@loopback/docs/site/LoopBack-3.x.md

Documentation for LoopBack 4

---
lang: en
title: 'For current LoopBack users'
keywords: LoopBack 4.0, LoopBack 4
sidebar: lb4_sidebar
permalink: /doc/en/lb4/LoopBack-3.x.html
---

LoopBack 4 is the next generation of the LoopBack framework, with a completely
rewritten core foundation and significantly improved programming model. If
you're an existing LoopBack user, read
[Crafting LoopBack 4](Crafting-LoopBack-4.html) to understand the motivations,
strategy, and innovations behind this exciting new version.

For more information on the difference between LoopBack 3 and LoopBack 4, see
[Understanding the differences between LoopBack 3 and LoopBack 4](Understanding-the-differences.md).

To facilitate migration between LoopBack 3 and LoopBack 4, you can mount your
LoopBack 3 application on top of a LoopBack 4 project. See
[Migrating from LoopBack 3](Migrating-from-LoopBack-3.md) for details.