Steam Library Shortcuts

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January 2024

Source mods under /sourcemods/, when configured correctly, show up on Steam Library after a restart. Source Mods placed in |all_source_engine_paths|, GoldSrc mods or even Source 2 mods don't show up by default.

Steam shortcuts file

Any game/mod could by added to the Steam Library by creating a shortcut. The shortcuts file for a given user are located under the directory steam_install_dir\\userdata\\, and the path ends with config. The shortcuts are stored inside this directory, in a file named shortcuts.vdf.

Shortcut format

This format represents every property used as of 2025.

public class Shortcut
{
    public byte[]? AppId { get; set; }
    public string? AppName { get; set; }
    public string? Exe { get; set; }
    public string? StartDir { get; set; }
    public string? Icon { get; set; }
    public string? ShortcutPath { get; set; }
    public string? LaunchOptions { get; set; }
    public bool IsHidden { get; set; }
    public bool AllowDesktopConfig { get; set; }
    public bool AllowOverlay { get; set; }
    public bool OpenVR { get; set; }
    public bool Devkit { get; set; }
    public string? DevkitGameID { get; set; }
    public byte[]? DevkitOverrideAppID { get; set; }
    public byte[]? LastPlayTime { get; set; }
    public string? FlatpakAppID { get; set; }
    public List<string> Tags { get; set; } = new List<string>();
}

Reading the shortcuts.vdf

For the format structure, see Adding Non-Steam Games.

For how the script is set up, see How to read VDF binary.

public static List<Shortcut> ReadShortcuts(string filepath)
{
    if (!File.Exists(filepath))
	{
	    Console.WriteLine($"The file '{filepath}' does not exist.");
	    return []; 
	}

	if (new FileInfo(filepath).Length == 0)
	{
	    Console.WriteLine($"The file '{filepath}' is empty, use 'BuildShortcuts()' with an empty list");
	    return [];
	}
	
    using var fs = File.OpenRead(filepath);
    using var reader = new BinaryReader(fs, Encoding.UTF8);

    byte rootType = reader.ReadByte();
    string rootKey = ReadNullTerminatedString(reader);

    if (rootType != 0x00 || rootKey != "shortcuts")
        throw new Exception("Unexpected root key or type");

    var shortcuts = new List<Shortcut>();

    while (true)
    {
        byte type = reader.ReadByte();
        if (type == 0x08) break; // end of shortcuts dictionary

        if (type != 0x00)
            throw new Exception($"Expected dictionary key (0x00), got 0x{type:X2}");

        string index = ReadNullTerminatedString(reader);

        Shortcut shortcut = ParseShortcut(reader);
        shortcuts.Add(shortcut);
    }

    return shortcuts;
}

private static Shortcut ParseShortcut(BinaryReader reader)
{
    var sc = new Shortcut();

    while (true)
    {
        byte type = reader.ReadByte();
        if (type == 0x08) break; // end of this shortcut dict

        string key = ReadNullTerminatedString(reader);

        switch (type)
        {
            case 0x00: // nested dict, e.g. tags
                if (key == "tags")
                    sc.Tags = ParseTags(reader);
                else
                    SkipDictionary(reader);
                break;
            case 0x01: // string
                string val = ReadNullTerminatedString(reader);
                AssignString(sc, key, val);
                break;
            case 0x02: // int32
                int intval = reader.ReadInt32();
                AssignInt(sc, key, intval);
                break;
            default:
                throw new Exception($"Unknown type 0x{type:X2} for key '{key}'");
        }
    }

    return sc;
}

private static List<string> ParseTags(BinaryReader reader)
{
    var tags = new List<string>();
    while (true)
    {
        byte type = reader.ReadByte();
        if (type == 0x08) break; // end of tags dict

        string key = ReadNullTerminatedString(reader);

        if (type != 0x01)
            throw new Exception($"Unexpected type in tags dict: 0x{type:X2}");

