Shopify product CSV release check: POST raw CSV text (up to 1,000 rows), get back a JSON report - duplicate SKUs, missing required fields (Title, Handle, Price, Variant SKU), malformed prices, bad handles, invalid image URLs, variant row problems, plus a cleaned/import-ready CSV. Deterministic, no signup.

GET /v1/csv-check costs $0.03 per call in USDC on Base, paid with the x402 protocol. Call it with any x402 client; an unpaid request returns HTTP 402 with the payment details.