p9Q8b2Vf7K0mZcJtR6wLaHd5eGsUoNiA8PkE expires_at: '2026-01-01T00:00:00Z' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '402': $ref: '#/components/responses/PaymentRequired' '403': $ref: '#/components/responses/Forbidden' '404': $ref: '#/components/responses/NotFound' '409': $ref: '#/components/responses/Conflict' '413': $ref: '#/components/responses/BodyTooLarge' '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/ServerError' '503': $ref: '#/components/responses/Unavailable' components: parameters: SailboxId: name: sailbox_id in: path required: true schema: type: string description: >- Id of the Sailbox, as returned by create. It is `sb_` followed by a UUID. schemas: SailboxFileDownloadUrlRequest: type: object required: - path properties: path: type: string minLength: 1 description: >- Absolute path of the file inside the Sailbox. The file is read when the URL is fetched, so it does not have to exist when the URL is minted. expires_in_seconds: type: integer format: int64 minimum: 1 maximum: 604800 default: 3600 description: >- How long the URL stays valid, up to seven days. Expiry only stops new fetches; copies already downloaded or cached are unaffected. attachment: type: boolean default: false description: >- Serve the file as a download (`Content-Disposition: attachment`) instead of inline. immutable: type: boolean default: false description: >- Mark the response cacheable for a year, so a cache that holds a copy never checks back. Use it only for a path you never overwrite. SailboxFileDownloadUrl: type: object properties: url: type: string format: uri description: >- The signed URL. Anyone who holds it can read this one file until it expires. expires_at: type: string format: date-time description: When the URL stops working. required: - url - expires_at ErrorResponse: type: object required: - error properties: error: $ref: '#/components/schemas/ErrorObject' ErrorObject: type: object required: - message - type - param - code properties: message: type: string description: Human-readable description of what went wrong. type: type: string description: >- Error category: `invalid_request_error`, `authentication_error`, `permission_error`, `billing_error`, `not_found_error`, `conflict_error`, `rate_limit_error`, `quota_exceeded_error`, `not_implemented_error`, or `server_error`. param: oneOf: - type: string - type: 'null' description: >- The request field the error refers to, when the error is about one field. code: oneOf: - type: string - type: integer - type: 'null' description: >- Stable short code for the error, when one applies. Errors relayed from the Sailbox runtime carry its status token, for example `already_exists` or `failed_precondition` on a 409, which the HTTP status alone does not distinguish. billing_url: type: string format: uri description: Page where you add credits. Sent with a 402. additionalProperties: true responses: BadRequest: description: The request was rejected. See the error message for the offending field. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: memory_limit_gib for size m must be between 8 and 128 type: invalid_request_error param: null code: null Unauthorized: description: The API key is missing or invalid. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: Invalid API key type: authentication_error param: null code: invalid_api_key PaymentRequired: description: >- The organization is out of credits. The error carries a `billing_url` pointing at the page where you add them. Retry once you have. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: >- Your API key has been disabled due to insufficient credits. Visit https://app.sailresearch.com/billing to add credits. type: billing_error param: null code: credits_exhausted billing_url: https://app.sailresearch.com/billing Forbidden: description: The API key is not allowed to perform this operation. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: sailboxes require an organization-scoped API key type: permission_error param: null code: null NotFound: description: No Sailbox with that id exists in your organization. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: sailbox "sb_9c8f1e2a-3b4d-4f5a-8c7e-1d2f3a4b5c6d" not found type: not_found_error param: null code: null Conflict: description: The Sailbox is not in a state that allows this operation. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: sailbox listeners require persistence type: conflict_error param: null code: null BodyTooLarge: description: The request body is larger than the 64 KiB this endpoint accepts. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: request body too large type: invalid_request_error param: null code: null TooManyRequests: description: >- Too many requests in flight, or the organization is at a limit. A `Retry-After` header means the request never started, so retry it unchanged after that delay. Without one, the request ran and hit the limit `message` names. Some of those clear on their own, such as a shortage of public ports; others need you to free something up first. Send the request again once the cause is gone. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: >- Too many concurrent requests. Please retry after some of your organization's in-flight requests complete. type: rate_limit_error param: null code: rate_limited headers: Retry-After: $ref: '#/components/headers/RetryAfter' ServerError: description: Server error. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: failed to fetch sailbox type: server_error param: null code: null Unavailable: description: >- Sail is momentarily unavailable. Retry after the delay in the `Retry-After` header when one is present, and with backoff otherwise. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: Authentication service unavailable type: server_error param: null code: null headers: Retry-After: $ref: '#/components/headers/RetryAfter' headers: RetryAfter: description: >- How many seconds to wait before retrying. On a 429 it also means the request never started, so the retry can reuse the same `Idempotency-Key`. schema: type: integer minimum: 0 securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: API Key ````