AIR identifiers

An AI Resource Identifier (AIR) is the canonical URN-style string Civitai uses to reference any AI resource — a checkpoint, LoRA, VAE, embedding, or upscaler — consistently across the site API, the Orchestration API, and partner integrations.

Every response from GET /model-versions/{id} includes an air field you can pass directly to generation APIs.

Format

urn:air:{ecosystem}:{type}:{source}:{id}[@{version}][+{fileId}][.{format}]

The urn: and air: prefixes are both optional — parsers accept urn:air:sdxl:checkpoint:civitai:827184@2514310, air:sdxl:checkpoint:civitai:827184@2514310, and bare sdxl:checkpoint:civitai:827184@2514310 interchangeably. Use the full urn:air:... form in API requests; it's the unambiguous canonical form.

Fields

Field	Required	Description
ecosystem	Optional	Model family bucket: sd15, sdxl, sd3, flux1, other, etc.
type	Optional	Resource kind: checkpoint, lora, embedding, vae, controlnet, upscaler.
source	Required	Hosting system: civitai, civitai-r2, huggingface, orchestrator.
id	Required	Resource identifier within the source. For civitai, this is the model ID.
version	Optional	Specific version (for civitai this is the model version ID). If omitted, the resource's default/latest version is implied.
fileId	Optional	Specific ModelFile id, prefixed with +. Disambiguates between multiple files attached to the same version (e.g. a pruned vs. full-weight checkpoint, or a base model shipped alongside its text-encoder file). Omit to let the resolver pick the primary file.
format	Optional	Model file format, e.g. safetensor, ckpt, diffuser.

Real examples

From actual GET /api/v1/model-versions/{id} responses and internal workflow templates:

urn:air:sdxl:checkpoint:civitai:827184@2514310
urn:air:sdxl:checkpoint:civitai:827184@2514310+2402203
urn:air:illustrious:checkpoint:civitai:795765@900661
urn:air:other:upscaler:civitai:147759@164821
urn:air:other:other:civitai-r2:civitai-worker-assets@sam_vit_b_01ec64.pth

The second example pins the AIR to a specific file on the version (e.g. waiIllustriousSDXL_v160.safetensors, file id 2402203) — useful when a version ships multiple downloadable artifacts and you need to be explicit about which one to load. The last one is a file asset (SAM ViT-B checkpoint) stored on Civitai's R2 bucket rather than a model version.

Type values

The type segment maps to Civitai's ModelType enum:

AIR type	Civitai ModelType
checkpoint	Checkpoint
lora	LORA
embedding	TextualInversion
vae	VAE
controlnet	Controlnet
upscaler	Upscaler

Resources that don't map to one of those (motion modules, detection models, wildcards, etc.) use other as the type.

Using AIR with the Orchestration API

The Orchestration API accepts AIR strings anywhere a resource is referenced. Given a modelVersionId from the site API, the simplest way to get a valid AIR is to call GET /api/v1/model-versions/{id} and forward the air field.

For example, to use WAI-illustrious-SDXL v16.0 in a text-to-image workflow:

1. curl https://civitai.com/api/v1/model-versions/2514310 → "air": "urn:air:sdxl:checkpoint:civitai:827184@2514310"
2. Pass that string as the checkpoint reference in your Orchestration submission.

Building an AIR by hand

You can also construct an AIR directly from a Civitai model version:

urn:air:{baseModel}:{type}:civitai:{modelId}@{versionId}[+{fileId}]

Where baseModel comes from the model version's baseModel field (SDXL 1.0 → sdxl, SD 1.5 → sd15, etc.) and type maps from the parent model's type field as shown in the table above. Append +{fileId} (using a ModelFile.id from files[] on the model version response) only when you need to pin a specific file; otherwise the resolver picks the primary file.

The site-generated air field already handles this mapping — prefer it over hand-construction when you have the option.