[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Type](https://evolu.dev/docs/api-reference/common/Type) › lowercased

```ts
function lowercased<ParentType>(
  parent: ValidateBrandParent<"Lowercased", ParentType>,
): Type<"Lowercased">;
```

Defined in: [packages/common/src/Type.ts:6442](https://github.com/evoluhq/evolu/blob/dd96d79f1dbe9a49fa12ce8e0aa7d3d0177795ca/packages/common/src/Type.ts#L6442)

Adds lowercased text validation to an existing string Type.

Narrows the output to TypeScript's `Lowercase<string>` while preserving the
parent Type's constraints. Validation leaves the text unchanged. Use
[lowercase](https://evolu.dev/docs/api-reference/common/Type/functions/lowercase) to change its casing.

### Example

```ts
import {
  assertErr,
  assertOk,
  lowercased,
  maxLength,
  String,
} from "@evolu/common";

const Label = lowercased(maxLength(50)(String));
assertOk(Label.fromUnknown("hello world"), "hello world");
assertErr(Label.fromUnknown("Hello WORLD"));
```