> ## Documentation Index > Fetch the complete documentation index at: https://api-reference.hyperswitch.io/llms.txt > Use this file to discover all available pages before exploring further. # Legacy Decision Gateway > Legacy compatibility route. New integrations should use /decide-gateway. ## OpenAPI ````yaml decision_engine_openapi-specs.json POST /decision_gateway openapi: 3.1.0 info: title: Decision Engine description: >- Open-source payment gateway routing service by Juspay. Selects the optimal payment processor for each transaction in real-time using success-rate scoring, rule-based routing, and elimination logic. ## Authentication This API supports two authentication methods: 1. **JWT Bearer Token** - For dashboard/user sessions - Header: `Authorization: Bearer ` - Obtain via `/auth/login` endpoint 2. **API Key** - For service-to-service/programmatic access - Header: `x-api-key: DE_<64_char_hex>` - Create via `/api-key/create` endpoint Protected endpoints require one of these authentication methods. version: 1.4.0 contact: name: Juspay url: https://github.com/juspay/decision-engine license: name: AGPL-3.0 url: https://www.gnu.org/licenses/agpl-3.0.html servers: - url: http://localhost:8080 description: Local development - url: https://sandbox.hyperswitch.io description: 'Hyperswitch sandbox with x-feature: decision-engine' security: [] tags: - name: Health description: Service liveness, readiness, and diagnostics - name: Auth description: Dashboard auth and merchant selection - name: API Keys description: Service-to-service API key management - name: Gateway Decision description: Core routing decision APIs - name: Score Feedback description: Feed transaction outcomes back to improve SR scoring - name: Merchant Account description: Merchant configuration management - name: Routing Rules description: Euclid declarative routing rules engine - name: Rule Configuration description: Service-level SR/elimination config - name: Config description: Routing key and dimension metadata - name: Analytics description: ClickHouse-backed analytics and audit reads - name: Compatibility description: Legacy compatibility routes - name: Connector Costs - name: Merchant Features - name: Autopilot paths: /decision_gateway: post: tags: - Compatibility summary: Legacy decision gateway description: Legacy compatibility route. New integrations should use /decide-gateway. operationId: legacyDecisionGateway requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/DecideGatewayRequest' responses: '200': description: Gateway decision result content: application/json: schema: $ref: '#/components/schemas/DecidedGateway' security: - BearerAuth: [] - ApiKeyAuth: [] components: schemas: DecideGatewayRequest: type: object required: - merchantId - paymentInfo - eligibleGatewayList - rankingAlgorithm properties: merchantId: type: string example: test_merchant paymentInfo: $ref: '#/components/schemas/PaymentInfo' eligibleGatewayList: type: array items: type: string example: - stripe - paypal - adyen rankingAlgorithm: type: string enum: - SR_BASED_ROUTING - PL_BASED_ROUTING - NTW_BASED_ROUTING - NTW_SR_HYBRID_ROUTING example: SR_BASED_ROUTING eliminationEnabled: type: boolean default: false enableMultiObjective: type: boolean description: >- Per-request override for the multi-objective (cost-aware) post-step. true forces it on, false forces it off; omitted falls back to the merchant's multi_objective_routing_enabled feature flag. DecidedGateway: type: object properties: decided_gateway: type: string example: stripe routing_approach: type: string example: SR_SELECTION_V3_ROUTING description: >- Routing approach used. SR_SELECTION_MULTI_OBJECTIVE indicates the multi-objective post-step promoted a cheaper gateway over the SR head. gateway_priority_map: type: object additionalProperties: type: number example: stripe: 0.94 adyen: 0.87 paypal: 0.72 routing_dimension: type: string routing_dimension_level: type: string reset_approach: type: string is_scheduled_outage: type: boolean is_rust_based_decider: type: boolean debit_routing_output: $ref: '#/components/schemas/DebitRoutingOutput' latency: type: number multi_objective_info: allOf: - $ref: '#/components/schemas/MultiObjectiveInfo' nullable: true description: >- Populated when the multi-objective post-step ran (multi_objective_routing_enabled feature flag or enableMultiObjective request field, outside