Options

Option	Type	Default	Description
validate	boolean	true	Validate the spec before parsing
contentType	'application/json' | string	—	Preferred media type for request and response schemas
server	{ index?: number, variables?: Record<string, string> }	—	Which server URL plugins use as the base URL
discriminator	'preserve' | 'propagate'	'preserve'	How discriminator fields are interpreted
enums	'inline' | 'root'	'inline'	Where inline enums live
dateType	false | 'string' | 'stringOffset' | 'stringLocal' | 'date'	'string'	How format: date-time schemas are represented
integerType	'number' | 'bigint'	'bigint'	How integers map to TypeScript
unknownType	'any' | 'unknown' | 'void'	'any'	Type for schemas Kubb cannot infer
emptySchemaType	'any' | 'unknown' | 'void'	unknownType | 'any'	Type for empty schemas
enumSuffix	string	'enum'	Suffix for derived enum names

validate

Validates the OpenAPI spec with @readme/openapi-parser before parsing. Set it to false only when you have a known-invalid spec that you still want to generate from.

Type:	boolean
Default:	true

contentType

Preferred media type when an operation defines several. Operations with multiple media types use this one.

Without a value, it falls back to the first JSON-compatible media type found in the spec (application/json, application/vnd.api+json, or any *+json).

Type:	'application/json' | string

server

Selects which entry in the spec's servers array becomes the base URL, and supplies values for its {variable} placeholders. Plugins that need a base URL read it from here (@kubb/plugin-axios, @kubb/plugin-fetch, @kubb/plugin-msw).

server.index points at one of the spec's servers. Most projects pick 0 for the primary server and use higher indices for staging or localhost. server.variables fills in any {variable} placeholders in the selected URL, falling back to each variable's default from the spec. Omit server to leave baseURL undefined.

Type:	{ index?: number, variables?: Record<string, string> }

TIP

Plugins read baseURL from this server unless they override it explicitly.

Server variables substitute into the {variable} placeholders in the selected URL. With a spec server of https://api.{env}.example.com, setting server: { index: 0, variables: { env: 'prod' } } resolves baseURL to https://api.prod.example.com.

discriminator

How discriminator fields on oneOf/anyOf schemas are interpreted.

• 'preserve' (default) keeps child schemas exactly as written. The discriminator narrows types at the call site, but child shapes stay the same.
• 'propagate' pushes the discriminator property with its literal value into each child schema, so each branch's type field is precisely typed.

Type:	'preserve' | 'propagate'
Default:	'preserve'

OpenAPI spec

openapi: 3.0.3
components:
  schemas:
    Animal:
      required: [type]
      type: object
      oneOf:
        - $ref: '#/components/schemas/Cat'
        - $ref: '#/components/schemas/Dog'
      discriminator:
        propertyName: type
        mapping:
          cat: '#/components/schemas/Cat'
          dog: '#/components/schemas/Dog'
    Cat:
      type: object
      properties:
        type:
          type: string
        indoor:
          type: boolean
    Dog:
      type: object
      properties:
        type:
          type: string
        name:
          type: string

'preserve' (default)

export type Cat = {
  type: string
  indoor?: boolean
}

export type Dog = {
  type: string
  name?: string
}

export type Animal = Cat | Dog

'propagate'

export type Cat = {
  type: 'cat'
  indoor?: boolean
}

export type Dog = {
  type: 'dog'
  name?: string
}

export type Animal = Cat | Dog

enums

Where inline enums live.

• 'inline' (default) keeps each enum on the property that declares it.
• 'root' lifts every inline enum to a reusable top-level schema named after its context (for example PetStatusEnum) and references it wherever it appears.

Type:	'inline' | 'root'
Default:	'inline'

OpenAPI spec

openapi: 3.0.3
components:
  schemas:
    Pet:
      type: object
      properties:
        status:
          type: string
          enum: [active, inactive]

'inline' (default)

export type Pet = {
  status?: 'active' | 'inactive'
}

'root'

export type PetStatusEnum = 'active' | 'inactive'

export type Pet = {
  status?: PetStatusEnum
}

dateType

How format: date-time schemas are represented downstream.

• false falls through to a plain string with no validation.
• 'string' (default) emits an ISO 8601 datetime string.
• 'stringOffset' emits a datetime string with a timezone offset.
• 'stringLocal' emits a local datetime string with no timezone.
• 'date' emits a JavaScript Date. Best for client code, though JSON needs parsing to revive it.

Type:	false | 'string' | 'stringOffset' | 'stringLocal' | 'date'
Default:	'string'

The string variants all emit string at the TypeScript type level. The offset and local distinction surfaces in schema output such as Zod.

string variants

// false, 'string', 'stringOffset', 'stringLocal' → string
type CreatedAt = string

'date'

// format: date-time → JavaScript Date
type CreatedAt = Date

integerType

How type: integer (and format: int64) maps to TypeScript.

• 'bigint' (default) is exact for 64-bit IDs, but JSON.stringify and JSON.parse cannot round-trip it. Use it only when you handle bigint serialization yourself.
• 'number' fits most JSON APIs. It loses precision above Number.MAX_SAFE_INTEGER.

Type:	'number' | 'bigint'
Default:	'bigint'

'bigint' (default)

type Pet = {
  id: bigint
}

'number'

type Pet = {
  id: number
}

unknownType

AST type used when a schema's type cannot be inferred from the spec (additionalProperties: true, a missing type, and similar).

Pick 'unknown' to force callers to narrow before using the value. 'any' is the loosest. 'void' matches some legacy APIs.

Type:	'any' | 'unknown' | 'void'
Default:	'any'

'any' (default)

type Pet = {
  extra: any
}

'unknown'

type Pet = {
  extra: unknown
}

'void'

type Pet = {
  extra: void
}

emptySchemaType

AST type used for fully empty schemas ({}). It follows unknownType unless you set it. Override it only when empty schemas should be treated differently from unresolvable ones.

Type:	'any' | 'unknown' | 'void'
Default:	unknownType | 'any'

TIP

A common pairing sets unknownType: 'unknown' for safety and emptySchemaType: 'any' so empty 204 response bodies stay easy to use.

'any' (default)

// empty schema {} → any
type EmptyModel = any

'unknown'

// empty schema {} → unknown
type EmptyModel = unknown

enumSuffix

Suffix appended to derived enum names when Kubb has to invent one, typically for inline enums on object properties.

An inline enum on a status property becomes statusEnum with the default. Change it to align with your project's naming convention.

Type:	string
Default:	'enum'

'enum' (default)

// Property `status` with inline enum values
const statusEnum = { available: 'available', pending: 'pending' } as const
type StatusEnum = (typeof statusEnum)[keyof typeof statusEnum]

'type'

const statusType = { available: 'available', pending: 'pending' } as const
type StatusType = (typeof statusType)[keyof typeof statusType]