[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) › Base64Url

```ts
const Base64Url:  brand(
  "Base64Url",
  String,
  (value) => {
    const decoded = trySync(() => base64UrlStringToUint8Array(value));

    return decoded.ok && uint8ArrayToBase64UrlString(decoded.value) === value
      ? ok()
      : err<Base64UrlError>({ type: "Base64Url", value });
  },
  (error) =>
    The value ${safelyStringifyUnknownValue(error.value)} is not a valid Base64Url string.,
) ;
```

Defined in: [packages/common/src/Type.ts:5737](https://github.com/evoluhq/evolu/blob/b6ade4b22d4be1758761a2712668e870d3e602c7/packages/common/src/Type.ts#L5737)

Base64Url text without padding.

Convert bytes to Base64Url with [uint8ArrayToBase64Url](https://evolu.dev/docs/api-reference/common/Type/functions/uint8ArrayToBase64Url) and convert
Base64Url to bytes with [base64UrlToUint8Array](https://evolu.dev/docs/api-reference/common/Type/functions/base64UrlToUint8Array).