[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) › UrlSafeString

```ts
const UrlSafeString: regex(
  "UrlSafeString",
  /^[A-Za-z0-9_-]+$/u,
)(String);
```

Defined in: [packages/common/src/Type.ts:5685](https://github.com/evoluhq/evolu/blob/037c390af081e9944d616ff298a729515c5c5ab7/packages/common/src/Type.ts#L5685)

Non-empty URL-safe [String](https://evolu.dev/docs/api-reference/common/Type/variables/String).

Accepts ASCII letters, digits, `-`, and `_`. This is the same alphabet used
by [Base64Url](https://evolu.dev/docs/api-reference/common/Type/variables/Base64Url), but a UrlSafeString is not proof that the text contains
valid Base64Url-encoded bytes.