        string val = ReadNullTerminatedString(reader);
        tags.Add(val);
    }
    return tags;
}

private static void SkipDictionary(BinaryReader reader)
{
    while (true)
    {
        byte type = reader.ReadByte();
        if (type == 0x08) break; // end of dictionary

        string key = ReadNullTerminatedString(reader);

        switch (type)
        {
            case 0x00:
                SkipDictionary(reader);
                break;
            case 0x01:
                ReadNullTerminatedString(reader);
                break;
            case 0x02:
                reader.ReadInt32();
                break;
            default:
                throw new Exception($"Unknown type 0x{type:X2} while skipping dict");
        }
    }
}

private static void AssignString(Shortcut sc, string key, string val)
{
    switch (key)
    {
        case "AppName": sc.AppName = val; break;
        case "Exe": sc.Exe = val; break;
        case "StartDir": sc.StartDir = val; break;
        case "icon": sc.Icon = val; break;
        case "ShortcutPath": sc.ShortcutPath = val; break;
        case "LaunchOptions": sc.LaunchOptions = val; break;
        case "FlatpakAppID": sc.FlatpakAppID = val; break;
        case "DevkitGameID": sc.DevkitGameID = val; break;
        default: break; // unknown string keys ignored
    }
}

private static void AssignInt(Shortcut sc, string key, int val)
{
    switch (key)
    {
        case "appid": sc.AppId = BitConverter.GetBytes(val); break;
        case "IsHidden": sc.IsHidden = val != 0; break;
        case "AllowDesktopConfig": sc.AllowDesktopConfig = val != 0; break;
        case "AllowOverlay": sc.AllowOverlay = val != 0; break;
        case "OpenVR": sc.OpenVR = val != 0; break;
        case "Devkit": sc.Devkit = val != 0; break;
        case "DevkitOverrideAppID": sc.DevkitOverrideAppID = BitConverter.GetBytes(val); break;
        case "LastPlayTime": sc.LastPlayTime = BitConverter.GetBytes(val); break;
        default: break; // unknown int keys ignored
    }
}

private static string ReadNullTerminatedString(BinaryReader reader)
{
    var bytes = new List<byte>();
    while (true)
    {
        byte b = reader.ReadByte();
        if (b == 0) break;
        bytes.Add(b);
    }
    return Encoding.UTF8.GetString(bytes.ToArray());
}

// to read and return data, use this somewhere:
List<Shortcut> shortcuts = (YourClassName.)ReadShortcuts(filePath);

Writing the shortcuts.vdf

This should correctly add images with the id.

It must be added with bytes, or Steam will generate a random id for images.

public static byte[] BuildShortcuts(List<Shortcut> shortcuts)
{
    var seenAppIds = new HashSet<string>();

    for (int i = 0; i < shortcuts.Count; i++)
    {
        if (shortcuts[i].AppId == null)
            continue;

        string appIdString = BitConverter.ToString(shortcuts[i].AppId);
        if (seenAppIds.Contains(appIdString))
        {
            Console.WriteLine($"Warning: Duplicate AppID found: {appIdString}. Aborting shortcut build.");
            return Array.Empty<byte>();
        }
        seenAppIds.Add(appIdString);
    }

    using var ms = new MemoryStream();
    using var writer = new BinaryWriter(ms, Encoding.UTF8);

    writer.Write((byte)0x00); // null terminator
    writer.Write(Encoding.ASCII.GetBytes("shortcuts"));
    writer.Write((byte)0x00);

    if (shortcuts.Count > 0)
    {
        for (int i = 0; i < shortcuts.Count; i++)
        {
            writer.Write((byte)0x00); // null terminator
            writer.Write(Encoding.ASCII.GetBytes(i.ToString()));
            writer.Write((byte)0x00);

            writer.Write(BuildShortcut(shortcuts[i]));

            writer.Write((byte)0x08); // end of shortcut
        }
    }
    else
    {
        Console.WriteLine("Warning: Empty list recived, no shortcuts to write.");
    }

    writer.Write((byte)0x08); // end of shortcuts dict
    writer.Write((byte)0x08); // end of root dict

    return ms.ToArray();
}

 private static byte[] BuildShortcut(Shortcut shortcut)
 {
     using var ms = new MemoryStream();
     using var writer = new BinaryWriter(ms, Encoding.UTF8);

