# User Libraries

Previously, library code could only be written by Caplin and had to be placed within the _libs_ directory of the BladeRunner SDK.

From Caplin Trader 3.5.0, BladeRunner has _user library_ support. Using the `create-library` command in BladeRunner, you are now able to create and write your own JavaScript libraries inside an existing app directory.

## What are the benefits?

This newly created user library is recognisable by BladeRunner as a standard library within the _libs_ directory. This enables you to conveniently share your library code across multiple apps and aspects, and with other users of BladeRunner. You can simply share the functions and features of your library between projects by the use of a [symbolic link](https://en.wikipedia.org/wiki/Symbolic_link).

Say, for example you’ve developed a piece of code inside your application, and you wish to export the code into another app. You can now export and share the relevant JS files in your _user library_ so that you can continue to use and develop your code outside of your current application/SDK directory.

_For more on how to create your own libraries, see [here](bladerunner-create-my-own-library-in-bladerunner.md)._