> ## Documentation Index > Fetch the complete documentation index at: https://docs.comfy.org/llms.txt > Use this file to discover all available pages before exploring further. # Asset metadata > Returns the asset object with a fresh short-lived `url` for the content. Re-fetching always yields fresh URLs. ## OpenAPI ````yaml /openapi-v2.yaml get /api/v2/assets/{id} openapi: 3.0.3 info: title: Comfy API v2 version: 2.0.0 description: | The official, versioned HTTP API for running ComfyUI workflows from external applications: upload inputs, submit a workflow, observe execution, retrieve results. Design principles: - **Poll-first.** Every capability is reachable via plain GET polling; the SSE stream is a live enhancement, never the source of truth. - **Everything is resumable.** Submission is idempotent; job state and outputs are retrievable by ID until `expires_at`. - **UUID identity, content-addressed dedup.** Assets are UUID-identified records over blobs keyed by a server-computed blake3 hash. The hash is nullable and may be computed lazily. - **Follow links, don't build URLs.** Responses embed follow-up URLs. Additive changes only within v2; breaking changes require v3. servers: - url: http://127.0.0.1:8189 description: Self-hosted (comfy-api-proxy) - url: https://cloud.comfy.org description: Comfy Cloud - url: https://{deployment}.run.comfy.app description: Serverless deployment variables: deployment: description: >- DNS-safe deployment id (subdomain label). Staging uses {deployment}.stg.run.comfy.app. default: dep-1234abcd-56ef-7890-abcd-ef1234567890 security: - bearerAuth: [] - {} tags: - name: assets description: UUID-identified records over content-addressed blobs. - name: jobs description: One execution of a workflow — durable, pollable, cancelable. paths: /api/v2/assets/{id}: get: tags: - assets summary: Asset metadata description: >- Returns the asset object with a fresh short-lived `url` for the content. Re-fetching always yields fresh URLs. operationId: getAsset parameters: - $ref: '#/components/parameters/AssetId' responses: '200': description: The asset. content: application/json: schema: $ref: '#/components/schemas/Asset' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '404': $ref: '#/components/responses/NotFound' '429': $ref: '#/components/responses/RateLimited' '500': $ref: '#/components/responses/UpstreamError' '503': $ref: '#/components/responses/DeploymentLookupUnavailable' components: parameters: AssetId: name: id in: path required: true schema: type: string example: 9f8a1c0d-2b3e-4f56-8a7b-1c2d3e4f5a6b schemas: Asset: type: object description: >- A user-owned record identified by a server-assigned UUID, backing an immutable blob whose content carries a server-computed blake3 hash. `hash` may be computed lazily: an asset record (and its retrievable bytes) can exist before its hash is filled in. On an output, `job_metadata` carries the labels its producing job was submitted with, so code holding only the asset knows which run it came from. It is absent for assets no job produced, for outputs of a job sent without labels, where the serving surface keeps no job labels, and when the labels could not be read: so `job_id` without `job_metadata` does not prove the job had no labels. A create whose file path and bytes match an existing output answers with that output, so its `job_id` and `job_metadata` are the output's. required: - id - hash - size_bytes - content_type - created_at - url - url_expires_at properties: id: type: string example: 9f8a1c0d-2b3e-4f56-8a7b-1c2d3e4f5a6b hash: type: string nullable: true description: '`blake3:`; null while lazily computed.' example: blake3:9f8a1c0d... size_bytes: type: integer format: int64 example: 4816293 content_type: type: string example: image/png file_path: type: string nullable: true example: photo.png created_new: type: boolean description: >- On create responses: distinguishes a brand-new blob (true) from a dedup hit against bytes the platform already had (false). created_at: type: string format: date-time url: type: string format: uri description: Short-lived content URL (signed, or proxy-served). url_expires_at: type: string format: date-time expires_at: type: string format: date-time nullable: true description: >- Retention deadline for the asset itself (distinct from `url_expires_at`, the signed URL's validity). Null or absent means the asset is non-expiring. On a dedup-hit create response the deadline may be later than now + the requested/default retention: re-referencing content extends its retention, never shortens it. job_id: type: string nullable: true description: >- ID of the job that produced this asset. Absent