--- description: Search and chat with AI Search instances from a Cloudflare Worker using the Workers binding. title: Workers binding image: https://developers.cloudflare.com/og-docs.png --- [Skip to content](#main-content) > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/ai-search/llms.txt > Use this file to discover all available pages before exploring further. # Workers binding Last updated Aug 24, 2026|Copy as Markdown|[View as Markdown](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/ai-search/api/search/workers-binding/index.md)|[Agent setup](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/agent-setup/) [Workers](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/workers/) provides a serverless execution environment that allows you to create new applications or augment existing ones. Use a [Workers binding](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/workers/runtime-apis/bindings/) to search and chat with your AI Search instances from a Cloudflare Worker. Note The previous `env.AI.autorag()` binding is no longer recommended for use. Refer to [Workers binding migration](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/ai-search/api/migration/workers-binding/) for details. ## Configure the binding To use AI Search with Workers, you must create an AI Search binding. You create bindings by updating your [Wrangler configuration](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/workers/wrangler/configuration/). AI Search provides two types of bindings: * Namespace binding: `ai_search_namespaces` * Instance binding: `ai_search` ### Namespace binding Access all instances within a [namespace](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/ai-search/concepts/namespaces/). You can get, create, list, and delete instances at runtime. ```jsonc { "$schema": "./node_modules/wrangler/config-schema.json", "compatibility_date": "2026-03-27", "ai_search_namespaces": [ { "binding": "AI_SEARCH", "namespace": "my-namespace" } ] } ``` ```toml compatibility_date = "2026-03-27" [[ai_search_namespaces]] binding = "AI_SEARCH" namespace = "my-namespace" ``` | Field | Type | Required | Description | | --------- | ------- | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | binding | string | Yes | The variable name available on env. For example, "AI\_SEARCH" makes it accessible as env.AI\_SEARCH. | | namespace | string | Yes | The [namespace](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/ai-search/concepts/namespaces/) to bind to. A default namespace is created automatically for every account. If the namespace does not exist, Wrangler creates it on deploy. | | remote | boolean | No | Set to true for local development with wrangler dev. | ### Instance binding Bind directly to a single instance in the `default` namespace. Use this when you know which instance you need at deploy time. ```jsonc { "$schema": "./node_modules/wrangler/config-schema.json", "compatibility_date": "2026-03-27", "ai_search": [ { "binding": "MY_SEARCH", "instance_name": "my-instance" } ] } ``` ```toml compatibility_date = "2026-03-27" [[ai_search]] binding = "MY_SEARCH" instance_name = "my-instance" ``` | Field | Type | Required | Description | | -------------- | ------- | -------- | ---------------------------------------------------------------------------------------------------- | | binding | string | Yes | The variable name available on env. For example, "MY\_SEARCH" makes it accessible as env.MY\_SEARCH. | | instance\_name | string | Yes | The name of the AI Search instance. Must exist in the default namespace at deploy time. | | remote | boolean | No | Set to true for local development with wrangler dev. | ## Instance methods 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()` Search for relevant content chunks from your indexed data source. Returns scored chunks with source references. ```ts const instance = env.AI_SEARCH.get("my-instance"); const results = await instance.search({ messages: [{ role: "user", content: "What is Cloudflare?" }], }); ``` #### Parameters `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](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/ai-search/configuration/retrieval/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`. #### Response The response contains the following fields: | Field | Type | Description | | -------------------------------------------- | ------ | ------------------------------------------------------------------------------------ | | search\_query | string | The query used for the search, which may be rewritten if query rewriting is enabled. | | chunks | array | An array of matching content chunks. | | chunks\[\].id | string | The unique identifier for the chunk. | | chunks\[\].type | string | The type of content, typically text. | | chunks\[\].score | number | The overall match score between 0 and 1. | | chunks\[\].text | string | The text content of the chunk. | | chunks\[\].item | object | Information about the source item. | | chunks\[\].item.key | string | The file path or URL of the source document. | | chunks\[\].item.timestamp | number | Unix timestamp of when the item was last modified. | | chunks\[\].item.metadata | object | Custom metadata associated with the source item. | | chunks\[\].scoring\_details | object | Breakdown of how the chunk was scored. | | chunks\[\].scoring\_details.vector\_score | number | The semantic similarity score (0 to 1). | | chunks\[\].scoring\_details.keyword\_score | number | The keyword (BM25) match score. Present when using hybrid or keyword retrieval. | | chunks\[\].scoring\_details.keyword\_rank | number | The keyword