TypeScript configuration | Fern Documentation

Configure the TypeScript SDK in the generation block of its target in sdk-config.yml:

sdk-config.yml

targets:
  - language: typescript
    generation:
      naming:
        clientName: YourClientName
      namespaceExportName: AcmePayments
      packageManager: pnpm
      testFramework: jest

The target’s generation block also accepts the shared generation options, such as naming, wireTests, and customCode. Shared options set in the top-level generation block apply to every target, and a target’s generation block overrides them. For generators.yml options, see the Legacy TypeScript configuration.

TypeScript options

typescriptVersion

string

The TypeScript version used by the generated project.

zodVersion

string

The Zod version used by generated runtime schemas.

compilerOptions

object

TypeScript compiler options for the generated project.

compilerOptions.target

string

The JavaScript language target passed to TypeScript.

compilerOptions.module

string

The module format passed to TypeScript.

compilerOptions.lib

list of string

The runtime library definitions passed to TypeScript.

httpClient

object

The HTTP client used by generated TypeScript code.

<ParamField path=“httpClient.name” type=""axios” | “fetch"" required= toc=> The HTTP client used by generated TypeScript code. </ParamField>

<ParamField path=“packageManager” type=""pnpm” | “yarn"" required= toc=> The package manager used by the generated project. </ParamField>

packageManagerVersion

string

The package manager version used by the generated project.

<ParamField path=“testFramework” type=""jest” | “vitest"" required= toc=> The test framework used by generated tests. </ParamField>

<ParamField path=“namingStrategy” type=""base” | “originalPropertyNames"" required= toc=> How schema property names are converted into TypeScript identifiers. </ParamField>

bundle

boolean

Whether the generated package includes bundled output.

exportClassDefault

boolean

Whether the client class is also exported as the default export.

namespaceExportName

string

The top-level namespace export name.

consolidateTypeFiles

boolean

Whether generated types are consolidated into fewer source files.

allowCustomFetcher

boolean

Whether callers can supply a custom fetch implementation.

useBrandedStringAliases

boolean

Whether string aliases are emitted as distinct branded types.

useLegacyExports

boolean

Whether the package emits the legacy export layout.

useBigInt

boolean

Whether 64-bit integer values are represented with bigint.

serdeLayer

boolean

Whether generated models use Fern serialization and deserialization helpers.

esmOnly

boolean

Whether the package emits only ECMAScript modules.

scripts

list of object

Additional scripts added to the generated package manifest.