BepInEx
BepInEx is a free, open-source plugin and modding framework for Unity Mono, Unity IL2CPP, and .NET Framework games, including those built with XNA, FNA, and …
What BepInEx is
BepInEx is a free, open-source plugin and modding framework for Unity Mono, Unity IL2CPP, and .NET Framework games, including those built with XNA, FNA, and MonoGame. It provides configuration and logging, runtime method patching, and in-memory assembly patching. Runtime patching uses Harmony, including HarmonyX and MonoMod; in-memory patching uses Mono.Cecil with UnityDoorstop. The installation guide lists Windows, Linux, and macOS, though supported versions and architectures vary by build and game. Setup is manual: download the correct build and place its contents in the game’s root folder. Official binaries are available as stable and bleeding edge builds; the documentation recommends stable builds in most cases and notes that bleeding edge builds tend to be buggier. Compatibility has limits: only Unity Mono has stable releases, and BepInEx 6 documentation is work in progress. BepInEx 5 is in long-term support, and its plugins do not yet work with the BepInEx 6.0.0 pre-release. User and developer guides cover setup, configuration, troubleshooting, and plugin development.
Good
- Supports Windows, Linux, and macOS.
- Includes configuration and logging tools.
- Provides runtime and in-memory patching.
- Open source under the LGPL-2.1 license.
Watch out
- Installation requires manual file placement.
- Only Unity Mono has stable releases.
- BepInEx 6 documentation is work in progress.
- BepInEx 5 plugins do not yet work with the 6.0.0 pre-release.
Who it suits
BepInEx suits players modding supported games and developers building game plugins. It is for users comfortable with manual installation and checking build compatibility.
Verdict
BepInEx provides mod-loading and patching capabilities across several game technologies, with guides for both users and plugin developers. Check the game’s engine and build compatibility, especially when choosing between BepInEx 5 and the BepInEx 6 pre-release.
Plans and prices
From BepInEx's own pricing page, checked 30 Sep 2026.
| Plan | Price | What it gives you |
|---|---|---|
| BepInEx | Free | open source · manual installation · stable and bleeding edge builds |
| BepInEx Free | Free | Stable releases · bleeding-edge builds · Unity Mono, IL2CPP and .NET/XNA framework game targets |
The facts
Each one read from BepInEx's own pages, with the date it was checked.
What it does
- Antivirus complaint
- A 2021 GitHub issue reports Norton deleting BepInEx.Preloader.dll as a threat, which the reporter associated with the loader's injection behavior.checked 15 Oct 2026
- Antivirus false positive
- A GitHub discussion records Gridinsoft flagging winhttp.dll and .doorstop_version in the 5.4.23.2 archive, with the reporter concluding it appeared benign after checking a related issue.checked 15 Oct 2026
- API documentation
- The API reference documents namespaces for core plugin classes, configuration, paths, bootstrap access and logging.checked 15 Oct 2026
- Assembly patching
- Mono.Cecil and UnityDoorstop enable in-memory patching of game assemblies.checked 15 Oct 2026
- Audience
- The docs provide instructions for installing BepInEx and writing plugins, indicating it is intended for people modding games and developing game plugins.checked 30 Sep 2026
- BepInEx 6 limitation
- The BepInEx 6.0.0-pre.2 release warns that BepInEx 5 plugins do not yet work with it and that the prerelease has many issues.checked 15 Oct 2026
- Bleeding-edge builds
- The builds site publishes platform-specific archives for Windows, Linux and macOS Unity Mono and IL2CPP, plus .NET Framework and CoreCLR targets.checked 15 Oct 2026
- Build channels
- Official binaries are available as stable builds and bleeding edge builds; the docs say stable builds are recommended in most cases and bleeding edge builds tend to be buggier.checked 30 Sep 2026
- Compatibility limit
- The repository says only Unity Mono has stable releases, and BepInEx 6 documentation is marked as work in progress.checked 30 Sep 2026
- Compatibility matrix
- The repository marks Unity Mono for Windows, macOS and Linux; Unity IL2CPP for Windows and Linux but not macOS; and .NET/XNA with Mono on macOS and Linux.checked 15 Oct 2026
- Configuration
- BepInEx includes a built-in configuration system for the framework and plugins.checked 15 Oct 2026
- Developer tooling
- The developer guide covers C# project setup, starter templates, logging, configuration files, preloader patchers and runtime method patching.checked 15 Oct 2026
