> For the complete documentation index, see [llms.txt](https://docs.fastrouter.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fastrouter.ai/explore-features/web-search.md).

# Web Search

## Introduction

FastRouter supports two ways to give a model access to live web results:

1. **Native web search** — for models that ship with built-in search, controlled via the `web_search_options` parameter.
2. **`:online` suffix** — appends Exa-powered web search results to *any* model on FastRouter.

***

### Native Web Search

When using a web-search-enabled model, you can pass the `web_search_options` parameter to control how much search context is retrieved and processed. Models with this capability dynamically integrate search results into their reasoning process.

These models apply a per-request fee, and additionally charge based on search context size, which controls how much data is retrieved and processed per query.

#### Web-Search Enabled Models

These models support built-in web search:

* `openai/gpt-4o-mini-search-preview`
* `openai/gpt-4o-search-preview`
* `perplexity/sonar-pro`
* `perplexity/sonar-reasoning-pro`
* `perplexity/sonar`
* `perplexity/sonar-reasoning`

#### Search Context Size

The `search_context_size` setting controls how much information is pulled from search results. Pricing varies based on the selected level.

| Level    | Description                                        | Use Case                           |
| -------- | -------------------------------------------------- | ---------------------------------- |
| `low`    | Minimal context for basic queries                  | Quick facts, dates, headlines      |
| `medium` | Moderate context with broader information coverage | General knowledge, short summaries |
| `high`   | Extensive search context for deep research         | In-depth topics, analysis, reports |

#### Sample Request

This example uses `openai/gpt-4o-mini-search-preview` with medium search context to get real-time sports event info:

```bash
curl --location 'https://api.fastrouter.ai/api/v1/chat/completions' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer API-KEY' \
--data '{
  "model": "openai/gpt-4o-mini-search-preview",
  "messages": [
    {
      "role": "user",
      "content": "Which teams are playing the UEFA Champions League final?"
    }
  ],
  "stream": false,
  "top_p": 1,
  "temperature": 0,
  "max_completion_tokens": 120,
  "web_search_options": {
    "search_context_size": "medium"
  }
}'
```

***

### Enabling Web Search for Any Model (`:online`)

You can incorporate relevant web search results for *any* model on FastRouter by appending **`:online`** to the model slug. Search is performed by **Exa**, and the retrieved results are injected into the model's context before the completion is generated — so this works with models that have no native search capability of their own.

```json
{
  "model": "openai/gpt-oss-20b:online"
}
```

#### Sample Request

```bash
curl --location 'https://api.fastrouter.ai/api/v1/chat/completions' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer API-KEY' \
--data '{
  "model": "openai/gpt-oss-20b:online",
  "messages": [
    {
      "role": "user",
      "content": "Which teams are playing the UEFA Champions League final?"
    }
  ],
  "stream": false
}'
```

***

### Pricing

Billing depends on which method you use.

| Method            | Search cost                                                 | Model cost                                      |
| ----------------- | ----------------------------------------------------------- | ----------------------------------------------- |
| Native web search | Charged by the provider (per request + search context size) | Standard token pricing for that model           |
| `:online` (Exa)   | **$7 per 1,000 requests**                                   | Standard token pricing for the underlying model |

Both are billed against your FastRouter credits.

With `:online`, the Exa search fee is charged per request that triggers a search, and is separate from the token cost of the model you pair it with. Search results injected into the prompt count toward your input tokens.


---

# Agent Instructions
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## Querying This Documentation
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Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.fastrouter.ai/explore-features/web-search.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.