# Vary Header Normalize

> Vary Header Normalize is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-19).

Normalizes and deduplicates HTTP Vary header field names from a caller-supplied header string, returning a cleaned canonical form with pass/advisory status.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/vary-header-normalize?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vary-header-normalize-13793a7c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_d4FKUuiBUOr6dgIhFGbpt

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 vary-header-normalize-13793a7c -d '<json body>'
```

Example prompt: Can you normalize and deduplicate this Vary header for me before I cache the response: 'Accept-Encoding, accept-encoding, Accept, User-Agent'?

## When to prefer this

Use this endpoint when you need a deterministic, stateless, zero-retention normalization of HTTP Vary headers before making caching, redirecting, or retrying decisions — especially in agentic pipelines where consistent cache-key computation depends on canonical header field names. Prefer it over manual string manipulation when deduplication and case-normalization correctness matter and you want an explicit pass/advisory audit trail.

## Known failure modes

- Header string exceeds 8192 character limit — request rejected
- Malformed or unparseable header value — advisory status returned with finding detail
- Empty header string — may return pass with empty normalized output
- Payment failure via x402 — request not processed

## How this service works

Vary Header Normalize: Vary Header Normalize normalizes and deduplicates Vary header field names from bounded caller-supplied values without an external provider. Call Vary Header Normalize before accepting, caching, redirecting, or retrying a caller-supplied web response. Returns normalized web evidence, the computed finding, and an explicit pass or advisory status for Vary Header Normalize as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base. First-party, stateless, memory-onl…

## Output

Returns versioned deterministic JSON containing the normalized Vary header field names (deduplicated and canonicalized), the computed finding describing what was changed or confirmed, and an explicit pass or advisory status indicating whether the header is acceptable for use in caching, redirecting, or retrying scenarios.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "header": {
   "type": "string",
   "maxLength": 8192,
   "description": "Header supplied to Vary Header Normalize; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "tokens": [
    "accept-encoding",
    "origin"
   ],
   "normalized": "accept-encoding, origin"
  },
  "schema": "delx/util-vary-header-normalize/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "939169b314b2600276b55d910c792908209d28331261b7f22bab533cf1e6cd07",
   "external_calls": 0
  },
  "operation": "web_reliability:vary_header_normalize"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vary-header-normalize-13793a7c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)