     // Write AppID: type (0x02), key, null terminator, then 4 raw bytes (no terminator)
     writer.Write((byte)0x02); // int32 type
     writer.Write(Encoding.ASCII.GetBytes("appid"));
     writer.Write((byte)0x00);
     if (shortcut.AppId != null && shortcut.AppId.Length == 4)
         writer.Write(shortcut.AppId);
     else
         writer.Write(new byte[4] { 0, 0, 0, 0 });

     // Write string keys: type (0x01), key, null, value, null
     WriteStringField(writer, "AppName", shortcut.AppName);
     WriteStringField(writer, "Exe", shortcut.Exe);
     WriteStringField(writer, "StartDir", shortcut.StartDir ?? "");
     WriteStringField(writer, "icon", shortcut.Icon ?? "");
     WriteStringField(writer, "ShortcutPath", shortcut.ShortcutPath ?? "");
     WriteStringField(writer, "LaunchOptions", shortcut.LaunchOptions ?? "");

     // Write booleans: type (0x02), key, null, 4-byte int (0 or 1)
     WriteBoolField(writer, "IsHidden", shortcut.IsHidden);
     WriteBoolField(writer, "AllowDesktopConfig", shortcut.AllowDesktopConfig);
     WriteBoolField(writer, "AllowOverlay", shortcut.AllowOverlay);
     WriteBoolField(writer, "OpenVR", shortcut.OpenVR);
     WriteBoolField(writer, "Devkit", shortcut.Devkit);

     WriteStringField(writer, "DevkitGameID", shortcut.DevkitGameID ?? "");

     // DevkitOverrideAppID and LastPlayTime are int32 fields, or 0 if null
     WriteIntField(writer, "DevkitOverrideAppID", GetIntFromBytes(shortcut.DevkitOverrideAppID));
     WriteIntField(writer, "LastPlayTime", GetIntFromBytes(shortcut.LastPlayTime));

     WriteStringField(writer, "FlatpakAppID", shortcut.FlatpakAppID ?? "");

     // Write tags as nested key-values
     WriteTags(writer, shortcut.Tags);

     return ms.ToArray();
 }

 // Helper to write string fields
 private static void WriteStringField(BinaryWriter writer, string key, string value)
 {
     writer.Write((byte)0x01); // string type
     writer.Write(Encoding.ASCII.GetBytes(key));
     writer.Write((byte)0x00);
     writer.Write(Encoding.UTF8.GetBytes(value));
     writer.Write((byte)0x00);
 }

 // Helper to write bool fields (int32 with 0 or 1)
 private static void WriteBoolField(BinaryWriter writer, string key, bool value)
 {
     writer.Write((byte)0x02); // int32 type
     writer.Write(Encoding.ASCII.GetBytes(key));
     writer.Write((byte)0x00);
     writer.Write(value ? 1 : 0);
 }

 // Helper to write int32 fields
 private static void WriteIntField(BinaryWriter writer, string key, int value)
 {
     writer.Write((byte)0x02); // int32 type
     writer.Write(Encoding.ASCII.GetBytes(key));
     writer.Write((byte)0x00);
     writer.Write(value);
 }
 private static int GetIntFromBytes(byte[] bytes)
 {
     if (bytes == null || bytes.Length < 4) return 0;
     return BitConverter.ToInt32(bytes, 0);
 }

