> ## Documentation Index > Fetch the complete documentation index at: https://docs.services.payward.com/llms.txt > Use this file to discover all available pages before exploring further. # Create Ramp checkout session > Creates a Ramp checkout for a selected user and returns the widget redirect URL with the checkout UUID in the fragment. No access token is minted here; the widget mints it via the bootstrap call (`BootstrapRampCheckout`). The URL must still be treated as sensitive — the UUID is a capability handle. ## OpenAPI ````yaml /api-reference/openapi_v3_pws.json post /v1/users/{user_id}/ramp/checkouts openapi: 3.1.0 info: title: Payward Services API description: >- The Payward Services (PWS) public API. PWS exposes Swaps (institutional FX-style trading), Conversions (rule-driven and one-shot fiat ↔ crypto value movement), retail-style Quotes and Price Trigger Swaps, end-user Users / Verifications, Funds (deposits, withdrawals, addresses, transactions), Portfolio, Earn, Reports, Webhooks, and Ramp (hosted fiat-to-crypto on-ramp checkout). All requests must be authenticated. All monetary values are decimal strings; all timestamps are ISO 8601 UTC. List endpoints are cursor-paginated. Errors follow a uniform shape (see `*ErrorResponse` schemas). version: v1 contact: name: Payward Services API Support url: https://docs.payward.com email: api-support@payward.com servers: - url: https://api.services.payward.com description: Production security: - ApiKey: [] ApiNonce: [] ApiSign: [] tags: - name: Users description: >- Users and headless-user onboarding flows that the partner manages. - **Create User** provisions a user with full identity verification fields collected up front. - **Create Headless User** provisions a lightweight user when your licensing agreement allows you to manage KYC data outside Payward. - **Get User** retrieves the user's profile, verification status, and required actions. - **Update User** updates user profile fields and may re-trigger verification. Use the returned user `id` for calls that require the user's identifier. - name: Assets description: >- Catalog of assets available on the platform with retail-display metadata (logos, market data, descriptions). - name: Conversions description: >- Rule-driven and one-shot fiat ↔ crypto value movement, including conversion rules, deposits, and whitelisted wallets. - name: Earn description: >- Manage auto-earn preferences and retrieve allocation and reward information. - name: Funds description: >- Deposits, withdrawals, addresses, methods, and the consolidated funding-transactions ledger. - name: Portfolio description: End-user portfolio summary, history, and transaction views. - name: Price Trigger Swaps description: Limit-style orders that execute when a configured price trigger is met. - name: On-chain Swaps description: >- Wallet-funded onchain quote trading for xStock and USDC pairs. On-chain quotes settle on-chain through the Payward on-chain proxy contract. - name: Ramp description: >- Hosted fiat-to-crypto on-ramp checkout: country / fiat / payment-method / cryptocurrency-asset discovery, transaction limits and prospective quotes, and the hosted checkout URL. - name: Reports description: Settlement and reconciliation reports for the partner. - name: Swaps description: >- Direct partner-to-Payward swap quotes and executions (institutional FX-style trading). - name: Verifications description: Identity verification (KYC) submission and status for end users. - name: Webhooks description: Manage webhook subscriptions for asynchronous event delivery. paths: /v1/users/{user_id}/ramp/checkouts: post: tags: - Ramp summary: Create Ramp checkout session description: >- Creates a Ramp checkout for a selected user and returns the widget redirect URL with the checkout UUID in the fragment. No access token is minted here; the widget mints it via the bootstrap call (`BootstrapRampCheckout`). The URL must still be treated as sensitive — the UUID is a capability handle. operationId: createRampCheckoutSession parameters: - in: path name: user_id required: true schema: type: string minLength: 14 maxLength: 42 x-selected-account: true style: simple description: >- ID of the user the checkout acts on behalf of. This is the user's IIBAN-derived public identifier. example: AA23N84GGQN4WE6I - in: header name: Idempotency-Key schema: type: string minLength: 1 maxLength: 128 style: simple description: >- Client-generated key for safe retries. Sent as the `Idempotency-Key` HTTP header. example: 550e8400-e29b-41d4-a716-446655440000 requestBody: content: application/json: schema: description: >- Request to create a token-bound Ramp checkout session. The `from`/`to` pairing determines the Ramp direction. Only on-ramp (`from` fiat, `to` crypto or stablecoin) is currently supported; other pairings are rejected with `400 BadRequest`. type: object properties: from: description: Source side of the checkout — the asset the user pays with. type: object properties: symbol: description: >- Asset ticker symbol (e.g. "USD"). Required. Use `GET /v1/ramp/fiat-currencies` to discover supported source currencies. type: string minLength: 3 maxLength: 16 type: description: >- Classification of the asset. Pair with `symbol` to disambiguate when the same ticker exists across asset classes (e.g. `USDC` as `stablecoin` vs `crypto`). Defaults to `fiat`. Only fiat sources are currently supported (on-ramp). type: string enum: - fiat - crypto - xstock - stablecoin - equity method: description: >- Funding method used for the source side. Required. Use `GET /v1/ramp/payment-methods` to discover supported payment methods. type: string minLength: 1 maxLength: 128 amount: description: >- Amount to spend, denominated in the source asset, as a decimal string. Required. type: string pattern: ^[0-9]+(\.[0-9]+)?$ minLength: 1 maxLength: 64 to: description: >- Destination side of the checkout — the asset the user receives. type: object properties: symbol: description: >- Asset ticker symbol (e.g. "BTC"). Required. Use `GET /v1/ramp/buy/crypto` to discover supported destination assets. type: string minLength: 3 maxLength: 16 type: description: >- Classification of the asset. Pair with `symbol` to disambiguate when the same ticker exists across asset classes (e.g. `USDC` as `stablecoin` vs `crypto`). Defaults to `crypto`. Only crypto and stablecoin destinations are currently supported (on-ramp). type: string enum: - fiat - crypto - xstock - stablecoin - equity method: description: >- Withdrawal method for the destination asset. Required. Use `GET /v1/ramp/buy/crypto` to discover available withdrawal methods for each asset. type: string minLength: 1 maxLength: 128 network: description: >- Optional withdrawal network identifier. Use `GET /v1/ramp/buy/crypto` to discover available networks for each destination asset. type: string minLength: 1 maxLength: 128 address: description: >- Optional destination wallet address for the crypto withdrawal. type: string minLength: 1 maxLength: 512 memo: description: >- Optional memo/tag/note for the crypto withdrawal (used for certain assets). type: string minLength: 1 maxLength: 256 affiliate_fee_bps: description: >- Affiliate fee in basis points to attribute to the partner (0-10000 where 100 = 1%). type: string pattern: ^(10000|[0-9]{1,4})$ minLength: 1 maxLength: 5 country: description: >- ISO 3166-1 alpha-2 country code. Use `GET /v1/ramp/countries` to discover supported values. type: string pattern: ^[A-Za-z]{2}$ minLength: 2 maxLength: 2 subdivision: description: >- ISO 3166-2 subdivision code suffix (e.g., `CA` for California when country is `US`). Use `GET /v1/ramp/countries` to discover supported values. type: string pattern: ^[A-Za-z0-9-]+$ minLength: 1 maxLength: 64 redirect_url: description: >- URL to redirect the user after completing checkout successfully. type: string minLength: 1 maxLength: 255 failure_url: description: URL to redirect the user after a failed checkout. type: string minLength: 1 maxLength: 255 external_user_id: description: Optional partner-supplied user identifier. type: string minLength: 1 maxLength: 64 external_partner_id: description: Optional partner-supplied partner identifier. type: string minLength: 1 maxLength: 64 external_transaction_id: description: Optional partner transaction identifier. type: string minLength: 1 maxLength: 64 external_metadata: description: Optional metadata to store alongside the checkout. type: string minLength: 1 maxLength: 1000 required: - from - to examples: createCheckout: summary: Create hosted checkout value: from: symbol: USD type: fiat method: credit_card amount: '100.00' to: symbol: BTC type: crypto method: Bitcoin network: Bitcoin address: bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh memo: '123456' affiliate_fee_bps: '250' country: US subdivision: CA redirect_url: https://example.com/checkout/success failure_url: https://example.com/checkout/failure external_user_id: