Answer

`POST https://api.keirolabs.cloud/api/v2/answer`

Cost: 1 credits paid · 2 free · Latency: ~4 s

Provides an authoritative, LLM-synthesized direct answer to your question with cited sources. Powered by a multi-provider reasoning stack with Keiro retrieval and citation synthesis layered on top. Supports both Server-Sent Events (SSE) streaming and standard JSON responses.

**When to use it.** Use Answer when you need a direct, synthesized response to a question — like asking an expert. Returns a text answer with cited sources. Ideal for chatbots, Q&A systems, and grounding LLM outputs.

**When not to.** Don't use Answer if you need raw search results (use Search), page content (use Search+Content), or multi-step autonomous research with charts (use Web Agent).

## Request

**cURL**

```bash
curl -N -X POST https://api.keirolabs.cloud/api/v2/answer \
  -H "Authorization: Bearer $KEIRO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"query": "what is the context window of claude opus?"}'
```

**Python**

```python
import os, requests

res = requests.post(
    "https://api.keirolabs.cloud/api/v2/answer",
    headers={"Authorization": f"Bearer {os.environ['KEIRO_API_KEY']}"},
    json={
        "query": "what is the context window of claude opus?"
    },
    stream=True,
)
for line in res.iter_lines():
    print(line.decode())
```

**Node.js**

```js
const res = await fetch("https://api.keirolabs.cloud/api/v2/answer", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.KEIRO_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "query": "what is the context window of claude opus?"
  }),
});
for await (const chunk of res.body) process.stdout.write(chunk);
```

## Parameters

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| `query` | string | yes | The question to answer. No hard length limit, but keep under 1,000 chars for best synthesis quality. |
| `stream` | boolean | no | Stream the response via Server-Sent Events (SSE). Default: true. When true, the response uses text/event-stream and emits chunk events with the running answer text, followed by a final done event. |
| `noCache` | boolean | no | Bypass the search cache and force a fresh web search. Default: false. |

## Response

```json title="200 OK"
{
  "answer": "The 2024 US Presidential Election was won by Donald Trump (R), defeating incumbent Kamala Harris (D). Trump secured 312 electoral votes to Harris's 226, with a decisive popular-vote margin of ~2.3%.",
  "sources": [
    {
      "title": "2024 United States presidential election - Wikipedia",
      "url": "",
      "domain": "wikipedia",
      "snippet": "..."
    },
    {
      "title": "Federal Election Commission official results",
      "url": "",
      "domain": "fec.gov",
      "snippet": "..."
    }
  ],
  "stats": {
    "sources_count": 2,
    "latency_ms": 3820,
    "credits_used": 5,
    "attempt": "ai-search"
  },
  "creditsRemaining": 1095
}
```

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| `answer` | string | no | LLM-synthesized answer text with inline citations. |
| `sources` | array | no | List of sources cited in the answer. |
| `sources[].title` | string | no | Title of the source page. |
| `sources[].url` | string | no | URL of the source. |
| `sources[].domain` | string | no | Domain name of the source. |
| `sources[].snippet` | string | no | Relevant excerpt from the source. |
| `stats.sources_count` | integer | no | Number of sources used. |
| `stats.latency_ms` | integer | no | Total processing time. |
| `stats.credits_used` | number | no | Credits charged (2 on Free, 1 on paid plans). |
| `creditsRemaining` | number | no | Your remaining credit balance. |

## Errors

| Status | Code | Cause | Fix |
| --- | --- | --- | --- |
| `400` | `VALIDATION_ERROR` | Missing query | Provide a non-empty query string. |
| `401` | `UNAUTHORIZED` | Missing or invalid API key | Check your Authorization: Bearer header. |
| `402` | `INSUFFICIENT_CREDITS` | Not enough credits (need 2, or 1 on paid plans) | Top up or upgrade at /dashboard/billing. |
| `429` | `RATE_LIMIT_EXCEEDED` | Too many requests | Answer is rate-limited at 10/min (free) to 200/min (enterprise). |
| `502` | `SEARCH_UNAVAILABLE` | LLM provider failure | Credits auto-refunded. Retry with backoff. |

## Rate limits

| Tier | Limit |
| --- | --- |
| Free | 10/min |
| Starter | 30/min |
| Pro | 60/min |
| Startup | 120/min |
| Enterprise | 200/min |

Over the limit you get a `429`. See [Rate limits](/rate-limits) for headers and backoff.