> ## Documentation Index > Fetch the complete documentation index at: https://docs.leokit.dev/llms.txt > Use this file to discover all available pages before exploring further. # Streaming Quotes > Stream quote results in real-time as each protocol responds via Server-Sent Events ## Overview The streaming-quotes endpoint emits Server-Sent Events as each protocol returns a quote, instead of waiting for all protocols to complete. Use this for snappy UI — display the first quote in \~200ms instead of waiting 5+ seconds for the slowest aggregator. For a hands-on walkthrough see the [Streaming Quotes guide](/guides/streaming-quotes). ## Endpoint ``` GET /leokit/streaming-quotes ``` ## Request ### Authentication EventSource cannot set custom headers reliably, so authentication accepts both styles: | Method | Example | | ------------------------- | ------------------------------------------------- | | `Api-Key` header | `Api-Key: YOUR_API_KEY` (preferred when possible) | | `api_key` query parameter | `?api_key=YOUR_API_KEY` | ### Query Parameters | Parameter | Type | Required | Description | | -------------------- | ------ | -------- | ---------------------------------------------------- | | `from_asset` | string | Yes | Source asset in `CHAIN.SYMBOL-ADDRESS` format | | `to_asset` | string | Yes | Destination asset in `CHAIN.SYMBOL-ADDRESS` format | | `amount` | string | Yes | Amount in source-asset base units (wei, sats, etc.) | | `origin` | string | No | Source wallet address (improves quote accuracy) | | `destination` | string | No | Destination wallet address | | `streaming_interval` | number | No | THORChain/MAYAChain streaming interval (default `1`) | | `streaming_quantity` | number | No | THORChain/MAYAChain streaming sub-swap count | | `api_key` | string | No | Alternative to `Api-Key` header (see above) | ## Response ### Headers ``` Content-Type: text/event-stream Cache-Control: no-cache Connection: keep-alive ``` ### Event Sequence Events are sent as `data: \n\n` chunks (legacy SSE format — no named `event:` fields). | Order | Event payload `type` | Description | | ----- | -------------------- | -------------------------------------------------------------------- | | 1 | `init` | Stream opened, includes `quote_id` and total protocols being queried | | 2..N | `quote` | One per protocol that returns a valid quote | | N+1 | `final` | Aggregated, sorted, deduplicated payload (after all settle) | | N+2 | `finished` | Stream closing | If no protocols return a usable quote, an `error` event is sent in place of `final`. ### Event Payloads ```json theme={null} { "type": "init", "quote_id": "01953c9a-...", "timestamp": "2026-04-28T12:00:00.000Z", "total": 7 } ``` ```json theme={null} { "type": "quote", "protocol": "chainflip", "data": { "expected_amount_out": "0.0498", "fees": [...], "out_asset_decimal": 18, "in_asset_decimal": 8 } } ``` ```json theme={null} { "type": "final", "quote_id": "01953c9a-...", "timestamp": "2026-04-28T12:00:00.000Z", "quotes": [ { "protocol": "chainflip", "data": { "...": "..." }, "expectedAmountOutNum": 0.0498, "totalFeesUsd": 1.23, "totalSwapSeconds": 120, "flags": ["FASTEST"] } ] } ``` ```json theme={null} { "type": "error", "code": "UNABLE_TO_RETRIEVE_QUOTES", "message": "...", "details": [ { "protocol": "thorchain", "message": "Pool unavailable" } ] } ``` ```json theme={null} { "type": "finished" } ``` ### Quote Object Fields (in `final` event) | Field | Description | | ---------------------- | ---------------------------------------------- | | `expectedAmountOutNum` | Numeric expected output (for sorting) | | `totalFeesUsd` | Total combined fees in USD | | `totalSwapSeconds` | Estimated time-to-settle | | `flags` | Tags like `FASTEST`, `CHEAPEST`, `BEST_OUTPUT` | ## Timeouts * **Total budget:** 8 seconds. Protocols that haven't responded by then are dropped. * **Per-protocol circuit breaker:** 5 seconds. Protocols that fail repeatedly are skipped. ## Examples ### Browser (EventSource) ```javascript theme={null} const url = new