Answer API - LLMLAYER API Documentation

Overview

The Answer API combines live web search with LLM generation in one request. Use it when you need:

Current information from the web
Source-backed responses
Structured output (JSON) for downstream processing
Streaming UX for chat and copilots

Endpoints

Endpoint	Method	Best for	Supports JSON output
`/api/v2/answer`	`POST`	Standard request/response flows	Yes
`/api/v2/answer_stream`	`POST` (SSE)	Real-time streaming UX	No

provider_key is deprecated and currently ignored by both endpoints. It is still accepted for backward compatibility.

Authentication

All requests require:

Authorization: Bearer YOUR_LLMLAYER_API_KEY

Keep API keys server-side. Do not expose them in browser code.

Model Selection

Model	Pricing model	Best for
`llmlayer-web`	Flat `$0.007 × max_queries`	Default recommendation
`llmlayer-fast`	Flat `$0.009 × max_queries`	Faster responses
`openai/gpt-4o-mini`	Token pricing + LLMLayer fee	Budget + quality
`openai/gpt-5.1`	Token pricing + LLMLayer fee	Highest reasoning quality

If unsure, start with llmlayer-web and max_queries=1.

Quickstart

Non-streaming (`/answer`)

import { LLMLayerClient } from 'llmlayer';

const client = new LLMLayerClient({
  apiKey: process.env.LLMLAYER_API_KEY,
});

const response = await client.answer({
  query: 'What are the latest developments in quantum computing?',
  model: 'llmlayer-web',
  returnSources: true,
});

console.log(response.answer);
console.log('Sources:', response.sources?.length || 0);
console.log('LLMLayer cost:', response.llmlayer_cost);

Example response (simplified):

{
  "answer": "...",
  "sources": [
    {
      "title": "...",
      "link": "https://...",
      "snippet": "..."
    }
  ],
  "response_time": "2.14",
  "input_tokens": 1432,
  "output_tokens": 288,
  "model_cost": null,
  "llmlayer_cost": 0.007
}

Streaming (`/answer_stream`)

import { LLMLayerClient } from 'llmlayer';

const client = new LLMLayerClient({
  apiKey: process.env.LLMLAYER_API_KEY,
});

const stream = client.streamAnswer({
  query: 'Explain retrieval-augmented generation in simple terms',
  model: 'openai/gpt-4o-mini',
  returnSources: true,
});

for await (const event of stream) {
  if (event.type === 'answer') {
    process.stdout.write(event.content || '');
  } else if (event.type === 'sources') {
    console.log('\n\nSources:', event.data?.length || 0);
  } else if (event.type === 'usage') {
    console.log('\nCost:', (event.model_cost || 0) + (event.llmlayer_cost || 0));
  } else if (event.type === 'done') {
    console.log('\nDone in', event.response_time, 'seconds');
  }
}

Request Parameters

This is the canonical request-body table for both endpoints.

Parameter	Type	Required	Default	Applies to	Cost impact	Details
`query`	`string`	Yes	-	Both	-	User question/instruction
`model`	`string`	Yes	-	Both	Depends on model	Example: `llmlayer-web`, `openai/gpt-4o-mini`
`search_type`	`string`	No	`general`	Both	-	`general` or `news`
`date_filter`	`string`	No	`anytime`	Both	-	`anytime`, `hour`, `day`, `week`, `month`, `year`
`location`	`string`	No	`us`	Both	-	Country code for localized search
`domain_filter`	`string[]`	No	`null`	Both	-	Include domains, or exclude with `-` prefix
`search_context_size`	`string`	No	`medium`	Both	Indirect	`low`, `medium`, `high`
`max_queries`	`integer`	No	`1`	Both	Increases LLMLayer fee	Range `1-4`
`max_tokens`	`integer`	No	`1500`	Both	Increases model usage	Response length cap
`temperature`	`number`	No	`0.7`	Both	-	Range `0.0-2.0`
`response_language`	`string`	No	`auto`	Both	-	Example: `en`, `fr`, `es`
`citations`	`boolean`	No	`false`	Both	Indirect	Adds inline citation markers
`return_sources`	`boolean`	No	`false`	Both	-	Includes `sources` array
`return_images`	`boolean`	No	`false`	Both	`+ $0.001`	Includes `images` array
`answer_type`	`string`	No	`markdown`	`/answer`	-	`markdown`, `html`, `json`
`json_schema`	`object` or `string`	Conditional	`null`	`/answer`	-	Required when `answer_type="json"`
`system_prompt`	`string`	No	`null`	Both	-	Custom behavior instructions
`provider_key`	`string`	No	`null`	Both	-	Deprecated, accepted, ignored

HTTP requests use snake_case field names. JavaScript SDK examples use camelCase.

Parameter Rules

max_queries must be between 1 and 4.
answer_type="json" requires json_schema.
/api/v2/answer_stream does not support structured JSON output.
provider_key does not change routing or billing.
Use -domain.com in domain_filter to exclude domains.

Non-streaming Response Contract (`/answer`)

Field	Type	When present	Description
`answer`	`string \| object`	Always	Generated answer (`object` when JSON mode)
`sources`	`array`	If `return_sources=true`	Source documents used
`images`	`array`	If `return_images=true`	Image search results
`response_time`	`string`	Always	Total processing time in seconds
`input_tokens`	`integer`	Always	Input token usage
`output_tokens`	`integer`	Always	Output token usage
`model_cost`	`number \| null`	Usually	Model usage cost
`llmlayer_cost`	`number`	Always	LLMLayer infrastructure cost

Source objects typically include title, link, snippet (plus provider-specific extras). Image objects typically include title, imageUrl, thumbnailUrl, source, link.

Streaming Event Contract (`/answer_stream`)

The stream is Server-Sent Events (text/event-stream). Each frame contains JSON under data:.