hedging). Null otherwise. PaymentInfo: type: object required: - paymentId - amount - currency - paymentType - paymentMethodType - paymentMethod properties: paymentId: type: string example: pay_001 amount: type: number format: double example: 1000 currency: type: string description: ISO 4217 currency code. example: USD country: type: string nullable: true description: ISO 3166-1 alpha-2 country code. example: US customerId: type: string nullable: true example: cust_123 udfs: type: object nullable: true description: User-defined fields, keyed udf1..udf20. additionalProperties: type: string preferredGateway: type: string nullable: true description: Pins routing to a specific gateway when set. paymentType: type: string enum: - ORDER_PAYMENT - MANDATE_REGISTER - EMANDATE_REGISTER - MANDATE_PAYMENT - EMANDATE_PAYMENT - TPV_PAYMENT - TPV_EMANDATE_REGISTER - TPV_MANDATE_REGISTER - TPV_EMANDATE_PAYMENT - TPV_MANDATE_PAYMENT - PARTIAL_CAPTURE - PARTIAL_VOID - VAN_PAYMENT - MOTO_PAYMENT - UNKNOWN example: ORDER_PAYMENT metadata: type: string nullable: true internalMetadata: type: string nullable: true isEmi: type: boolean nullable: true emiBank: type: string nullable: true emiTenure: type: integer format: int32 nullable: true paymentMethodType: type: string description: >- Connector-defined payment method type, e.g. CARD, UPI, WALLET, NETBANKING. example: CARD paymentMethod: type: string description: Connector-defined payment method, e.g. CREDIT, DEBIT, GPAY. example: CREDIT paymentSource: type: string nullable: true authType: type: string nullable: true enum: - ATMPIN - THREE_DS - THREE_DS2 - OTP - OBO_OTP - VIES - NO_THREE_DS - NETWORK_TOKEN - MOTO - FIDO - CTP example: THREE_DS cardIssuerBankName: type: string nullable: true cardIsin: type: string nullable: true example: '411111' cardType: type: string nullable: true description: e.g. CREDIT, DEBIT, PREPAID, UPI, NB. example: CREDIT cardSwitchProvider: type: string nullable: true cardProgram: type: string nullable: true cardIssuerCountry: type: string nullable: true channel: type: string nullable: true description: 'Acceptance channel: ecom / pos / contactless.' DebitRoutingOutput: type: object properties: co_badged_card_networks_info: type: array items: type: object properties: network: type: string example: NYCE saving_percentage: type: number example: 1.2 issuer_country: type: string example: US is_regulated: type: boolean example: false regulated_name: type: string nullable: true card_type: type: string example: Debit MultiObjectiveInfo: type: object description: >- Present when the multi-objective (cost-aware) post-step ran. Explains why the gateway was picked: the SR head was kept (AUTH_WON) or a higher economic-value PSP was promoted (COST_WON). Economic value is auth rate × settlement value, where settlement value = txn amount − cost of payment processing (acquirer, issuer & network fee). properties: outcome: type: string enum: - COST_WON - AUTH_WON example: COST_WON reason: type: string example: >- Promoted 'adyen' over 'stripe' on expected value — saves 80.00 bps for 3.00pp auth. srHead: allOf: - $ref: '#/components/schemas/PspSummary' nullable: true description: The PSP the SR scorer would have picked. chosen: allOf: - $ref: '#/components/schemas/PspSummary' nullable: true description: The PSP the post-step actually chose. Equals srHead when auth won. costSavedBps: type: number nullable: true description: >- Fee saved in bps when outcome is COST_WON (srHead.costBps - chosen.costBps). example: 80 qualifiedCount: type: integer description: Number of PSPs that had cost data and were ranked on expected value. example: 3 margin: type: number description: >- Merchant margin (fraction of ticket) applied for this transaction. Configured via the successRate config margin field; defaults to 1.0. example: 0.2 evGapTop2: type: number nullable: true description: >- Expected-value gap between the top-two EV-ranked PSPs, as a fraction of ticket. Null when fewer than two PSPs had cost data. example: 0.00182 PspSummary: type: object properties: psp: type: string example: adyen authRate: type: number example: 0.91 costBps: type: number nullable: true example: 100 securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: JWT description: JWT token obtained from /auth/login ApiKeyAuth: type: apiKey in: header name: x-api-key description: API key created via /api-key/create ````