 // Helper to write tags dictionary
 private static void WriteTags(BinaryWriter writer, List<string> tags)
 {
     writer.Write((byte)0x00); // begin dict
     writer.Write(Encoding.ASCII.GetBytes("tags"));
     writer.Write((byte)0x00);

     for (int i = 0; i < tags.Count; i++)
     {
         writer.Write((byte)0x01); // string type
         writer.Write(Encoding.ASCII.GetBytes(i.ToString()));
         writer.Write((byte)0x00);
         writer.Write(Encoding.UTF8.GetBytes(tags[i]));
         writer.Write((byte)0x00);
     }

     writer.Write((byte)0x08); // end dict
 }
 public static void WriteShortcuts(string filePath, List<Shortcut> shortcuts)
 {
     using var fs = new FileStream(filePath, FileMode.Create, FileAccess.Write);
     using var writer = new BinaryWriter(fs, Encoding.UTF8);

     // Write root dictionary start
     writer.Write((byte)0x00);
     writer.Write(Encoding.UTF8.GetBytes("shortcuts"));
     writer.Write((byte)0x00);

     for (int i = 0; i < shortcuts.Count; i++)
     {
         writer.Write((byte)0x00); // dictionary key type (string)
         writer.Write(Encoding.UTF8.GetBytes(i.ToString()));
         writer.Write((byte)0x00);

         // Write shortcut binary data
         var shortcutBytes = BuildShortcut(shortcuts[i]);
         writer.Write(shortcutBytes);

         writer.Write((byte)0x08); // end of shortcut dictionary
     }

     // Write final end markers for shortcuts dictionary
     writer.Write((byte)0x08);
     writer.Write((byte)0x08);
 }

Get AppId for a shortcut

To display an image in the library, the app id of the shortcut must be known. What has been tested so far is that the app id is given by the following method:

In order to add a steam short cut, Steam must be shut downed or it wont add the shortcut.

private static uint ComputeCRC32(byte[] bytes)
{
    const uint Polynomial = 0xEDB88320;
    uint[] table = new uint[256];
    for (uint i = 0; i < 256; i++)
    {
        uint temp = i;
        for (int j = 0; j < 8; j++)
            temp = (temp & 1) == 1 ? (Polynomial ^ (temp >> 1)) : (temp >> 1);
        table[i] = temp;
    }

    uint crc = 0xFFFFFFFF;
    foreach (byte b in bytes)
    {
        byte index = (byte)((crc & 0xFF) ^ b);
        crc = (crc >> 8) ^ table[index];
    }
    return ~crc;
}

public static uint GenerateAppID(Shortcut shortcut)
{
    string combined = shortcut.AppName + shortcut.Exe + "\0";

    Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
    byte[] data = Encoding.GetEncoding("Windows-1252").GetBytes(combined);

    uint crc = ComputeCRC32(data);
    return crc | 0x80000000;
}

public static string GenerateEncryptedAppID(Shortcut shortcut)
{
    uint appid = GenerateAppID(shortcut);

    byte[] bytes = BitConverter.GetBytes(appid);
    if (!BitConverter.IsLittleEndian)
        Array.Reverse(bytes);

