Workers binding

Workers provides a serverless execution environment that allows you to create new applications or augment existing ones. Use a Workers binding to search and chat with your AI Search instances from a Cloudflare Worker.

To use AI Search with Workers, you must create an AI Search binding. You create bindings by updating your Wrangler configuration. AI Search provides two types of bindings:

• Namespace binding: ai_search_namespaces
• Instance binding: ai_search

Access all instances within a namespace. You can get, create, list, and delete instances at runtime.

{
  "$schema": "./node_modules/wrangler/config-schema.json",
  "compatibility_date": "2026-03-27",
  "ai_search_namespaces": [
    {
      "binding": "AI_SEARCH",
      "namespace": "my-namespace"
    }
  ]
}

compatibility_date = "2026-03-27"

[[ai_search_namespaces]]
binding = "AI_SEARCH"
namespace = "my-namespace"

Bind directly to a single instance in the default namespace. Use this when you know which instance you need at deploy time.

{
  "$schema": "./node_modules/wrangler/config-schema.json",
  "compatibility_date": "2026-03-27",
  "ai_search": [
    {
      "binding": "MY_SEARCH",
      "instance_name": "my-instance"
    }
  ]
}

compatibility_date = "2026-03-27"

[[ai_search]]
binding = "MY_SEARCH"
instance_name = "my-instance"

The following methods are available on both the ai_search_namespaces and ai_search bindings. With the namespace binding, call methods on the handle returned by get(). With the instance binding, call methods directly on the binding (for example, env.MY_SEARCH.search()).

The examples below use the namespace binding.

Search for relevant content chunks from your indexed data source. Returns scored chunks with source references.

const instance = env.AI_SEARCH.get("my-instance");

const results = await instance.search({
	messages: [{ role: "user", content: "What is Cloudflare?" }],
});

messages array required

An array of message objects representing the conversation. Each message has a role and content field.

• role string required

  • The role of the message sender. Valid values: system, developer, user, assistant, tool.

• content string required

  • The content of the message.

query string optional

A simple text query string. Alternative to messages. Provide either query or messages, not both.

ai_search_options object optional

Configuration options for the search operation.

• retrieval object optional

  • retrieval_type string optional

    • The type of retrieval to perform. Valid values: vector, keyword, hybrid. Defaults to hybrid.

  • match_threshold number optional

    • The minimum match score required for a result to be considered a match. Must be between 0 and 1. Defaults to 0.4.

  • max_num_results integer optional

    • The maximum number of results to return. Must be between 1 and 50. Defaults to 10.

  • filters object optional

    • Filter search results based on metadata. Supports comparison filters (eq, ne, gt, gte, lt, lte) and compound filters (and, or). For more details, refer to Metadata filtering.

  • context_expansion integer optional

    • The number of surrounding chunks to include for additional context. Must be between 0 and 3. Defaults to 0.

  • fusion_method string optional

    • Controls how vector and keyword scores are combined when using hybrid retrieval. Valid values: rrf (Reciprocal Rank Fusion), max (takes the maximum score). Defaults to the instance-level setting.

  • keyword_match_mode string optional

    • Controls how keyword (BM25) matching selects candidate documents. and requires all terms to match. or requires any term to match. Defaults to and.

  • boost_by array optional

    • Boost results by metadata fields. Maximum 3 items. Each item has:
      • field string required - The metadata field name to boost by (for example, timestamp). Maximum 64 characters.
      • direction string optional - The boost direction. Valid values: asc, desc, exists, not_exists. Defaults to asc for numeric fields and exists for text fields.

  • metadata_only boolean optional

    • Return only metadata for each chunk without the text content.

  • return_on_failure boolean optional

    • Whether to return partial results if some processing steps fail. Defaults to true.

• query_rewrite object optional

  • enabled boolean optional

    • Rewrites the query to improve retrieval accuracy. Defaults to false.

  • model string optional

    • The model to use for query rewriting.

  • rewrite_prompt string optional

    • A custom prompt to guide query rewriting.

• reranking object optional

  • enabled boolean optional

    • Reorders retrieved results based on semantic relevance using a reranking model. Defaults to false.

  • model string optional

    • The reranking model to use. Valid value: @cf/baai/bge-reranker-base.

  • match_threshold number optional

    • The minimum score for reranked results. Must be between 0 and 1. Defaults to 0.4.

• cache object optional

  • enabled boolean optional

    • Override the instance-level cache setting for this request.

  • cache_threshold string optional

    • The similarity threshold for cache hits. Valid values: super_strict_match, close_enough, flexible_friend, anything_goes.

The response contains the following fields:

Generate chat completions using your AI Search instance as context. This method retrieves relevant content and uses it to generate a response.

const instance = env.AI_SEARCH.get("my-instance");

const response = await instance.chatCompletions({
	messages: [
		{ role: "system", content: "You are a helpful documentation assistant." },
		{ role: "user", content: "What is Cloudflare?" },
	],
	model: "@cf/meta/llama-3.3-70b-instruct-fp8-fast",
	ai_search_options: {
		retrieval: {
			max_num_results: 5,
		},
		query_rewrite: {
			enabled: true,
		},
	},
});

Set stream: true to receive responses as Server-Sent Events (SSE) as they are generated:

const instance = env.AI_SEARCH.get("my-instance");

const stream = await instance.chatCompletions({
	messages: [{ role: "user", content: "What is Cloudflare?" }],
	stream: true,
});

return new Response(stream, {
	headers: {
		"content-type": "text/event-stream",
		"cache-control": "no-cache",
	},
});

When stream is enabled, the method returns a ReadableStream of SSE events. Each event contains a JSON object with choices[0].delta.content for incremental text. The stream ends with a data: [DONE] event.

messages array required

An array of message objects representing the conversation. Each message has a role and content field.

