# Delx Commerce — Accept Header Rank

> Delx Commerce — Accept Header Rank is a paid API for AI agents from commerce.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).

Ranks a list of MIME type offers against an HTTP Accept header and returns the best match according to quality weighting

## Facts

- Endpoint: POST https://commerce.delx.ai/api/v1/x402/accept-header-rank?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-commerce-accept-header-rank-2864eae5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_EtVFK9W3CyyjckQRNII93

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability delx-commerce-accept-header-rank-2864eae5 -d '<json body>'
```

Example prompt: Given the Accept header 'text/html,application/xhtml+xml,application/json;q=0.9,*/*;q=0.8' and my server's available formats ['application/json','text/html','text/plain'], which content type should I respond with?

## When to prefer this

Choose this endpoint when you need a standards-compliant, verifiable, stateless computation of HTTP Accept header content negotiation — particularly in agent pipelines where auditability matters (evidenced by input hash and zero external calls guarantee). Prefer it over rolling your own parser when you need a pay-per-use, no-signup solution with cryptographic proof of non-retention. Ideal for agents that dynamically select response formats or validate their own content negotiation logic.

## Known failure modes

- Malformed Accept header string may produce unexpected rankings or errors
- Empty offers array results in no selection
- Offers exceeding 256 items are rejected by schema validation
- Header string exceeding 8192 characters rejected
- Payment failure via x402 protocol blocks the request
- Wildcard MIME types (*/*) may need careful interpretation in the ranked output

## How this service works

Pay-per-result APIs for agents. No signup. Exact price. Verifiable delivery. USDC on Base + Solana via x402.

## Output

Returns a JSON object containing a ranked array of offers each with their computed quality score, the single selected best-match offer, an operation identifier, a status of 'pass', and an evidence object including whether input was retained (always false), the SHA-256 hash of the input for verifiability, and the count of external calls made (always 0).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "header": {
   "type": "string",
   "maxLength": 8192,
   "description": "Header supplied to Accept Header Rank; used only for this bounded calculation and processed in memory without retention."
  },
  "offers": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Offers supplied to Accept Header Rank; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "ranked": [
    {
     "offer": "application/json",
     "quality": 1
    },
    {
     "offer": "text/plain",
     "quality": 0.5
    }
   ],
   "selected": "application/json"
  },
  "schema": "delx/util-accept-header-rank/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "6f60834b6ddd258ebac619ec48677f1ee272c525d95ebcd2374e0b3d4e7daba8",
   "external_calls": 0
  },
  "operation": "web_reliability:accept_header_rank"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-commerce-accept-header-rank-2864eae5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from commerce.delx.ai](https://www.zero.xyz/host/commerce.delx.ai/llms.txt)