Source SDK Base 2013

SDK Base Info & SDK 2006, 2007 (Legacy)

SDK Base 2013 (About)

Setup - SDK Base 2013 SP

Setup - SDK Base 2013 MP (TF2)

SDK Base Beta

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Source SDK Base 2013 - Singleplayer and Source SDK Base 2013 - Multiplayer are necessary dependencies for mods based on Source 2013. They are responsible for bootstrapping the Source engine when launching a mod and include essential parts of the source code that are not publicly available in the official SDK. Both are available to all Steam users under the 'tools' section on the Library page. As the name implies, Source SDK Base 2013 is locked to the Source 2013 engine branch, to prevent incompatible engine updates from making mods unusable.

Since Source 2013 is split into three sub-branches, there is:

• On Source SDK Base 2013 - Singleplayer:
  • Source 2013 Singleplayer.
• On Source SDK Base 2013 - Multiplayer:
  • Team Fortress 2 branch - current version.
  • Source 2013 Multiplayer - legacy branch (previous2021, see below).

Tip:Despite its name, you can make a singleplayer mod using Source SDK Base 2013 - Multiplayer, but you MUST use the legacy branch ():

• The Multiplayer branch provides additional features (static prop lightmaps, BSP compression, more ambient cubes per visleaf, and slightly newer code).
• This may be desirable over the Singleplayer branch if not using a base mod such as Mapbase and not making a single-player mod with game code untouched (this process requires you to modify the code).

Bug:The Team Fortress 2 branch version of Source SDK Base 2013 - Multiplayer makes some changes which break singleplayer mode:

• save loading does not work correctly[1].
• attempting to load any map with maxplayers and cl_localnetworkbackdoor both set to 1 will crash the game[2] (not affected on "sourcetest" (Source Engine Test)).

SDK Base versions

There are two versions of Source SDK Base 2013:

• Source SDK Base 2013 - Multiplayer (AppID: 243750 - Click to Install)

Note:This branch originally ran on Source 2013 Multiplayer, but it has been upgraded to the Team Fortress 2 branch, which might be incompatible with mods built on the legacy version of Source SDK Base 2013 - Multiplayer (that runs on Source 2013 Multiplayer).
To downgrade to legacy version of Source SDK Base 2013 Multiplayer, follow the instructions:

1. Open Steam, go to Source SDK 2013 Multiplayer, right click Properties
2. A window will open. Go to "Betas", select previous2021 beta branch.
3. Steam will automatically re-download the files. Once it's done, run Source SDK Base 2013 MP as normal, or use its tools.

• Source SDK Base 2013 - Singleplayer (AppID: 243730 - Click to Install)

Note:By default, many sourcemods (including Mapbase), will crash when launched, unless you select the upcoming branch.
To select upcoming branch, follow the instructions:

1. Open Steam, go to Source SDK 2013 Singleplayer, right click Properties
2. A window will open. Go to "Betas", select upcoming beta branch.
3. Steam will automatically re-download the files. Once it's done, try to launch the mod again.

Note:Currently, as of May 30, 2025, this branch has yet to receive updates with new features from Half-Life 2's 20th Anniversary Update (radial fog, classic particles, etc.) or the Team Fortress 2 branch, aswell as bug fixes introduced with later version of Half-Life 2 (and other Source games).
The latest version of Source SDK Base 2013 SP are from June 2014, while upcoming branch are last updated in September 2014. Gamecode for the SP branch are last updated in September 2015.

Setting up & compiling code

To set up Source SDK 2013 and compiling mods, see:

• Setting up Source SDK Base 2013 Multiplayer - for Team Fortress 2 branch (using post-2025 Source SDK Base 2013 - Multiplayer)
• Setting up Source SDK Base 2013 Singleplayer - for Source 2013 Singleplayer (using Source SDK Base 2013 - Singleplayer)
  • Source code for this SDK is not yet updated, unlike the TF2 branch, and will require using an older version of Visual Studio or GCC to compile.
  • Also applies to legacy (pre-2025) version of Source SDK Base 2013 - Multiplayer.

SDK Base Content

Singleplayer branch

• Source Engine Test (sourcetest)
• Half-Life 2: Episode Two shared (ep2)
• Half-Life 2: Episode One shared (episodic)
• Half-Life 2 shared (hl2)
• Source 2013 Singleplayer branch (32-bit binaries only)

Multiplayer branch

• Source Engine Test (sourcetest)
  • Note:Source Engine Test can only be launched with 32-bit binaries.
• Half-Life 2: Deathmatch shared (hl2mp)
• Half-Life 2 Complete (hl2_complete)
• Half-Life 2 shared (hl2)
• Team Fortress 2 branch (32/64-bit binaries)

Known issues

If there are any issues or bugs with Source SDK 2013, including SDK Base, search for existing bugs or report it here on GitHub:

• Source SDK 2013 - GitHub Issues