user_01J0M7C0Z9F8YX3GQH8E external_partner_id: partner_456 external_transaction_id: INV-2026-04-0042 external_metadata: '{"order_id":"order_12345"}' required: true responses: '200': description: Successful response content: application/json: schema: type: object properties: data: description: Created checkout session details. type: object properties: checkout_id: description: Public checkout session identifier. type: string minLength: 36 maxLength: 36 checkout_url: description: >- Widget redirect URL with the checkout UUID in the fragment. No access token is present; the widget mints one via the bootstrap call. The UUID is a capability handle, so the URL is still sensitive. type: string minLength: 1 maxLength: 2048 expires_in: description: >- Checkout URL validity window, in seconds — how long the partner has to redirect the user before the handle should be considered stale. This is the creation-to-bootstrap window, not a token lifetime; the token TTL starts at bootstrap and is reported there. type: integer format: int64 request_data: description: Original request payload for client confirmation. type: object properties: from: description: Echo of the source (pay) side of the checkout. type: object properties: symbol: description: >- Asset ticker symbol (e.g. "USD"). Required. Use `GET /v1/ramp/fiat-currencies` to discover supported source currencies. type: string minLength: 3 maxLength: 16 type: description: >- Classification of the asset. Pair with `symbol` to disambiguate when the same ticker exists across asset classes (e.g. `USDC` as `stablecoin` vs `crypto`). Defaults to `fiat`. Only fiat sources are currently supported (on-ramp). type: string enum: - fiat - crypto - xstock - stablecoin - equity method: description: >- Funding method used for the source side. Required. Use `GET /v1/ramp/payment-methods` to discover supported payment methods. type: string minLength: 1 maxLength: 128 amount: description: >- Amount to spend, denominated in the source asset, as a decimal string. Required. type: string pattern: ^[0-9]+(\.[0-9]+)?$ minLength: 1 maxLength: 64 to: description: >- Echo of the destination (receive) side of the checkout. type: object properties: symbol: description: >- Asset ticker symbol (e.g. "BTC"). Required. Use `GET /v1/ramp/buy/crypto` to discover supported destination assets. type: string minLength: 3 maxLength: 16 type: description: >- Classification of the asset. Pair with `symbol` to disambiguate when the same ticker exists across asset classes (e.g. `USDC` as `stablecoin` vs `crypto`). Defaults to `crypto`. Only crypto and stablecoin destinations are currently supported (on-ramp). type: string enum: - fiat - crypto - xstock - stablecoin - equity method: description: >- Withdrawal method for the destination asset. Required. Use `GET /v1/ramp/buy/crypto` to discover available withdrawal methods for each asset. type: string minLength: 1 maxLength: 128 network: description: >- Optional withdrawal network identifier. Use `GET /v1/ramp/buy/crypto` to discover available networks for each destination asset. type: string minLength: 1 maxLength: 128 address: description: >- Optional destination wallet address for the crypto withdrawal. type: string minLength: 1 maxLength: 512 memo: description: >- Optional memo/tag/note for the crypto withdrawal (used for certain assets). type: string minLength: 1 maxLength: 256 affiliate_fee_bps: description: >- Affiliate fee in basis points (0-10000 where 100 = 1%). type: string pattern: ^(10000|[0-9]{1,4})$ minLength: 1 maxLength: 5 country: description: ISO 3166-1 alpha-2 country code type: string pattern: ^[A-Za-z]{2}$ minLength: 2 maxLength: 2 subdivision: description: >- ISO 3166-2 subdivision code suffix (e.g., CA for California when country is US) type: string pattern: ^[A-Za-z0-9-]+$ minLength: 1 maxLength: 64 redirect_url: description: >- URL where the ramp provider should redirect the user after successful checkout type: string minLength: 1 maxLength: 255 failure_url: description: >- URL where the ramp provider should redirect the user after failed checkout type: string minLength: 1 maxLength: 255 external_user_id: description: >- Partner-provided user identifier (max 64 characters) type: string minLength: 1 maxLength: 64 external_partner_id: description: >- Partner-provided partner identifier (max 64 characters) type: string minLength: 1 maxLength: 64 external_transaction_id: description: >- Partner-provided transaction identifier (max 64 characters) type: string minLength: 1 maxLength: 64 external_metadata: description: >- Additional partner-provided metadata (max 1000 characters) type: string minLength: 1 maxLength: 1000 required: - data examples: checkoutCreated: summary: Created hosted checkout value: data: checkout_id: 018fdb88-4a87-73b2-9b9f-b5f38d11b924 checkout_url: >- https://ramp.kraken.com/confirmation#checkout_id=018fdb88-4a87-73b2-9b9f-b5f38d11b924 expires_in: 600 request_data: from: symbol: USD type: fiat method: credit_card amount: '100.00' to: symbol: BTC type: crypto method: Bitcoin network: Bitcoin address: bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh memo: '123456' affiliate_fee_bps: '250' country: US subdivision: CA redirect_url: https://example.com/checkout/success failure_url: https://example.com/checkout/failure external_user_id: user_01J0M7C0Z9F8YX3GQH8E external_partner_id: partner_456 external_transaction_id: INV-2026-04-0042 external_metadata: '{"order_id":"order_12345"}' '400': description: Validation error content: application/json: schema: $ref: '#/components/schemas/BadRequestError' headers: Request-Id: $ref: '#/components/headers/RequestId' X-RateLimit-Limit: $ref: '#/components/headers/RateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/RateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/RateLimitReset' Strict-Transport-Security: $ref: '#/components/headers/StrictTransportSecurity' X-Content-Type-Options: $ref: '#/components/headers/XContentTypeOptions' Content-Security-Policy: $ref: '#/components/headers/ContentSecurityPolicy' Cache-Control: $ref: '#/components/headers/CacheControl' '401': description: Authentication required content: application/json: schema: $ref: '#/components/schemas/UnauthenticatedError' headers: Request-Id: $ref: '#/components/headers/RequestId' X-RateLimit-Limit: $ref: '#/components/headers/RateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/RateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/RateLimitReset' Strict-Transport-Security: $ref: '#/components/headers/StrictTransportSecurity' X-Content-Type-Options: $ref: '#/components/headers/XContentTypeOptions' Content-Security-Policy: $ref: '#/components/headers/ContentSecurityPolicy' Cache-Control: $ref: '#/components/headers/CacheControl' '403': description: Forbidden content: application/json: schema: $ref: '#/components/schemas/ForbiddenError' headers: Request-Id: $ref: '#/components/headers/RequestId' X-RateLimit-Limit: $ref: '#/components/headers/RateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/RateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/RateLimitReset' Strict-Transport-Security: $ref: '#/components/headers/StrictTransportSecurity' X-Content-Type-Options: $ref: '#/components/headers/XContentTypeOptions' Content-Security-Policy: $ref: '#/components/headers/ContentSecurityPolicy' Cache-Control: $ref: '#/components/headers/CacheControl' '429': description: Rate limit exceeded content: application/json: schema: $ref: '#/components/schemas/ResourceExhaustedError' headers: Request-Id: $ref: '#/components/headers/RequestId' X-RateLimit-Limit: $ref: '#/components/headers/RateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/RateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/RateLimitReset' Strict-Transport-Security: $ref: '#/components/headers/StrictTransportSecurity' X-Content-Type-Options: $ref: '#/components/headers/XContentTypeOptions' Content-Security-Policy: $ref: '#/components/headers/ContentSecurityPolicy' Cache-Control: $ref: '#/components/headers/CacheControl' Retry-After: $ref: '#/components/headers/RetryAfter' '500': description: Internal server error content: application/json: schema: $ref: '#/components/schemas/InternalError' headers: Request-Id: $ref: '#/components/headers/RequestId' X-RateLimit-Limit: $ref: '#/components/headers/RateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/RateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/RateLimitReset' Strict-Transport-Security: $ref: '#/components/headers/StrictTransportSecurity' X-Content-Type-Options: $ref: '#/components/headers/XContentTypeOptions' Content-Security-Policy: $ref: '#/components/headers/ContentSecurityPolicy' Cache-Control: $ref: '#/components/headers/CacheControl' '501': description: Not implemented content: application/json: schema: $ref: '#/components/schemas/UnimplementedError' headers: Request-Id: $ref: '#/components/headers/RequestId' X-RateLimit-Limit: $ref: '#/components/headers/RateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/RateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/RateLimitReset' Strict-Transport-Security: $ref: '#/components/headers/StrictTransportSecurity' X-Content-Type-Options: $ref: '#/components/headers/XContentTypeOptions' Content-Security-Policy: $ref: '#/components/headers/ContentSecurityPolicy' Cache-Control: $ref: '#/components/headers/CacheControl' '503': description: Service unavailable content: application/json: schema: $ref: '#/components/schemas/UnavailableError' headers: Request-Id: $ref: '#/components/headers/RequestId' X-RateLimit-Limit: $ref: '#/components/headers/RateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/RateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/RateLimitReset' Strict-Transport-Security: $ref: '#/components/headers/StrictTransportSecurity' X-Content-Type-Options: $ref: '#/components/headers/XContentTypeOptions' Content-Security-Policy: $ref: '#/components/headers/ContentSecurityPolicy' Cache-Control: $ref: '#/components/headers/CacheControl' '504': description: Deadline exceeded content: application/json: schema: $ref: '#/components/schemas/DeadlineExceededError' headers: Request-Id: $ref: '#/components/headers/RequestId' X-RateLimit-Limit: $ref: '#/components/headers/RateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/RateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/RateLimitReset' Strict-Transport-Security: $ref: '#/components/headers/StrictTransportSecurity' X-Content-Type-Options: $ref: '#/components/headers/XContentTypeOptions' Content-Security-Policy: $ref: '#/components/headers/ContentSecurityPolicy' Cache-Control: $ref: '#/components/headers/CacheControl' security: - ApiKey: [] ApiNonce: [] ApiSign: [] components: schemas: BadRequestError: description: Request validation failed or the request could not be processed. allOf: - $ref: '#/components/schemas/PwsValidationErrorEnvelope' - type: object required: - error properties: error: allOf: - $ref: '#/components/schemas/PwsValidationError' - type: object required: - status - code properties: status: type: integer format: int32 enum: - 400 code: type: string enum: - bad_request UnauthenticatedError: description: Authentication credentials are missing, invalid, or not accepted. allOf: - $ref: '#/components/schemas/PwsGeneralErrorEnvelope' - type: object required: - error properties: error: allOf: - $ref: '#/components/schemas/PwsGeneralError' - type: object required: - status - code properties: status: type: integer format: int32 enum: - 401 code: type: string enum: - unauthenticated ForbiddenError: description: The authenticated caller is not allowed to perform this operation. allOf: - $ref: '#/components/schemas/PwsGeneralErrorEnvelope' - type: object required: - error properties: error: allOf: - $ref: '#/components/schemas/PwsGeneralError' - type: object required: - status - code properties: status: type: integer format: int32 enum: - 403 code: type: string enum: - forbidden ResourceExhaustedError: description: The request was rate limited or a resource quota was exhausted. allOf: - $ref: '#/components/schemas/PwsGeneralErrorEnvelope' - type: object required: - error properties: error: allOf: - $ref: '#/components/schemas/PwsGeneralError' - type: object required: - status - code properties: status: type: integer format: int32 enum: - 429 code: type: string enum: - resource_exhausted InternalError: description: An unexpected server-side error occurred. allOf: - $ref: '#/components/schemas/PwsGeneralErrorEnvelope' - type: object required: - error properties: error: allOf: - $ref: '#/components/schemas/PwsGeneralError' - type: object required: - status - code properties: status: type: integer format: int32 enum: - 500 code: type: string enum: - internal UnimplementedError: description: The operation is not implemented by the upstream service. allOf: - $ref: '#/components/schemas/PwsGeneralErrorEnvelope' - type: object required: - error properties: error: allOf: - $ref: '#/components/schemas/PwsGeneralError' - type: object required: - status - code properties: status: type: integer format: int32 enum: - 501 code: type: string enum: - unimplemented UnavailableError: description: The service is temporarily unavailable. allOf: - $ref: '#/components/schemas/PwsGeneralErrorEnvelope' - type: object required: - error properties: error: allOf: - $ref: '#/components/schemas/PwsGeneralError' - type: object required: - status - code properties: status: type: integer format: int32 enum: - 503 code: type: string enum: - unavailable DeadlineExceededError: description: The upstream service did not complete the request before the deadline. allOf: - $ref: '#/components/schemas/PwsGeneralErrorEnvelope' - type: object required: - error properties: error: allOf: - $ref: '#/components/schemas/PwsGeneralError' - type: object required: - status - code properties: status: type: integer format: int32 enum: - 504 code: type: string enum: - deadline_exceeded PwsValidationErrorEnvelope: description: Error envelope for request validation failures. type: object required: - error properties: error: $ref: '#/components/schemas/PwsValidationError' PwsValidationError: description: Standard PWS API error object for request validation failures. type: object required: - type - status - instance - code properties: type: description: Machine-readable error class. type: string status: description: HTTP status code returned for this error. type: integer format: int32 instance: description: Request identifier for this specific error occurrence. type: string code: description: Stable machine-readable error code. type: string doc_url: description: Optional link to documentation for this error. type: string format: uri causes: description: Validation failures that contributed to the error. type: array items: $ref: '#/components/schemas/PwsErrorCause' PwsGeneralErrorEnvelope: description: Error envelope for operational or domain failures. type: object required: - error properties: error: $ref: '#/components/schemas/PwsGeneralError' PwsGeneralError: description: Standard PWS API error object for non-validation failures. allOf: - $ref: '#/components/schemas/PwsErrorBase' - type: object properties: causes: description: Additional error details, when present. type: array items: type: object additionalProperties: true PwsErrorCause: description: A single request validation failure. type: object required: - field - message properties: field: description: Dot-notation path to the offending request field. type: string message: description: Human-readable explanation of the failed validation rule. type: string PwsErrorBase: description: Common fields present on every PWS API error object. type: object required: - type - status - instance - code properties: type: description: Machine-readable error class. type: string status: description: HTTP status code returned for this error. type: integer format: int32 instance: description: Request identifier for this specific error occurrence. type: string code: description: Stable machine-readable error code. type: string doc_url: description: Optional link to documentation for this error. type: string format: uri headers: RequestId: description: >- Unique identifier for tracing this request across services. Include in support tickets. schema: type: string format: uuid example: 5f4d2a8e-91a4-4d6c-8a17-9b1e2c3f4a5b RateLimitLimit: description: Total requests allowed in the current window. schema: type: integer example: 1000 RateLimitRemaining: description: Requests remaining in the current window. schema: type: integer example: 955 RateLimitReset: description: Unix timestamp (seconds) when the rate-limit window resets. schema: type: integer format: int64 example: 1713182400 StrictTransportSecurity: description: >- Enforces HTTPS for the configured period. Always `max-age=63072000; includeSubDomains; preload`. schema: type: string example: max-age=63072000; includeSubDomains; preload XContentTypeOptions: description: Disables MIME sniffing. Always `nosniff`. schema: type: string enum: - nosniff example: nosniff ContentSecurityPolicy: description: >- Prevents embedding and resource loading. Always `default-src 'none'; frame-ancestors 'none'`. schema: type: string example: default-src 'none'; frame-ancestors 'none' CacheControl: description: Prevents caching of sensitive financial data. Always `no-store`. schema: type: string enum: - no-store example: no-store RetryAfter: description: Seconds the client should wait before retrying. schema: type: integer example: 30 securitySchemes: ApiKey: type: apiKey name: API-Key in: header description: Your public API key. Identifies the partner making the request. ApiNonce: type: apiKey name: API-Nonce in: header description: Monotonically increasing nonce included in the request signature. ApiSign: type: apiKey name: API-Sign in: header description: HMAC signature over the request, computed with your private key. ````