Event type	Payload	Notes
`sources`	`{ "type": "sources", "data": Source[] }`	Emitted when `return_sources=true`
`images`	`{ "type": "images", "data": Image[] }`	Emitted when `return_images=true`
`answer`	`{ "type": "answer", "content": "..." }`	Main text chunks
`usage`	`{ "type": "usage", "input_tokens": ..., "output_tokens": ..., "model_cost": ..., "llmlayer_cost": ... }`	Billing and token usage
`done`	`{ "type": "done", "response_time": "..." }`	Final event
`error`	`{ "type": "error", "error": "..." }`	Runtime stream error

Example stream sequence:

{"type":"sources","data":[...]}
{"type":"answer","content":"The "}
{"type":"answer","content":"main idea ..."}
{"type":"usage","input_tokens":1234,"output_tokens":210,"model_cost":0.0002,"llmlayer_cost":0.004}
{"type":"done","response_time":"2.41"}

On early setup failures, some clients may receive an immediate frame like { "error": "missing_query" }.

Practical Examples

1) News summary with citations

{
  "query": "Latest developments in renewable energy",
  "model": "openai/gpt-5.1",
  "search_type": "news",
  "date_filter": "week",
  "citations": true,
  "return_sources": true,
  "max_queries": 2
}

2) Structured JSON extraction (`/answer` only)

{
  "query": "Summarize top AI model launches this month",
  "model": "openai/gpt-5.1",
  "answer_type": "json",
  "json_schema": {
    "type": "object",
    "properties": {
      "summary": { "type": "string" },
      "items": {
        "type": "array",
        "items": { "type": "string" }
      }
    },
    "required": ["summary", "items"]
  }
}

3) Domain-constrained answer

{
  "query": "What are current type 2 diabetes treatment guidelines?",
  "model": "openai/gpt-5.1",
  "domain_filter": ["pubmed.gov", "nih.gov", "-reddit.com"],
  "search_context_size": "high",
  "temperature": 0.3,
  "return_sources": true
}

Error Handling

`/answer` error format

{
  "detail": {
    "error_type": "validation_error",
    "error_code": "missing_query",
    "message": "Query parameter cannot be empty",
    "details": null
  }
}

Common status codes

Status	Category	Typical reason
`400`	Validation	Missing/invalid request parameters
`401`	Authentication	Missing or invalid LLMLayer API key
`429`	Rate limit/provider	Provider or account rate limiting
`500`	Internal/provider	Unexpected backend/provider failure
`502`	Provider	Upstream provider-specific failure

`/answer_stream` errors

Runtime failures are emitted as stream events (type: error).
Early validation failures can appear as an immediate single error frame.

Pricing

Standard token-priced models

Total = (0.004 × max_queries)
      + model_input_cost
      + model_output_cost
      + (0.001 if return_images=true)

LLMLayer fixed-price models

llmlayer-web  = 0.007 × max_queries
llmlayer-fast = 0.009 × max_queries

Use llmlayer_cost and model_cost from responses as the billing source of truth.

Implementation Checklist

Start with /answer unless you need progressive rendering.
Set max_queries=1 first; increase only for research-style queries.
Enable return_sources=true for trust-sensitive use cases.
Use answer_type="json" + json_schema for structured pipelines.
Add retry/backoff logic for transient 429/500/502 paths.
Keep keys server-side and log llmlayer_cost + token usage.

FAQ

When should I use /answer_stream instead of /answer?

Use /answer_stream for chat UIs and live typing effects. Use /answer for batch jobs, strict request/response flows, and JSON structured output.

Can I stream JSON structured output?

No. Streaming returns incremental text chunks and does not support JSON schema-constrained output.

How do I control source quality?

Use domain_filter, search_type, date_filter, and search_context_size together. For factual tasks, use lower temperature.

Is provider_key still supported?

It is accepted to avoid breaking older clients, but currently ignored.

How do I minimize cost?

Start with llmlayer-web, keep max_queries=1, only request images/sources when needed, and tune max_tokens to expected output length.

Next Steps

Web Search API

Raw search results without LLM generation

Scraper API

Extract full page content from URLs

Answer Stream Endpoint

OpenAPI reference for SSE endpoint

Python SDK

Python package and usage examples

TypeScript SDK

JS/TS package and usage examples

Need Help?

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Ask implementation questions

Email Support

support@llmlayer.ai

Get Started

​Overview

​Endpoints

​Authentication

​Model Selection

​Quickstart

​Non-streaming (/answer)

​Streaming (/answer_stream)

​Request Parameters

​Parameter Rules

​Non-streaming Response Contract (/answer)

​Streaming Event Contract (/answer_stream)

​Practical Examples

​1) News summary with citations

​2) Structured JSON extraction (/answer only)

​3) Domain-constrained answer

​Error Handling

​/answer error format

​Common status codes

​/answer_stream errors

​Pricing

​Standard token-priced models

​LLMLayer fixed-price models

​Implementation Checklist

​FAQ

​Next Steps

Web Search API

Scraper API

Answer Stream Endpoint

Python SDK

TypeScript SDK

​Need Help?

Discord Community

Email Support

Overview

Endpoints

Authentication

Model Selection

Quickstart

Non-streaming (`/answer`)

Streaming (`/answer_stream`)

Request Parameters

Parameter Rules

Non-streaming Response Contract (`/answer`)

Streaming Event Contract (`/answer_stream`)

Practical Examples

1) News summary with citations

2) Structured JSON extraction (`/answer` only)

3) Domain-constrained answer

Error Handling

`/answer` error format

Common status codes

`/answer_stream` errors

Pricing

Standard token-priced models

LLMLayer fixed-price models

Implementation Checklist

FAQ

Next Steps

Need Help?