> ## Documentation Index > Fetch the complete documentation index at: https://docs.suby.fi/llms.txt > Use this file to discover all available pages before exploring further. # Price a fiat amount in a token > **Indicative.** The authoritative amount is the one frozen onto the charge when you create it. A quote fetched a minute earlier is a display value, and treating it as the amount due is how a volatile-asset payment lands short. There is no way to supply the token amount yourself: quoting is exactly where a caller-supplied number would let a payer decide what they owe. Volatile assets already carry their buffer in `tokenAmount`. ## OpenAPI ````yaml /v3-beta/api-reference/openapi.yaml get /v3/crypto/quote openapi: 3.1.0 info: title: Suby.fi Merchant API version: 3.0.0-beta description: > The **v3** public merchant API for Suby.fi. RESTful (plural, resource-oriented endpoints under the `/v3` prefix). Authenticate every request with your secret API key in the `X-Suby-Api-Key` header. - `sk_live_…` keys operate in **production** (real funds). - `sk_sandbox_…` keys operate in a fully simulated **sandbox** (test cards, Base Sepolia crypto, no real money). The environment is derived from the key prefix. contact: email: contact@suby.fi url: https://suby.fi servers: - url: https://api.beta.suby.fi description: Production + sandbox (environment selected by API key prefix) security: - ApiKeyAuth: [] tags: - name: Products description: Manage your product catalog (one-time and recurring). - name: Checkout description: >- Hosted checkout · signed session tokens (`cs_…`). Every card Suby holds was collected here, which is what keeps card data out of your systems. - name: Payments description: >- Read payments and receipts, refund them, and debit a stored instrument off-session (pay-as-you-go). Collecting a card happens on the hosted checkout, never here. - name: Subscriptions description: >- Drive a live subscription · read it, change its plan, end it. Subscriptions are opened by a checkout session, not by this API. - name: Discount Codes description: Promo codes, redeemed at checkout. - name: Crypto description: >- The headless rail · quote, charge, and settle on-chain from inside your own site. No card data is involved, so none of the constraints that keep card collection on a Suby page apply here. - name: Customers description: First-class customer records with billing address. - name: Payment Methods description: >- Read and detach the cards a customer has stored. They are created by a checkout session (`savePaymentMethod`, or `mode=setup`) · the only place a card is collected. - name: Licence Key description: >- The licence server · validate a key, take a seat, free one. Authenticated with your API key like everything else, and scoped to the licences you issued, so your backend relays the check rather than your customer's software calling it directly. paths: /v3/crypto/quote: get: tags: - Crypto summary: Price a fiat amount in a token description: > **Indicative.** The authoritative amount is the one frozen onto the charge when you create it. A quote fetched a minute earlier is a display value, and treating it as the amount due is how a volatile-asset payment lands short. There is no way to supply the token amount yourself: quoting is exactly where a caller-supplied number would let a payer decide what they owe. Volatile assets already carry their buffer in `tokenAmount`. operationId: getCryptoQuote parameters: - name: chainId in: query required: true schema: type: integer example: 8453 - name: asset in: query required: true description: The token's ticker on that chain, case-insensitive. schema: type: string example: ETH minLength: 2 maxLength: 12 - name: priceCents in: query required: true description: Minor units as a string of digits. schema: type: string pattern: ^[1-9]\d*$ example: '1999' - name: currency in: query required: true schema: type: string pattern: ^[A-Z]{3}$ responses: '200': description: Quote content: application/json: schema: allOf: - $ref: '#/components/schemas/SuccessEnvelope' - properties: data: $ref: '#/components/schemas/CryptoQuote' '401': $ref: '#/components/responses/Unauthorized' '422': description: >- The asset is not accepted, the currency is not supported, or the price feed cannot quote the pair right now. content: application/json: schema: $ref: '#/components/schemas/Error' components: schemas: SuccessEnvelope: type: object required: - success - data properties: success: type: boolean example: true message: type: string data: description: Endpoint-specific payload. CryptoQuote: type: object properties: chainId: type: integer asset: type: string example: ETH description: Echoed back, normalised uppercase. decimals: type: integer isStable: type: boolean tokenAmount: type: string description: Smallest unit (wei / lamports / sats), volatility buffer applied. priceCents: type: string description: The fiat side this was priced from, echoed back. currency: type: string quotedAt: type: string format: date-time description: A volatile asset moves in minutes · this is how old the number is. Error: type: object required: - success - error properties: success: type: boolean example: false error: type: string description: Machine-readable error code. example: NOT_FOUND message: type: string example: Resource not found data: description: Optional error detail. responses: Unauthorized: description: Invalid or missing API key content: application/json: schema: $ref: '#/components/schemas/Error' example: success: false error: UNAUTHORIZED message: Invalid or missing API key securitySchemes: ApiKeyAuth: type: apiKey in: header name: X-Suby-Api-Key description: Secret API key. `sk_live_…` (production) or `sk_sandbox_…` (sandbox). ````