• role string required

  • The role of the message sender. Valid values: system, developer, user, assistant, tool.

• content string required

  • The content of the message.

model string optional

The text-generation model used to generate responses. Defaults to the generation model configured in the AI Search instance settings. For a list of supported models, refer to Supported models.

stream boolean optional

Returns a stream of results as they are generated. When enabled, returns a Response object with a readable stream. Defaults to false.

ai_search_options object optional

Configuration options for the search and generation operation.

• retrieval object optional

  • retrieval_type string optional

    • The type of retrieval to perform. Valid values: vector, keyword, hybrid. Defaults to hybrid.

  • match_threshold number optional

    • The minimum match score required for a result to be considered a match. Must be between 0 and 1. Defaults to 0.4.

  • max_num_results integer optional

    • The maximum number of results to return. Must be between 1 and 50. Defaults to 10.

  • filters object optional

    • Filter search results based on metadata. Supports comparison filters (eq, ne, gt, gte, lt, lte) and compound filters (and, or). For more details, refer to Metadata filtering.

  • context_expansion integer optional

    • The number of surrounding chunks to include for additional context. Must be between 0 and 3. Defaults to 0.

  • fusion_method string optional

    • Controls how vector and keyword scores are combined when using hybrid retrieval. Valid values: rrf (Reciprocal Rank Fusion), max (takes the maximum score). Defaults to the instance-level setting.

  • keyword_match_mode string optional

    • Controls how keyword (BM25) matching selects candidate documents. and requires all terms to match. or requires any term to match. Defaults to and.

  • boost_by array optional

    • Boost results by metadata fields. Maximum 3 items. Each item has:
      • field string required - The metadata field name to boost by (for example, timestamp). Maximum 64 characters.
      • direction string optional - The boost direction. Valid values: asc, desc, exists, not_exists. Defaults to asc for numeric fields and exists for text fields.

  • metadata_only boolean optional

    • Return only metadata for each chunk without the text content.

  • return_on_failure boolean optional

    • Whether to return partial results if some processing steps fail. Defaults to true.

• query_rewrite object optional

  • enabled boolean optional

    • Rewrites the query to improve retrieval accuracy. Defaults to false.

  • model string optional

    • The model to use for query rewriting.

  • rewrite_prompt string optional

    • A custom prompt to guide query rewriting.

• reranking object optional

  • enabled boolean optional

    • Reorders retrieved results based on semantic relevance using a reranking model. Defaults to false.

  • model string optional

    • The reranking model to use. Valid value: @cf/baai/bge-reranker-base.

  • match_threshold number optional

    • The minimum score for reranked results. Must be between 0 and 1. Defaults to 0.4.

• cache object optional

  • enabled boolean optional

    • Override the instance-level cache setting for this request.

  • cache_threshold string optional

    • The similarity threshold for cache hits. Valid values: super_strict_match, close_enough, flexible_friend, anything_goes.

When stream: true, the method returns a ReadableStream of Server-Sent Events. The retrieved chunks are sent first as a chunks event, followed by the streamed response.

event: chunks
data: [{"id":"chunk-001","type":"text","score":0.85,"text":"...","item":{"key":"about-cloudflare.md","timestamp":1775925540000},"scoring_details":{"vector_score":0.85}}]

data: {"id":"id-1776072781845","created":1776072781,"model":"@cf/meta/llama-3.3-70b-instruct-fp8-fast","object":"chat.completion.chunk","choices":[{"index":0,"delta":{"content":" document"}}]}

data: {"id":"id-1776072781845","created":1776072781,"model":"@cf/meta/llama-3.3-70b-instruct-fp8-fast","object":"chat.completion.chunk","choices":[{"index":0,"delta":{"content":" you provided doesn"}}]}

data: {"id":"id-1776072781845","created":1776072781,"model":"@cf/meta/llama-3.3-70b-instruct-fp8-fast","object":"chat.completion.chunk","choices":[{"index":0,"delta":{"content":"'t contain"}}]}

data: {"id":"id-1776072781845","created":1776072781,"model":"@cf/meta/llama-3.3-70b-instruct-fp8-fast","object":"chat.completion.chunk","choices":[{"index":0,"delta":{"content":" information"}}]}

data: [DONE]

The following methods are only available when using the ai_search_namespaces binding. Search and chat across multiple instances in a single call using the namespace handle directly (env.AI_SEARCH).

Pass instance_ids in ai_search_options to specify which instances to query. Results are merged and ranked, and each chunk includes an instance_id field identifying which instance it came from.

const results = await env.AI_SEARCH.search({
	messages: [{ role: "user", content: "What is Cloudflare?" }],
	ai_search_options: {
		instance_ids: ["product-docs", "customer-abc123"],
	},
});

Same as instance-level search, with one additional required field:

Same as instance-level search, with additional fields:

Generate chat completions using context retrieved from multiple instances.

const response = await env.AI_SEARCH.chatCompletions({
	messages: [{ role: "user", content: "What is Cloudflare?" }],
	ai_search_options: {
		instance_ids: ["product-docs", "customer-abc123"],
	},
});

Streaming is supported with stream: true.

Same as instance-level chat completions, with one additional required field:

Same as instance-level chat completions, with additional fields on each chunk:

Local development is supported by proxying requests to your deployed AI Search instance. Add remote: true to your binding configuration to enable local development with wrangler dev.

// wrangler.jsonc
{
	"ai_search": [
		{
			"binding": "MY_SEARCH",
			"instance_name": "my-instance",
			"remote": true,
		},
	],
}