# `createIdGenerator()`

Creates a customizable ID generator function. You can configure the alphabet, prefix, separator, and default size of the generated IDs.

```ts
import { createIdGenerator } from 'ai';

const generateCustomId = createIdGenerator({
  prefix: 'user',
  separator: '_',
});

const id = generateCustomId(); // Example: "user_1a2b3c4d5e6f7g8h"
```

## Import

<Snippet text={`import { createIdGenerator } from "ai"`} prompt={false} />

## API Signature

### Parameters

<PropertiesTable
  content={[
    {
      name: 'options',
      type: 'object',
      description:
        'Optional configuration object with the following properties:',
    },
    {
      name: 'options.alphabet',
      type: 'string',
      description:
        'The characters to use for generating the random part of the ID. Defaults to alphanumeric characters (0-9, A-Z, a-z).',
    },
    {
      name: 'options.prefix',
      type: 'string',
      description:
        'A string to prepend to all generated IDs. Defaults to none.',
    },
    {
      name: 'options.separator',
      type: 'string',
      description:
        'The character(s) to use between the prefix and the random part. Defaults to "-".',
    },
    {
      name: 'options.size',
      type: 'number',
      description:
        'The default length of the random part of the ID. Defaults to 16.',
    },
  ]}
/>

### Returns

Returns a function that generates IDs based on the configured options.

### Notes

- The generator uses non-secure random generation and should not be used for security-critical purposes.
- The separator character must not be part of the alphabet to ensure reliable prefix checking.

## Example

```ts
// Create a custom ID generator for user IDs
const generateUserId = createIdGenerator({
  prefix: 'user',
  separator: '_',
  size: 8,
});

// Generate IDs
const id1 = generateUserId(); // e.g., "user_1a2b3c4d"
```

## See also

- [`generateId()`](/docs/reference/ai-sdk-core/generate-id)


## Navigation

- [generateText](/v4/docs/reference/ai-sdk-core/generate-text)
- [streamText](/v4/docs/reference/ai-sdk-core/stream-text)
- [generateObject](/v4/docs/reference/ai-sdk-core/generate-object)
- [streamObject](/v4/docs/reference/ai-sdk-core/stream-object)
- [embed](/v4/docs/reference/ai-sdk-core/embed)
- [embedMany](/v4/docs/reference/ai-sdk-core/embed-many)
- [generateImage](/v4/docs/reference/ai-sdk-core/generate-image)
- [transcribe](/v4/docs/reference/ai-sdk-core/transcribe)
- [generateSpeech](/v4/docs/reference/ai-sdk-core/generate-speech)
- [tool](/v4/docs/reference/ai-sdk-core/tool)
- [experimental_createMCPClient](/v4/docs/reference/ai-sdk-core/create-mcp-client)
- [Experimental_StdioMCPTransport](/v4/docs/reference/ai-sdk-core/mcp-stdio-transport)
- [jsonSchema](/v4/docs/reference/ai-sdk-core/json-schema)
- [zodSchema](/v4/docs/reference/ai-sdk-core/zod-schema)
- [valibotSchema](/v4/docs/reference/ai-sdk-core/valibot-schema)
- [CoreMessage](/v4/docs/reference/ai-sdk-core/core-message)
- [createProviderRegistry](/v4/docs/reference/ai-sdk-core/provider-registry)
- [customProvider](/v4/docs/reference/ai-sdk-core/custom-provider)
- [cosineSimilarity](/v4/docs/reference/ai-sdk-core/cosine-similarity)
- [wrapLanguageModel](/v4/docs/reference/ai-sdk-core/wrap-language-model)
- [LanguageModelV1Middleware](/v4/docs/reference/ai-sdk-core/language-model-v1-middleware)
- [extractReasoningMiddleware](/v4/docs/reference/ai-sdk-core/extract-reasoning-middleware)
- [simulateStreamingMiddleware](/v4/docs/reference/ai-sdk-core/simulate-streaming-middleware)
- [defaultSettingsMiddleware](/v4/docs/reference/ai-sdk-core/default-settings-middleware)
- [simulateReadableStream](/v4/docs/reference/ai-sdk-core/simulate-readable-stream)
- [smoothStream](/v4/docs/reference/ai-sdk-core/smooth-stream)
- [generateId](/v4/docs/reference/ai-sdk-core/generate-id)
- [createIdGenerator](/v4/docs/reference/ai-sdk-core/create-id-generator)


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