# Online & Offline mode¶

## Introduction¶

Qlib supports Online mode and Offline mode. Only the Offline mode is introduced in this document.

The Online mode is designed to solve the following problems:

• Manage the data in a centralized way. Users don’t have to manage data of different versions.
• Reduce the amount of cache to be generated.
• Make the data can be accessed in a remote way.

## Qlib-Server¶

Qlib-Server is the assorted server system for Qlib, which utilizes Qlib for basic calculations and provides extensive server system and cache mechanism. With QLibServer, the data provided for Qlib can be managed in a centralized manner. With Qlib-Server, users can use Qlib in Online mode.

## Reference¶

If users are interested in Qlib-Server and Online mode, please refer to Qlib-Server Project and Qlib-Server Document.