---
title: "Preflight - prompt quality + endpoint trust check ($0.05 USDC)"
method: POST
path: "/api/preflight"
tags: ["preflight", "paid", "evm"]
---

# Preflight - prompt quality + endpoint trust check ($0.05 USDC)

`POST /api/preflight`

## Request

- Base URL: `https://promptqualityscore.com`
- URL: `https://promptqualityscore.com/api/preflight`
- Auth: one of:
  - API key in header `X-PAYMENT`
  - API key in header `Authorization`

Combined PQS prompt quality + x402 endpoint trust check before inference

## Request body

- object
  - `prompt` string, required: Prompt to preflight
  - `vertical` 'software' | 'content' | 'business' | 'education' | 'science' | 'crypto' | 'general' | 'research': Domain: software/content/business/education/science/crypto/general/research
  - `endpoint_url` string: Optional endpoint URL for trust scoring

## Response `200`

Scoring result

- object
  - `pqs_version` '2.0', required
  - `chain` 'base' | 'solana'
  - `clearance` 'CLEAR' | 'CAUTION' | 'BLOCK', required
  - `confidence` number
  - `prompt` object, required
    - `score` integer
    - `out_of` 80
    - `grade` string
    - `threshold_met` boolean
    - `top_issue` string, nullable
    - `dimensions` object
      - `clarity` integer
      - `specificity` integer
      - `context` integer
      - `constraints` integer
      - `output_format` integer
      - `role_definition` integer
      - `examples` integer
      - `cot_structure` integer
      - `total` integer
    - `feedback` string[]
  - `endpoint` object: Present only when endpoint_url was supplied
    - `wallet` string
    - `trust_score` number
    - `trust_label` string
    - `resolution_source` string

## Other responses

- `400`: Invalid request body
- `401`: Invalid or missing bearer API key (when using bearer auth)
- `402`: Payment Required - x402 challenge when no bearer API key present. See x-payment-info.

---

[API](https://skmtc.dev/promptqualityscore/apis/pqs-prompt-quality-score.md) · [All operations](https://skmtc.dev/promptqualityscore/apis/pqs-prompt-quality-score/llms.txt) · [OpenAPI document](https://skmtc.dev/promptqualityscore/apis/pqs-prompt-quality-score/revisions/7f3f43a1c864?raw)