Left 4 Dead Authoring Tools

The Left 4 Dead Authoring Tools is a set of tools and resources used to create custom content, modifications to Left 4 Dead, or even completely new games using Source engine technology. The package is also sometimes referred to as the SDK, or Software Developer's Kit. Anyone can download and try these tools, but please note that they are designed for advanced users.

Included:
For community support and an online knowledgebase, please visit the Valve Developer Community.

The tools will be updated over time with new resources and examples. As with Steam games, these updates will be delivered by Steam automatically.