for assets no job produced, such as a fresh upload. job_metadata: allOf: - $ref: '#/components/schemas/JobMetadata' description: >- The labels the producing job was submitted with, read through `job_id` on each read. Absent for assets no job produced, for outputs of a job sent without labels, where the serving surface keeps no job labels, when the job is gone, and when the labels could not be read: so `job_id` without `job_metadata` does not prove the job had no labels. JobMetadata: type: object description: >- The labels the job was submitted with, exactly as sent. Absent when it was sent with none. additionalProperties: type: string example: client: acme ErrorEnvelope: type: object description: | Shared error envelope with machine-readable codes. Core codes (v1): `invalid_workflow` (422), `workflow_format_ui` (422), `missing_asset` (422), `hash_mismatch` (409), `blob_not_found` (404), `idempotency_key_reuse` (422), `upload_timed_out` (422: an asset upload stopped sending or was too slow; retry from a faster connection), `queue_full` (429 + Retry-After), `rate_limited` (429 + Retry-After: the caller is past a request rate limit; retry), `insufficient_credits` (402), `not_found` (404), `unauthorized` (401), `forbidden` (403). Deployment-scoped surfaces add: `deployment_not_ready` (429 + Retry-After — the deployment can still reach ready; retry), `deployment_unavailable` (429 + Retry-After: the deployment is ready but its GPU provider is not taking work on it yet; retry), `deployment_lookup_unavailable` (503 + Retry-After, on any operation: the deployment the address names could not be looked up just now; nothing was done, so retry), `database_unavailable` (503 + Retry-After, only on a job submit: the job could not be saved just now and nothing was started, so retry), `auth_unavailable` (503 + Retry-After, on any operation: the credential could not be checked just now, which says nothing about the credential, so retry), `output_unavailable` (503 + Retry-After, only on a job status read: an output of the job could not be prepared just now; the job is unchanged, so retry after `Retry-After`, and report the job if it keeps answering), `deployment_stopped` (422 — terminal deployment state; a retry cannot succeed without operator action), `invalid_request` (422: a malformed asset upload or asset-from-hash field, or a jobs-list `limit` that is not a positive integer), `validation_error` (422, Cloud: an asset upload or asset-from-hash field was refused, e.g. a tag over the tag limits), `content_blocked` (451: content moderation flagged the asset's bytes) and `sso_required` (403: the key is valid, but the account must sign in through its organization's single sign-on, which does not accept this key). Comfy Cloud's asset upload adds `invalid_content_type` (422: the request is not `multipart/form-data` with a boundary), `invalid_body` (422: a malformed multipart body or upload field), `validation_error` (422: the platform refused the upload, for example an image over the size cap or a disallowed tag) and `upload_busy` (503 + Retry-After: the server is busy with other uploads and nothing was stored, so retry). Job labels add: `metadata_invalid` (422: a submitted `metadata` breaks a limit; `details.key` names the key, except for too many pairs, which has no `details`), `metadata_not_supported` (422: this surface keeps no job labels yet), `invalid_metadata_filter` (400) and `invalid_cursor` (400). A surface that does not list jobs yet answers `not_implemented` (501). A 429 is disambiguated by `error.code` alone; clients should treat any 429 + Retry-After as "back off and retry". required: - error properties: error: type: object required: - code - message properties: code: type: string example: invalid_workflow message: type: string example: 'Node 12 (KSampler): required input ''model'' is not connected' organization_id: type: string description: >- On `sso_required`: the organization whose single sign-on governs this key, the one that holds the account, else the one that holds the key's workspace. It is the `organization` query parameter of Comfy Cloud's single sign-on start; treat it as opaque. Absent when the organization is unknown, and on every other code. example: org_01HXYZEXAMPLE details: type: object nullable: true additionalProperties: true description: >- Machine-readable detail for the code. When it carries `node_errors`, that is keyed by node id and each value is a `JobNodeError`, the same shape as a job's `error.node_errors`, whether the refusal came at submit (for example `unknown_node_class`, a node class the deployment's build does not contain) or from ComfyUI after dispatch. With `unknown_node_class` errors it carries `unknown_node_classes`, the missing classes; with `waits_for_browser` errors, `browser_wait_node_classes`, the classes that wait for a browser. A submit refusal names at most fifty nodes. For `invalid_node`, `invalid_inputs` and `invalid_class_type`, when it found more than fifty, `node_errors_truncated` is true and `malformed_node_count` carries the full count; for `waits_for_browser`, `browser_wait_node_count` does. For `unknown_node_class` it names only nodes whose class is one of the at most ten listed in `unknown_node_classes`; when those nodes number more than fifty, `node_errors_truncated` is true and `unknown_node_count` is how many nodes have a listed class. Nodes whose class is past those ten are neither named nor counted. example: node_errors: '12': class_type: SomeCustomNode errors: - type: unknown_node_class message: >- this deployment's build does not contain the node class SomeCustomNode. unknown_node_classes: - SomeCustomNode responses: Unauthorized: description: >- `unauthorized`: missing or invalid credentials. A credential that could not be checked answers `auth_unavailable` (503) instead. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' Forbidden: description: >- `forbidden` — authenticated but not allowed. On a serverless deployment, also `sso_required` — the key is valid, but the account must sign in through its organization's single sign-on, which does not accept this key; it can come back on any operation. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' NotFound: description: '`not_found`.' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' RateLimited: description: >- `rate_limited` — the caller has exceeded a request rate limit for this account. Account/rate-scoped, not resource-specific — this can be returned even for a job, asset or deployment the caller doesn't own or that doesn't exist. headers: Retry-After: $ref: '#/components/headers/RetryAfter' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' UpstreamError: description: >- `upstream_error` — an unexpected failure reaching or processing the request in this implementation's backing services. The message is always a generic, safe-to-display string; implementation detail (the specific upstream, its error text, transport failures) is never included here — see each implementation's own error-mapping notes. Every operation in this contract can fail this way. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' DeploymentLookupUnavailable: description: >- On deployment-scoped surfaces, `deployment_lookup_unavailable`: the deployment this address names could not be looked up just now. The request was refused before it did anything (nothing was created, read, changed or canceled), so the same request can be sent again after `Retry-After`. Every operation at a deployment's address can answer this way. A job submit can also answer this 503 with `database_unavailable`: the job could not be saved just now and nothing was started, so the same request can be sent again after `Retry-After`. No other operation answers `database_unavailable`. On Comfy Cloud an asset upload can also answer this 503 with `upload_busy`: the server is busy with other uploads and nothing was stored, so the same upload can be sent again after `Retry-After`. Any operation can also answer this 503 with `auth_unavailable`: the credential could not be checked just now, so the same request can be sent again after `Retry-After`. A job status read can also answer it with `output_unavailable`: an output of the job could not be prepared just now, and the job is unchanged. A transient storage failure clears on a later read after `Retry-After`; an output whose stored address is broken answers it on every read until the platform repairs the output. headers: Retry-After: $ref: '#/components/headers/RetryAfter' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' headers: RetryAfter: schema: type: integer description: Seconds to wait before retrying. securitySchemes: bearerAuth: type: http scheme: bearer description: >- `Authorization: Bearer `. The credential is one of: an account-scoped API key (`comfyui-…`), accepted on Cloud and serverless; a Comfy Cloud session JWT; or an OAuth access token issued for the Comfy Cloud resource. Which kinds a given deployment accepts is deployment configuration — an API key always works on Cloud and serverless, and a deployment that does not accept JWT bearers answers `401` with a message saying so. Self-hosted accepts unauthenticated requests by default and can be configured with a static bearer token. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.