> ## Documentation Index > Fetch the complete documentation index at: https://lava.so/docs/llms.txt > Use this file to discover all available pages before exploring further. # Forward GET request > Forward a GET request to a third-party API (like OpenAI, Anthropic, etc.) with usage tracking and billing. ## OpenAPI ````yaml /openapi.json get /forward openapi: 3.0.0 info: title: Lava API description: >- Lava API enables businesses to implement usage-based billing for AI services. This API allows tracking, managing, and billing for third-party AI API usage through a forwarding system. version: 1.0.0 contact: name: Lava support url: https://www.lava.so/contact servers: - url: https://api.lava.so/v1/ description: Lava API v1 security: [] tags: - name: Authentication - name: Core Endpoints - name: Models - name: Services - name: Requests - name: Wallet - name: Payment Methods - name: Spend Keys - name: Usage - name: Checkout Sessions - name: Customers - name: Plans - name: Subscriptions - name: Meters - name: Webhooks - name: Secret Keys - name: Credit Bundles - name: Gateway Settings - name: Skills - name: News Data - name: Search - name: Enrich paths: /forward: get: tags: - Core Endpoints summary: Forward GET request description: >- Forward a GET request to a third-party API (like OpenAI, Anthropic, etc.) with usage tracking and billing. parameters: - name: u in: query required: true schema: type: string example: https://api.openai.com/v1/models description: The API endpoint URL to forward the request to responses: '200': description: Successful response from the provider API content: application/json: schema: type: object description: Response from the provider API additionalProperties: true examples: models-response: summary: Example response from /v1/models endpoint value: object: list data: - id: gpt-4-1106-preview object: model created: 1699066192 owned_by: openai - id: gpt-3.5-turbo object: model created: 1677610602 owned_by: openai '400': description: Bad request content: application/json: schema: $ref: '#/components/schemas/Error' examples: forward_url_missing: summary: URL parameter is missing value: error: message: >- URL parameter is missing. Please include the target URL using the ?u= query parameter. code: forward_url_missing status: 400 forward_endpoint_not_supported: summary: Endpoint not supported value: error: message: >- This endpoint is not supported. Please refer to our documentation for a list of available endpoints. code: forward_endpoint_not_supported status: 400 '401': description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/Error' examples: forward_token_missing: summary: Forward token missing value: error: message: >- Forward token is missing. Please provide your token using one of these methods: 'Authorization: Bearer ' header, 'x-api-key: ' header, 'key' query parameter, or 'x-goog-api-key: ' header. code: forward_token_missing status: 401 '402': description: Payment required content: application/json: schema: $ref: '#/components/schemas/Error' examples: forward_token_customer_limit_reached: summary: Customer usage limit reached value: error: message: >- Your customer has reached its usage limit. Please top up your credit balance to continue using this service. code: forward_token_customer_limit_reached status: 402 '500': description: Internal server error content: application/json: schema: $ref: '#/components/schemas/Error' examples: forward_request_failed: summary: Request forwarding failed value: error: message: >- Failed to forward your request to the target service. This may be due to network issues or the target service being unavailable. code: forward_request_failed status: 500 security: - ForwardAuth: [] - ForwardAuthAnthropic: [] - ForwardAuthGoogle: [] - ForwardAuthGoogleQueryParam: [] components: schemas: Error: type: object properties: error: type: object properties: message: type: string description: Human-readable error message describing what went wrong example: Invalid authentication credentials code: type: string description: Machine-readable error code describing what went wrong example: forward_token_json_invalid status: type: integer description: HTTP status code of the error example: 400 issues: type: array items: type: object properties: path: type: array items: type: string description: Path to the field that caused the validation error message: type: string description: Error message describing the validation issue required: - path - message description: >- Optional array of specific validation issues with their paths and messages example: - path: - model message: 'Missing required field: model' - path: - messages - '0' - content message: Invalid message content format required: - message - code - status required: - error securitySchemes: ForwardAuth: type: http scheme: bearer description: >- Special authentication used for the forward endpoint. Requires a base64-encoded JSON object containing secret_key, customer_id, and meter_slug. Optionally include provider_key to use your own API key for the request. When using your own API key, you can make requests that use metering only by setting both customer_id and meter_slug to null. Format: 'Bearer BASE64_ENCODED_JSON' ForwardAuthAnthropic: type: apiKey in: header name: x-api-key description: >- You can pass an x-api-key header to authenticate with the forward endpoint for compatibility with anthropic style clients. Requires a base64-encoded JSON object containing secret_key, customer_id, and meter_slug. Optionally include provider_key to use your own API key for the request. When using your own API key, you can make requests that use metering only by setting both customer_id and meter_slug to null. ForwardAuthGoogle: type: apiKey in: header name: x-goog-api-key description: >- You can pass an x-goog-api-key header to authenticate with the forward endpoint for compatibility with Google style clients. Requires a base64-encoded JSON object containing secret_key, customer_id, and meter_slug. Optionally include provider_key to use your own API key for the request. When using your own API key, you can make requests that use metering only by setting both customer_id and meter_slug to null. ForwardAuthGoogleQueryParam: type: apiKey in: query name: key description: >- You can pass a key query parameter to authenticate with the forward endpoint for compatibility with Google style clients. Requires a base64-encoded JSON object containing secret_key, customer_id, and meter_slug. Optionally include provider_key to use your own API key for the request. When using your own API key, you can make requests that use metering only by setting both customer_id and meter_slug to null. ````