    return Encoding.Latin1.GetString(bytes);
}

Main program for writing shortcuts.vdf

class Program { public static void CreateSteamGrid(uint appid, string sourceFolder, string destinationFolder) { if (appid == 0) { Console.WriteLine("Invalid appid provided. Cannot create Steam grid images."); return; } try { // Ensure the destination directory exists System.IO.Directory.CreateDirectory(destinationFolder); // Define source files and their target names var fileMap = new Dictionary<string, string> { { "ID_hero.png", $"{appid}_hero.png" }, { "ID_600x900.png", $"{appid}.png" }, { "ID_logo.png", $"{appid}_logo.png" }, { "ID.json", $"{appid}.json" } }; foreach (var pair in fileMap) { string sourcePath = System.IO.Path.Combine(sourceFolder, pair.Key); string destPath = System.IO.Path.Combine(destinationFolder, pair.Value); if (System.IO.File.Exists(sourcePath)) { System.IO.File.Copy(sourcePath, destPath, true); } else { Console.WriteLine($"Warning: Source file not found: {sourcePath}"); } } } catch (Exception ex) { Console.WriteLine($"Error creating Steam grid images: {ex.Message}"); } } static void Main() { List<Shortcut> shortcuts = new List<Shortcut> { new Shortcut { AppName = "My Custom Game", Exe = @"""C:\Path\to\the.exe""", StartDir = @"C:\Path\to\StartDir\", Icon = "", ShortcutPath = "", LaunchOptions = "", IsHidden = false, AllowDesktopConfig = true, AllowOverlay = true, OpenVR = false, Devkit = false, DevkitGameID = null, DevkitOverrideAppID = null, FlatpakAppID = null } }; uint appId = (YourClassNane.)GenerateAppID(shortcuts[0]); shortcuts[0].AppId = BitConverter.GetBytes(appId); byte[] shortcutData = (YourClassName.)BuildShortcuts(shortcuts); File.WriteAllBytes(@"C:\Program Files (x86)\Steam\userdata\<user id>\config\shortcuts.vdf", shortcutData); (YourClassName.)CreateSteamGrid(appId, @"C:\Path\to\template images\", @"C:\Program Files (x86)\Steam\userdata\<user id>\config\grid\"); Console.WriteLine("Proccess done, you can safely close the window."); } }

Main program for reading shortcuts.vdf

class Program { static void Main(string[] args) { Console.WriteLine("Enter the path to your shortcuts file:"); string? inputPath = Console.ReadLine(); inputPath = inputPath?.Replace('\\', '/'); // Normalize path separators string filePath = string.IsNullOrWhiteSpace(inputPath) ? "shortcuts.vdf" : (inputPath.EndsWith(".vdf", StringComparison.OrdinalIgnoreCase) ? inputPath : $"{inputPath.TrimEnd('/', '\\')}/shortcuts.vdf"); Console.WriteLine("Reading from: " + filePath); // Read shortcuts from file, returns a list List<Shortcut> shortcuts = (YourClassName.)ReadShortcuts(filePath); // Display the shortcuts if (shortcuts.Count != 0) { Console.WriteLine("Shortcuts found:"); foreach (var shortcut in shortcuts) { Console.WriteLine($"AppId: {BitConverter.ToUInt32(shortcut.AppId, 0)}"); // Decodes the id correctly Console.WriteLine($"AppName: {shortcut.AppName}"); Console.WriteLine($"Exe: {shortcut.Exe}"); Console.WriteLine($"StartDir: {shortcut.StartDir}"); Console.WriteLine($"Icon: {shortcut.Icon}"); Console.WriteLine($"ShortcutPath: {shortcut.ShortcutPath}"); Console.WriteLine($"LaunchOptions: {shortcut.LaunchOptions}"); Console.WriteLine($"IsHidden: {shortcut.IsHidden}"); Console.WriteLine($"AllowDesktopConfig: {shortcut.AllowDesktopConfig}"); Console.WriteLine($"AllowOverlay: {shortcut.AllowOverlay}"); Console.WriteLine($"OpenVR: {shortcut.OpenVR}"); Console.WriteLine($"Devkit: {shortcut.Devkit}"); Console.WriteLine($"DevkitGameID: {shortcut.DevkitGameID}"); Console.WriteLine($"DevkitOverrideAppID: {BitConverter.ToInt32(shortcut.DevkitOverrideAppID, 0)}"); Console.WriteLine($"FlatpakAppID: {shortcut.FlatpakAppID}"); Console.WriteLine($"LastPlayTime: {BitConverter.ToInt32(shortcut.LastPlayTime, 0)}"); Console.WriteLine("Tags: " + string.Join(", ", shortcut.Tags)); Console.WriteLine(new string('-', 40)); } } else { Console.WriteLine("No shortcuts found or file is empty."); return; } } }

See also

• Adding Non-Steam Games
• Binary VDF