# Qty

> Deterministic quantity API. Free when the input is a finite number and two known unit codes. Paid exact USDC when the text is messy. No accounts, no invented numbers.

Qty converts and interprets quantities in code. It does not call a model. Payments are exact USDC on eip155:8453 payTo 0x41F7c3FfC3Cda926797Eb388bB65Ccd8A1deC352; solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp payTo GhBZyUbBH2qdTbUXtNjFnbiqeh9c7rsReVU6kjJVCbp6. Facilitator: https://facilitator.payai.network.

## Docs

- [OpenAPI](https://qty.vercel.app/openapi.json): Routes, prices, and schemas.
- [Full notes](https://qty.vercel.app/llms-full.txt): Formulas, error codes, and unit codes.
- [Human docs](https://qty.vercel.app/docs): Short guide.
- [x402 manifest](https://qty.vercel.app/.well-known/x402): Payable resource URLs.
- [Agent card](https://qty.vercel.app/.well-known/agent-card.json): A2A agent card.
- [MCP](https://qty.vercel.app/mcp): Streamable HTTP tools. convert and units are free. The other tools use the same x402 prices as HTTP.
- [OpenAI tools](https://qty.vercel.app/tools/openai.json): Function tools generated from the MCP schemas.
- [Anthropic tools](https://qty.vercel.app/tools/anthropic.json): Tool definitions for Claude, same schemas as MCP.
- [AI SDK example](https://qty.vercel.app/tools/ai-sdk.ts): Vercel AI SDK tools generated from the same schemas.
- [Prepaid credits](https://qty.vercel.app/docs/prepaid-credits): Design note. Qty does not store balances.

## Free

- [Health](https://qty.vercel.app/health): Liveness. No payment.
- [Units](https://qty.vercel.app/units): Unit codes, aliases, and definition ids.
- [Convert](https://qty.vercel.app/v1/convert): POST {value, from, to}. 60 requests per 60 seconds. Messy text returns use_parse.
- [Feed](https://qty.vercel.app/v1/feed): Recent sanitised conversions. Raw text is not stored.

## Paid

- [parse](https://qty.vercel.app/v1/parse): Interpret messy quantity text into a list of quantities. Call this when convert returns use_parse. Deterministic. Never invents a number: unknown amounts are null with a reason. Same text always returns the same quantities. Does not call a model or any other service. Price $0.002. Unpaid calls return 402.
- [batch](https://qty.vercel.app/v1/batch): Parse up to 100 messy texts for a flat price. One bad row does not fail the batch. Each row is ok with quantities or ok:false with a stable error code. Deterministic. No per-row upto pricing in v1. Price $0.01. Unpaid calls return 402.
- [receipt](https://qty.vercel.app/v1/receipt): Canonical audit JSON plus sha256 of a previous Qty result. Includes input, definition ids, formulas, and a timestamp. The hash ignores the timestamp so the same payload always hashes the same. No chain write. Price $0.001. Unpaid calls return 402.
- [compare-prices](https://qty.vercel.app/v1/compare-prices): Normalise unit prices and say which offer is cheaper. Currency is a label only; Qty never converts between currencies. Multipacks are totalled first. Returns price per base unit (litre, kilogram, or each). Price $0.002. Unpaid calls return 402.
- [scale-recipe](https://qty.vercel.app/v1/scale-recipe): Scale ingredient amounts by servings or a factor. Cup, tbsp, tsp, and stick convert between us, imperial, and si using the labelled assumption table. Mass and volume convert only for flour, sugar, butter, water, milk, and rice. Anything else is null with a reason. Price $0.002. Unpaid calls return 402.
- [size](https://qty.vercel.app/v1/size): Convert shoe and clothing sizes using Qty size table v1. Men's UK 9 shoe is EU 43 and US 10. Ambiguous gender or category returns null and a reason. Brand variance is always a warning. No interpolation. Price $0.002. Unpaid calls return 402.
- [date](https://qty.vercel.app/v1/date): Parse ISO-8601 durations, add N days from an explicit date, and convert IANA time zones. Working days skip Saturday and Sunday plus an optional caller holiday list. Daylight-saving gaps and overlaps are reported. There is no built-in holiday calendar. If the text needs a date and none was given, the value is null with a reason. Qty never uses the current clock. Price $0.002. Unpaid calls return 402.
- [estimate](https://qty.vercel.app/v1/estimate): Estimate paint, tiles, concrete, or gravel. Paint uses 10 m² per litre per coat and defaults to 2 coats. Tiles default to 0.30 m × 0.30 m. A 25 kg concrete bag yields 0.012 m³. Gravel uses 1600 kg/m³. Waste defaults to 10 percent and is stated on the result. Assumptions are labels, not a quote from a supplier. Price $0.003. Unpaid calls return 402.