---
url: /reference/OutputOptions.hashCharacters.md
---
# hashCharacters

* **Type**: `"base64"` | `"base36"` | `"hex"`
* **Optional**

Specify the character set that Rolldown is allowed to use in file hashes.

* `'base64'`: Uses url-safe base64 characters (0-9, a-z, A-Z, -, \_). This will produce the shortest hashes.
* `'base36'`: Uses alphanumeric characters (0-9, a-z)
* `'hex'`: Uses hexadecimal characters (0-9, a-f)

## Default

```ts
'base64'
```