Phala Cloud Documentation — Confidential AI on TEE

Zero data retention (ZDR) means the upstream serving route that handles your request does not keep the prompt or completion after returning it. Use it when a prompt carries data you cannot leave on a third party’s disk. Two API surfaces implement ZDR:

GET /v1/models?zdr=true lists the models a ZDR request can reach.
provider: {"zdr": true} in a request body restricts routing for that request.

The two agree by construction. A model listed under ?zdr=true is one that provider: {"zdr": true} can route.

Route a request under zero data retention

Add the provider block to a chat completion request:

curl https://inference.phala.com/v1/chat/completions \
  -H "Authorization: Bearer <API_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "<MODEL_ID>",
    "messages": [{"role": "user", "content": "Summarize this contract clause."}],
    "provider": {"zdr": true}
  }'

If no route for that model operates under zero data retention, the request fails before the prompt is sent:

{
  "error": {
    "message": "No zero-data-retention providers are available for the selected model.",
    "type": "not_found_error"
  }
}

The status is 404. This is a fail-closed check: the gateway does not fall back to a non-ZDR route, and failover retries stay inside the ZDR set. Setting "zdr": false, or omitting the field, applies no retention constraint and behaves like a request with no provider block.

List models you can use

curl -s "https://inference.phala.com/v1/models?zdr=true" \
  -H "Authorization: Bearer <API_KEY>" \
  | jq -r '.data[].id'

Embedding models have their own catalog, which takes the same parameter:

curl -s "https://inference.phala.com/v1/embeddings/models?zdr=true" \
  -H "Authorization: Bearer <API_KEY>" \
  | jq -r '.data[].id'

true is the only accepted value. Any other value, including false, returns 400. Omit the parameter for the full catalog. Rejecting other values is deliberate: a typo cannot silently return an unfiltered list that looks filtered. A model object has no zdr field. The filter is how you read this property, so query the filtered catalog rather than inspecting individual model objects.

ZDR is different from confidential inference

These are different properties and you may need either, or both.

	What it constrains	How to select it	How to verify it
Confidential inference (`is_tee`)	Who can read memory while the model runs. The upstream is attested and the channel is bound before the prompt is sent.	`is_tee: true` on a model object	The per-response receipt records `upstream.verified.result`.
Zero data retention (`zdr`)	Whether the upstream stores prompt and completion content after serving.	`?zdr=true`, `provider: {"zdr": true}`	Provider contract and published policy.

The distinction matters because a TEE constrains execution, not storage. A provider could run a model inside an enclave and still write request logs to disk.

Do not infer ZDR from is_tee. Filter with ?zdr=true when you need the retention property, and route with provider: {"zdr": true} when a specific request must stay inside the ZDR set.

Zero data retention is a property of the upstream serving route, backed by its contract or published policy. It is not proven by the attestation report or the receipt, which cover workload identity and response integrity. Confidential inference is the property the receipt proves. See Verify a Response.

Gateway retention

The gateway does not store request or response bodies for ZDR or non-ZDR requests. Receipts hold hashes and verification facts, not content. See Trust Boundary. Setting zdr changes which upstream route serves the request. It does not change gateway behavior.

List Models

The zdr query parameter and model object fields.

Chat Completions

The provider routing block.

Provider Verification

How upstream serving environments are verified.

Compliance and Open Source

How retention maps to compliance requirements.

​Route a request under zero data retention

​List models you can use

​ZDR is different from confidential inference

​Gateway retention

​Related

List Models

Chat Completions

Provider Verification

Compliance and Open Source

Route a request under zero data retention

List models you can use

ZDR is different from confidential inference

Gateway retention

Related