> ## Documentation Index > Fetch the complete documentation index at: https://agora402.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # HBAR/USD rate > Paid, per query. Returns the HBAR/USD rate the Hedera network itself uses for fees, read from the exchange rate file through the mirror node, with the consensus expiry of that rate. Priced per unit with unit "query", so the 402 always asks for exactly one unit; pass quoteId as a query parameter to pin a quote. A mirror node failure answers 502 and cancels settlement. This endpoint is paid. Read [Paying for a request](/api/paying-for-a-request) for the 402 handshake, or let `BuyerAgent.hbarRate()` handle it. ## OpenAPI ````yaml /openapi.yaml get /v1/rates/hbar openapi: 3.1.0 info: title: Agora402 seller API version: 1.0.0 description: >- HTTP API served by every Agora402 seller: free discovery documents, a free quote endpoint, and paid endpoints gated by x402 and settled on Hedera through the Blocky402 facilitator. Typical agent flow: getManifest (what is sold, at what price, paid to which account) -> requestQuote (lock a signed price, counter below list if you like) -> call the paid endpoint with the quoteId. The first call answers 402 with a PAYMENT-REQUIRED header; the retry carries PAYMENT-SIGNATURE; the response carries PAYMENT-RESPONSE with the Hedera transaction id. Then read listReceipts or the seller's HCS receipts topic to audit what was charged. All amounts are decimal strings in atomic units of the asset (tinybars for HBAR, 8 decimals); timestamps are ISO 8601 unless stated; quote expiry is unix seconds. servers: - url: http://localhost:4402 description: Local services seller (npm run dev) - url: http://localhost:4404 description: Local auditor (npm run dev) security: [] tags: - name: Discovery description: Free documents that describe the seller. Read these before paying anyone. - name: Negotiation description: Free, signed, time-limited price quotes. - name: Paid services description: x402-gated endpoints. Every call is a Hedera micropayment. - name: Trust description: Paid audits of other sellers, attested on the HCS audit topic. - name: Receipts description: What this seller has been paid for. paths: /v1/rates/hbar: get: tags: - Paid services summary: HBAR/USD rate description: >- Paid, per query. Returns the HBAR/USD rate the Hedera network itself uses for fees, read from the exchange rate file through the mirror node, with the consensus expiry of that rate. Priced per unit with unit "query", so the 402 always asks for exactly one unit; pass quoteId as a query parameter to pin a quote. A mirror node failure answers 502 and cancels settlement. operationId: getHbarRate parameters: - name: quoteId in: query required: false schema: type: string description: >- Quote to pin the price to, from requestQuote with endpointId hbar-rate. - $ref: '#/components/parameters/PaymentSignature' responses: '200': description: Current rate headers: PAYMENT-RESPONSE: $ref: '#/components/headers/PaymentResponse' x-agora-usage: schema: type: string description: Always {"units":1,"unit":"query"}. content: application/json: schema: $ref: '#/components/schemas/RateResponse' example: pair: HBAR/USD usdPerHbar: 0.0627 centsPerHbar: 6.27 source: hedera network exchange rate file via mirror node expirationTime: 1789563600 fetchedAt: '2026-09-13T12:34:56.789Z' agora: seller: >- uaid:aid:2NEpo7TZRRrLZSi2U;uid=agora-demo-seller;registry=agora402;proto=a2a;nativeId=hedera:testnet:0.0.5001234;domain=localhost:4402 '402': $ref: '#/components/responses/PaymentRequired' '502': description: >- Mirror node unavailable. Settlement is cancelled; nothing is charged. content: application/json: schema: $ref: '#/components/schemas/Error' example: error: rate source unavailable components: parameters: PaymentSignature: name: PAYMENT-SIGNATURE in: header required: false schema: type: string description: >- x402 payment payload (base64 JSON) built from the PAYMENT-REQUIRED challenge of the 402 answer. Omit on the first call to receive the price. BuyerAgent and @x402/fetch set this for you. The legacy name X-PAYMENT is also accepted. headers: PaymentResponse: schema: type: string description: >- x402 settlement result (base64 JSON) including the Hedera transaction id, e.g. 0.0.4009876@1789560131.552341000. Look it up on HashScan or through the mirror node. schemas: RateResponse: type: object required: - pair - usdPerHbar - centsPerHbar - source - expirationTime - fetchedAt - agora properties: pair: type: string enum: - HBAR/USD usdPerHbar: type: number description: centsPerHbar / 100 centsPerHbar: type: number description: >- cent_equivalent / hbar_equivalent from the network exchange rate file source: type: string expirationTime: type: integer description: Unix seconds at which the network rate expires fetchedAt: type: string format: date-time agora: type: object properties: seller: $ref: '#/components/schemas/Uaid' Error: type: object required: - error properties: error: type: string description: Human-readable reason detail: type: string Uaid: type: string pattern: '^uaid:' description: HCS-14 universal agent id example: >- uaid:aid:2NEpo7TZRRrLZSi2U;uid=agora-demo-seller;registry=agora402;proto=a2a;nativeId=hedera:testnet:0.0.5001234;domain=localhost:4402 PaymentRequiredBody: type: object required: - error - endpoint - hint - quoteId properties: error: type: string enum: - payment required endpoint: type: string description: endpointId of the resource hint: type: string quoteId: type: - string - 'null' description: The quoteId you sent, if any responses: PaymentRequired: description: >- No valid payment attached. The PAYMENT-REQUIRED header carries the x402 challenge (scheme exact, network, asset, amount, payTo, facilitator). Build the payment, retry with PAYMENT-SIGNATURE. headers: PAYMENT-REQUIRED: schema: type: string description: >- base64 JSON x402 challenge with the accepted payment options for this exact request content: application/json: schema: $ref: '#/components/schemas/PaymentRequiredBody' example: error: payment required endpoint: infer hint: >- POST /a2a/quote with {"endpointId":"infer"} to negotiate, then retry with the quoteId quoteId: null ````