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Fatpack

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What Fatpack is

Fatpack is a free Windows tool for packing native x64 Windows PE executables. It compresses targets with LZMA and supports TLS callbacks and TLS data, including for Rust and Delphi programs. It supports native console and Windows executables, but not .NET executables. Resource packing is the default; section packing is experimental and may cause issues with some targets, though the README says it uses less memory at runtime.

Other listed capabilities include relocations, imports and delay imports, exception handlers, memory section protection, manifest extraction, and icon extraction. Fatpack and its loader stubs use WinAPI without the C runtime, so C/C++ redistributables are not required. The documented workflow packages a target executable through the Fatpack.exe command-line tool. The software is available under the MIT License. Its 1.5.2 release notes describe packing failures caused by Windows Defender real-time protection interference, and the releases page lists three assets for that version.

Who it suits

Fatpack is for Windows users packaging native 64-bit console or Windows executables with its command-line tool. Its supported targets exclude .NET programs.

What it does well

  • LZMA compression for native x64 executables
  • Supports TLS callbacks and TLS data
  • Does not require C/C++ redistributables
  • Available under the MIT License

What to know first

  • .NET executables are unsupported
  • Section packing is experimental
  • Windows Defender interference may cause packing failures

Limits

Fatpack supports native x64 console and Windows executables but not .NET executables. Section packing is experimental and may cause issues with some targets; the 1.5.2 release notes also describe possible failure from Windows Defender real-time protection interference.

Getting started

  1. Visit the Fatpack GitHub repository.
  2. Use the release assets listed for version 1.5.2.
  3. Run Fatpack.exe to package a target executable.
  4. Use resource packing by default, or try experimental section packing if its tradeoffs suit the target.

Verdict

Fatpack covers a defined set of Windows PE targets, with TLS support and several executable-processing capabilities. Note the .NET exclusion, the experimental status of section packing, and the reported Defender interference issue.

Questions

What does Fatpack cost?

Fatpack is free and has a perpetual license model.

Which executables does it support?

It supports native x64 console and Windows PE executables. .NET executables are not supported.

What license does Fatpack use?

The repository provides Fatpack under the MIT License.

What platform is it for?

Fatpack is for Windows.

How do I use Fatpack?

The documented workflow uses Fatpack.exe from the command line to package a target executable.

Facts from Fatpack's own pages

Additional features
It supports icon extraction, relocations, imports, delay imports, exception handlers, memory section protection, and manifest extraction. · github.com, 7 Oct 2026
Compression
Fatpack compresses target executables with LZMA. · github.com, 7 Oct 2026
Executable support
It supports native console and Windows executables, but not .NET. · github.com, 7 Oct 2026
Intended users
The documented workflow is for users packaging a target executable with the Fatpack.exe command-line tool. · github.com, 7 Oct 2026
Known issue
The 1.5.2 release notes say packing may fail due to Windows Defender real-time protection interference. · github.com, 7 Oct 2026
License
The repository provides the software under the MIT License. · github.com, 7 Oct 2026
Maker
The GitHub repository identifies its owner as Fatmike-GH. · github.com, 7 Oct 2026
Memory use
The README says section packing is preferred because it requires less memory at runtime. · github.com, 7 Oct 2026
Other capabilities
Listed technical features include relocations, imports, delay imports, exception handlers, memory section protection, and manifest extraction. · github.com, 7 Oct 2026
Packing modes
Resource packing is the default, while section packing is experimental and may cause issues with some targets. · github.com, 7 Oct 2026
Purpose
Fatpack is a Windows PE packer for x64 executables. · github.com, 7 Oct 2026
Release assets
The releases page lists three assets for version 1.5.2. · github.com, 7 Oct 2026
Runtime requirements
Fatpack and its loader stubs use WinAPI without the CRT, so C/C++ redistributables are not required. · github.com, 7 Oct 2026
Section mode limitation
The README says section packing uses less memory at runtime but may cause issues with certain targets. · github.com, 7 Oct 2026
Supported targets
It supports native x64 console and Windows executables; .NET executables are not supported. · github.com, 7 Oct 2026
TLS
It supports TLS callbacks and TLS data, including executables such as Rust and Delphi programs. · github.com, 7 Oct 2026
TLS support
It supports Thread Local Storage, including TLS callbacks and TLS data. · github.com, 7 Oct 2026
What it does
Fatpack is a Windows PE packer for x64 executables using LZMA compression and full TLS support. · github.com, 7 Oct 2026

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