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.

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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:

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.

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

Sample Request

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.