Obfuscar

Obfuscar is a free tool for obfuscating .NET assemblies by renaming their metadata, making decompiled code harder to follow. It suits developers who want a command-line step in a .NET build and can work with XML configuration. Its compact names can also reduce output size, but obfuscation is a deterrent, not a barrier to determined reverse engineering.

Overview

Obfuscar targets .NET assemblies and changes names across methods, properties, events, fields, types and namespaces. The goal is to make the structure of decompiled code less readable; it does not make an assembly impossible to reverse engineer.

It is distributed as a NuGet package and a .NET Global Tool, with a CLI deployment model. An XML file specifies which assemblies to process, dependency paths and the output location. That keeps configuration explicit, but places setup in the hands of developers rather than offering a graphical workflow.

Key features

Metadata renaming and smaller output

Obfuscar replaces identifiers with short names. Besides making code harder to follow, those shorter names can dramatically shrink executable size, a useful side effect for projects where assembly size matters.

String hiding

String hiding replaces string loads with calls that retrieve values from a buffer, at a small performance cost. The protection is reversible, so it is not suitable for confidential credentials or other secrets embedded in an assembly.

Configuration and integrations

XML configuration covers assemblies, dependencies and output paths. Community projects documented by Obfuscar can parse its mapping files or generate XML configuration for Unity, but those projects are unaffiliated; teams should treat them as separate tools rather than built-in support.

Pricing

The free plan covers the core obfuscation use case without a paid tier to step up to. It is a strong fit for individual developers and teams comfortable maintaining a command-line configuration. Community help is available through Stack Overflow and GitHub issues; commercial support is provided by LeXtudio Support Services.

Platforms

Obfuscar supports Linux, macOS and Windows, and its configuration guide provides path examples for all three. Version 3.0 beta requires absolute paths in configuration and rejects relative paths and variable placeholders, which can make existing or portable configurations harder to use.

Who it's for

Obfuscar fits .NET developers seeking a free way to make assembly metadata less legible as part of a CLI workflow. It is also worth considering when shorter identifiers could reduce executable size. It is not the right choice for anyone who needs obfuscation to stop a determined reverse engineer or wants to protect confidential strings inside an assembly.

Input handling needs care: malformed or malicious assemblies can cause unexpected behavior, including crashes or hangs. Process only trusted inputs.

Pros and cons

Pros

• Free, open-source core: the MIT-licensed plan provides basic .NET assembly obfuscation at no cost.
• Useful across desktop operating systems: Linux, macOS and Windows are supported, with platform-specific path examples.
• Potential size savings: shortened generated names can dramatically shrink executables as well as obscure metadata.

Cons

• Not a strong security boundary: obfuscation raises the difficulty of reverse engineering but cannot stop a determined effort.
• String hiding is reversible: it carries a small performance cost and should not be used to safeguard confidential values.
• Configuration constraints in 3.0 beta: absolute paths are required, while relative paths and variable placeholders are rejected.
• Untrusted inputs can be hazardous: malformed or malicious assemblies may crash or hang the tool.

Alternatives

Browse code obfuscation software for more options. For a different target or platform set, consider these alternatives:

• ByteHide Shield has a free tier for core obfuscation aimed at individual developers and small projects, plus paid plans for advanced techniques. Consider it if that tier structure or its broader listed platform support better matches your project.
• JS-Confuser is free and open source for JavaScript-focused needs; choose it instead when your target is JavaScript rather than .NET assemblies.
• ProGuard is a free, open-source shrinker for Java and Kotlin; choose it for those ecosystems instead of .NET.
• Tigress is another option to compare if its paid offering and trial suit your needs.
• yEd Graph Editor is a graph editor, not an assembly obfuscator.
• Garble is a free Go code obfuscator requiring Go 1.27 or later; choose it for Go projects.
• JavaScript Obfuscator offers a free plan with unlimited standard obfuscation, a 25 MB lifetime VM quota and a 4 MB VM file-size limit; choose it for JavaScript workflows that fit those limits.
• Obfuscator-LLVM is a Linux-only open-source LLVM fork; consider it for an LLVM-based workflow rather than .NET assemblies.

Verdict

Choose Obfuscar if you need a free, cross-platform CLI tool to make .NET assembly metadata harder to follow, with possible executable-size savings as a bonus. Look elsewhere if you need protection against determined reverse engineering, must keep strings confidential, or cannot work within its XML configuration and absolute-path requirements in the 3.0 beta.