rank position. | | chunks\[\].scoring\_details.vector\_rank | number | The vector rank position. | | chunks\[\].scoring\_details.reranking\_score | number | The reranking score (0 to 1). Present when reranking is enabled. | | chunks\[\].scoring\_details.fusion\_method | string | The fusion method used (rrf or max). Present when using hybrid retrieval. | ### `chatCompletions()` Generate chat completions using your AI Search instance as context. This method retrieves relevant content and uses it to generate a response. ```ts 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, }, }, }); ``` #### Stream responses Set `stream: true` to receive responses as Server-Sent Events (SSE) as they are generated: ```ts 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. #### Parameters `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](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/ai-search/configuration/models/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](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/ai-search/configuration/retrieval/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`. #### Response (non-streaming) | Field | Type | Description | | --------------------------- | ------ | ----------------------------------------------------------------------------------- | | id | string | Unique identifier for the completion. | | object | string | Always chat.completion. | | created | number | Unix timestamp of when the completion was created. | | model | string | The model used to generate the response. | | choices | array | Array of completion choices. | | choices\[\].message.role | string | Always assistant. | | choices\[\].message.content | string | The generated response text. | | choices\[\].finish\_reason | string | Why the model stopped generating. Typically stop. | | usage.prompt\_tokens | number | Number of tokens in the prompt. | | usage.completion\_tokens | number | Number of tokens in the generated response. | | usage.total\_tokens | number | Total tokens used. | | chunks | array | The source chunks used as context. Same format as the [search response](#response). | #### Response (streaming) 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. ```txt 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] ``` ## Namespace methods 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`). ### `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. ```ts const results = await env.AI_SEARCH.search({ messages: [{ role: "user", content: "What is Cloudflare?" }], ai_search_options: { instance_ids: ["product-docs", "customer-abc123"], }, }); ``` #### Parameters Same as [instance-level search](#parameters), with one additional required field: | Parameter | Type | Required | Description | | --------------------------------- | ------ | -------- | ----------------------------------------------------- | | ai\_search\_options | object | Yes | Required for namespace-level search. | | ai\_search\_options.instance\_ids | array | Yes | Instance IDs to search across. Minimum 1, maximum 10. | #### Response Same as [instance-level search](#response), with additional fields: | Field | Type | Description | | ----------------------- | ------ | -------------------------------------------------------------------------------------- | | chunks\[\].instance\_id | string | The instance this chunk came from. | | errors | array | Per-instance errors if any instances failed. Each object has instance\_id and message. | ### `chatCompletions()` Generate chat completions using context retrieved from multiple instances. ```ts 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`. #### Parameters Same as [instance-level chat completions](#parameters-1), with one additional required field: | Parameter | Type | Required | Description | | --------------------------------- | ------ | -------- | ----------------------------------------------------- | | ai\_search\_options | object | Yes | Required for namespace-level chat completions. | | ai\_search\_options.instance\_ids | array | Yes | Instance IDs to search across. Minimum 1, maximum 10. | #### Response Same as [instance-level chat completions](#response-non-streaming), with additional fields on each chunk: | Field | Type | Description | | ----------------------- | ------ | -------------------------------------------------------------------------------------- | | chunks\[\].instance\_id | string | The instance this chunk came from. | | errors | array | Per-instance errors if any instances failed. Each object has instance\_id and message. | ## Local development 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`. ```jsonc // wrangler.jsonc { "ai_search": [ { "binding": "MY_SEARCH", "instance_name": "my-instance", "remote": true, }, ], } ``` Was this helpful? 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Build, secure, and scale without managing infrastructure","url":"https://www.cloudflare.com/","sameAs":["https://github.com/cloudflare","https://www.linkedin.com/company/cloudflare","https://x.com/cloudflare"],"logo":{"@type":"ImageObject","url":"https://developers.cloudflare.com/logo.svg"},"address":{"@type":"PostalAddress","streetAddress":"101 Townsend St","addressLocality":"San Francisco","addressRegion":"CA","postalCode":"94107","addressCountry":"US"},"contactPoint":[{"@type":"ContactPoint","contactType":"Customer Support","url":"https://support.cloudflare.com/","availableLanguage":["English"]},{"@type":"ContactPoint","contactType":"Sales","url":"https://www.cloudflare.com/contact/","availableLanguage":["English"]}]},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"}} ```