Unreal Engine Save Files: Why Binary Serialization Beats Text (Proven Tactics for Smaller Saves & Safer Games)

Discover why top studios use binary serialization for Unreal Engine saves. Cut file sizes by 70%, prevent cheating, and ensure cross-platform compatibility with step-by-step code examples. Optimize your UE5 projects today

Table of Contents

• 1. Why Binary Beats Text for Saves
• 2. Security & Anti-Tampering
• 3. Step-by-Step Code Example
• 4. Cross-Platform Byte Handling
• 5. When to Avoid Binary

1. Why Binary Beats Text for Saves

When you save, Unreal serializes your USaveGame object to bytes.
When you load, it unserializes those bytes back into the object.
You don’t write the unserialize logic manually—Unreal handles it internally if you use USaveGame and FArchive correctly.

Why it matters: Binary serialization reduces file size by 60-80% vs JSON/XML. Smaller saves = faster loading and happier players.

// Text (JSON): 2.1KB
{"Health":100, "Inventory":["Sword","Potion"]}

// Binary: 0.7KB (compressed)

2. Security & Anti-Tampering

Key advantages:

• Obfuscation: Binary is harder to edit than plaintext
• Checksums: Add CRC32 to detect tampering
• Encryption: XOR/AES encode byte streams

// Simple XOR encryption
void EncryptSave(TArray& Data) {
for (auto& Byte : Data) Byte ^= 0x5A;
}

3. Step-by-Step Code Example

// 1. Create USaveGame subclass
UCLASS()
class UMySaveData : public USaveGame {
GENERATED_BODY()
public:
UPROPERTY()
int32 Health;

// Serialize to binary
virtual void Serialize(FArchive& Ar) override {
Super::Serialize(Ar);
Ar << Health;
}
};

// 2. Save binary data
UGameplayStatics::SaveGameToSlot(SaveObject, "Slot1", 0);

4. Cross-Platform Byte Handling

Unreal automatically handles:

• Endianness (little/big-endian conversion)
• Platform-specific pathing (Windows/Mac/Consoles)
• Cloud saves via OnlineSubsystem

// Manual endian swap (rarely needed!)
if (Ar.IsLoading() && !Ar.ForceUnicode())
Bytes = ByteSwap(Bytes);

Key Points

• Unreal Automatically Calls Serialize: When loading, Unreal uses your overridden Serialize method to unserialize bytes back into variables.

5. When to Avoid Binary

Use text formats like JSON when:

• Debugging saves (human-readable)
• Allowing player mods/configs
• Storing small non-critical data

// Debug: Export binary to text
FString JsonStr;
FJsonObjectConverter::UStructToJsonObject(SaveData, JsonStr);

Best Practice Summary

Use binary for production saves, text for debugging. Always validate loaded data!

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