RepSeedResolver

UE5 Blueprint replication handle & net field resolver, built on CUE4Parse.

Scans .pak files to discover Blueprint classes and resolves their replication layout handles and ClassNetCache indices using C++ seed data from RepSeedDumper.

Download

Pre-built binaries are available on the Releases page.

Requires .NET 8.0 Runtime (win-x64).

Output

Produces two JSON files:

• rep_layout.json — Per-class replication property handles with 1-based indices, inheriting from the C++ seed and appending BP-defined replicated properties
• class_net_cache.json — Per-class net field export indices, combining seed net fields with BP properties and RPCs

Build

git clone --recurse-submodules https://github.com/Mokocoder/RepSeedResolver.git
dotnet publish -c Release

Usage

1. Set Paks Dir to the game's pak folder
2. Load Seed JSON (replication_seed.json from RepSeedDumper)
3. Select Game version
4. (Optional) Load .usmap mappings
5. Click Run

How it works

1. CUE4Parse mounts the game's pak files and loads mappings
2. Scans all packages for UBlueprintGeneratedClass exports using the global script object index for fast filtering
3. For each BP class, collects replicated properties (EPropertyFlags::Net) and net RPCs (FUNC_Net)
4. Walks the BP inheritance chain to find the C++ ancestor in the seed data
5. Appends BP handles after the C++ seed handles, preserving UE's FRepLayout wire ordering
6. Accumulates net field counts up the chain to produce correct ClassNetCache max indices