URL("https://api.leokit.dev/leokit/streaming-quotes"); url.searchParams.set("from_asset", "ETH.ETH"); url.searchParams.set("to_asset", "BTC.BTC"); url.searchParams.set("amount", "1000000000000000000"); url.searchParams.set("api_key", "YOUR_API_KEY"); const es = new EventSource(url.toString()); es.onmessage = (e) => { const event = JSON.parse(e.data); switch (event.type) { case "init": console.log("started", event.quote_id); break; case "quote": console.log("got", event.protocol); break; case "final": console.log("done", event.quotes.length); break; case "finished": es.close(); break; case "error": console.error(event); es.close(); break; } }; ``` ### Server (fetch) ```javascript theme={null} const res = await fetch( "https://api.leokit.dev/leokit/streaming-quotes?from_asset=ETH.ETH&to_asset=BTC.BTC&amount=1000000000000000000", { headers: { "Api-Key": "YOUR_API_KEY" } } ); const reader = res.body.getReader(); const decoder = new TextDecoder(); while (true) { const { value, done } = await reader.read(); if (done) break; const chunk = decoder.decode(value); for (const line of chunk.split("\n\n")) { if (!line.startsWith("data: ")) continue; const event = JSON.parse(line.slice(6)); // handle event } } ``` ## Errors | Status | Code | Description | | ------ | ---------------------- | ---------------------------------------------------------- | | `400` | `BAD_REQUEST` | Missing or malformed `from_asset`, `to_asset`, or `amount` | | `400` | `INVALID_ASSET_FORMAT` | Asset string not in `CHAIN.SYMBOL-ADDRESS` format | | `401` | `INVALID_API_KEY` | Missing or invalid API key | The `UNABLE_TO_RETRIEVE_QUOTES` error is delivered inside the SSE stream as a `type: "error"` event, not as an HTTP error. See the [error codes catalog](/reference/error-codes) for the full list. ## OpenAPI ````yaml /api-reference/openapi.json GET /streaming-quotes openapi: 3.0.3 info: title: Leokit API version: 1.0.0 description: API reference for Leokit servers: - url: https://api.leokit.dev description: Production security: - ApiKeyAuth: [] paths: /streaming-quotes: get: summary: Stream quotes (SSE) description: >- Stream swap quotes as Server-Sent Events (SSE). Quotes are sent individually as they resolve from each protocol, followed by a final sorted result. parameters: - name: from_asset in: query required: true description: Input asset identifier. schema: type: string example: ETH.ETH - name: to_asset in: query required: true description: Output asset identifier. schema: type: string example: BTC.BTC - name: origin in: query required: true description: From wallet address. schema: type: string example: '0xacd9a974065de9c7a19873f95af7595e1d632167' - name: destination in: query required: true description: To wallet address. schema: type: string example: bc1q2hk2q3zy7pdh0tp4awzn4k5lyetedaue5zt88r - name: amount in: query required: true description: Amount to swap. schema: type: string example: '1' - name: api_key in: query required: false description: >- Alternative to Api-Key header (useful for EventSource which cannot set headers). schema: type: string responses: '200': description: >- Server-Sent Events stream. Events are sent as `data: {json}\n\n` format. content: text/event-stream: schema: type: string description: >- SSE stream with events: init, quote (per protocol), final (sorted), finished. example: >+ data: {"type":"init","quote_id":"019b4c6e-d6c2-7000-b851-48a863f2f4b7","timestamp":"2025-12-23T18:18:14.213Z","total":5} data: {"type":"quote","protocol":"thorchain","data":{...}} data: {"type":"final","quotes":[...],"timestamp":"...","quote_id":"..."} data: {"type":"finished"} default: $ref: '#/components/responses/ErrorResponse' components: responses: ErrorResponse: description: Error response content: application/json: schema: $ref: '#/components/schemas/Error' schemas: Error: type: object description: Generic error payload. properties: message: type: string code: type: string securitySchemes: ApiKeyAuth: type: apiKey in: header name: Api-Key description: 'Demo API-Key (Sandbox): 7037d2b3-9c76-4f62-b730-c544f7570fa4' ````