---
page_title: uuidv4 function reference
description: The `uuidv4` function generates a unique string ID according to RFC 4122 version 4.
---

# `uuidv4` Function

`uuidv4` generates a unique identifier string.

The ID is a generated and formatted as required by [RFC 4122 section
4.4](https://tools.ietf.org/html/rfc4122#section-4.4), producing a Version 4
UUID. The result is a UUID generated only from pseudo-random numbers.

This function produces a new value each time it is called, and so using it
directly in resource arguments will result in spurious diffs. We do not
recommend using the `uuidv4` function in resource configurations.

## Examples

```shell-session
> uuidv4()
9fc99a70-7cd5-482d-bb2b-03af016e4e94
```

## Related Functions

- [`uuidv5`](/packer/docs/templates/hcl_templates/functions/uuid/uuidv5), which generates name-based UUIDs.
