What is the VDF file format?
.VDF files use Valve's KeyValues text format - a hierarchical key-value data structure developed for the Steam platform and Source engine games. The format was introduced in 2004 alongside Steam and *Half-Life 2* and is found throughout thousands of configuration, manifest, and game-data files on any Steam installation.
A .vdf file is plain text: quoted keys map to either quoted string values or nested { } blocks, in a structure that mirrors JSON but uses no commas or colons. Common uses include Steam library manifests, game configuration files, server settings, and mod metadata. Being human-readable, .vdf files can be opened and edited in any text editor.
A binary variant of KeyValues also exists, used internally by some engine components, with type tags encoded as raw bytes. The format has evolved through KeyValues 1 (Source engine, 2004), KeyValues 2, and KeyValues3 (KV3, .kv3 / .vdata), introduced with Source 2 and used in Dota 2, CS2, and other titles.
Note: Avira (formerly AntiVir) also uses the .vdf extension for its virus definition database files (vbase000.vdf), which are proprietary binary blobs unrelated to Valve's format.
Security & safety
RISK: LOWText VDF files are harmless plain text and cannot execute code. Be careful editing Steam manifest files - a malformed appmanifest can cause Steam to re-download an entire game. Never edit Avira's binary .vdf definition files; doing so can break antivirus protection. Avoid downloading 'Steam config fix' VDF files from unofficial sources - they could redirect Steam to malicious update servers.
Format details
in a nutshell- Avira AntiVir Virus Definition - Proprietary binary files (vbase000.vdf, vbase001.vdf, …) containing antivirus signatures; downloaded automatically by Avira; no public format spec.
- VariCAD Drawing File - VariCAD 3D/2D CAD software uses .vdf for its drawing format on Linux/Windows.
Programs that open VDF files
Windows3 apps
Notepad
Open-source Open the .vdf file in Notepad++; use View → Language → JSON for approximate syntax highlighting. 
Visual Studio Code
Open-source Open with VS Code; install a KeyValues/VDF syntax extension from the marketplace for highlighting. 
macOS1 app
Visual Studio Code
Open-source Open with VS Code for text editing with optional VDF syntax extension. 
Linux1 app
Visual Studio Code
Open-source Open with VS Code or any text editor (gedit, nano) - VDF is plain text. Technical details
deep spec| File encoding | Plain text (UTF-8 or UTF-16 LE) for standard VDF; binary for the KeyValues binary variant |
| Syntax | Recursive quoted key-value pairs in { } blocks; no commas or colons (unlike JSON) |
| Format versions | KeyValues 1 (Source engine, 2004); KeyValues 2; KeyValues3 / KV3 (Source 2, 2019) |
| Binary variant byte order | Little-endian; type tags encoded as single bytes before each key and value |
| Encryption | None; Steam client verifies manifest integrity externally via checksums |
| Typical file size | 1 KB - 5 MB (most configs are small; large library manifests may reach a few MB) |
| MIME type | text/plain |
| Common use cases | Steam appmanifest_*.acf library manifests, game config files, Workshop metadata, server settings |
| Supported platforms | Windows, Linux, macOS (cross-platform Steam) |
| Successor format | KeyValues3 (.kv3 / .vdata) for Source 2 titles such as Dota 2, CS2, and Half-Life: Alyx |
| Alternative .vdf use | Avira AntiVir virus definition files (vbase000.vdf) - binary blobs unrelated to Valve's format |
| Released | 2004 (with the Source engine and Steam) |
| Latest version | KeyValues3 (KV3, 2019, used in Dota 2 / Source 2) |
| Specification | developer.valvesoftware.com |
VDF conversions
Community Q&A
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