---
title: Functions Overview
description: Learn how to create, test, and apply VRL functions in OpenObserve to transform stream data during ingestion using the UI or API.
---

# Functions Overview

In OpenObserve, functions are VRL (Vector Remap Language) scripts that transform your stream data. You create and manage functions via the OpenObserve UI or API. In the UI, go to **Pipelines > Functions** to open a built-in editor where you can write, test, and save VRL code. Once saved, a function can be associated with a stream so it runs on incoming data at ingest time. 

**Learn more**:

- [Functions in OpenObserve](functions-in-openobserve.md)
- [Create and Manage Functions Using API](../../../reference/api/function/index.md)

**Related link**:

- [SQL References](../../../reference/sql-reference.md)