- Drop-in installation
- The documentation lists drop-in installation as a core capability.checked 15 Oct 2026
- Ecosystem dependence
- PC Gamer says most Valheim mods require BepInEx and recommends installing its BepInExPack before additional mods.checked 15 Oct 2026
- Engine requirements
- Supported engines include Unity 3 or newer plus XNA, FNA, MonoGame and other .NET Framework engines.checked 15 Oct 2026
- Features
- It provides drop-in installation, built-in configuration and logging, runtime method patching, and in-memory assembly patching.checked 30 Sep 2026
- Game support
- The documentation lists Unity 3 or newer and .NET Framework games such as XNA, FNA, and MonoGame as supported game engines.checked 30 Sep 2026
- Independent listing status
- SourceForge hosts an exact mirror, states it is not affiliated with BepInEx, and shows 430 downloads in the reported week.checked 15 Oct 2026
- Installation
- BepInEx is installed manually by downloading the correct build and placing its contents in the game's root folder.checked 30 Sep 2026
- Installation method
- The official guide says installation is currently manual and requires choosing binaries for the game's runtime.checked 15 Oct 2026
- Latest stable release
- GitHub lists BepInEx 5.4.23.5 as the latest stable release and records fixes for Unity 2022.3.62f3, Doorstop 4.5.0 and Unity 6 logging.checked 15 Oct 2026
- Licence
- The GitHub repository identifies the BepInEx project licence as LGPL-2.1.checked 15 Oct 2026
- License
- The project is open source under the LGPL-2.1 license.checked 30 Sep 2026
- Limit: compatibility dependence
- Hysen Labs notes that plugin failures can follow game updates, runtime changes or obfuscation when targeted methods no longer exist.checked 15 Oct 2026
The full review of BepInEx
BepInEx is a free mod loader and plugin framework for supported Unity and .NET Framework games. It suits players installing mods and developers building plugins who are comfortable matching a build to a game and installing it manually. Its broad toolkit is useful, but engine and version compatibility should guide the choice.
Overview
BepInEx covers Unity Mono and IL2CPP, plus .NET Framework games built with XNA, FNA, or MonoGame. That makes it a flexible option across several game technologies, rather than a loader aimed at a single named title. The project is open source under the LGPL-2.1 license and provides user and developer guides, troubleshooting documentation, and a Discord server.
Installation is a manual file operation: download the build suited to the game, then place its contents in the game's root folder. The drop-in method is direct, but puts the responsibility for choosing the right build on the user. Stable and bleeding-edge builds are available; stable builds are recommended in most cases, while bleeding-edge builds tend to be buggier.
Key features
The framework combines mod loading with built-in configuration and logging, giving plugins shared basics without requiring every developer to build them independently. Runtime method patching uses Harmony, including HarmonyX and MonoMod. For in-memory assembly patching, BepInEx uses Mono.Cecil with UnityDoorstop. This range makes it useful to plugin developers who need more than a loader, although the right approach still depends on the target game and build.
BepInEx uses injection for mod loading and supports plugins, load-order control, and dependency handling. These capabilities help manage multiple plugins, but they do not remove the need to confirm that a specific game and plugin combination is compatible.
Compatibility is the main qualification. The documentation lists Unity 3 or newer and .NET Framework games among supported technologies, but stable releases are limited to Unity Mono. BepInEx 6 documentation remains work in progress; BepInEx 5 is in long-term support, and its plugins do not yet work with the BepInEx 6.0.0 pre-release. Users should check the game's engine and build before committing to a loader version.
Pricing
BepInEx
BepInEx costs nothing. The free, open-source plan includes manual installation and stable and bleeding-edge builds; there is no free trial because the software is free. There are no paid tiers to trade features against, so the practical cost is the time needed to select and install a compatible build.
Platforms
BepInEx supports Windows, macOS, and Linux. Supported operating-system versions and architectures vary by build and game, so platform support alone does not guarantee that a particular title will work.
Who it's for
BepInEx is a strong fit for players modding supported Unity or .NET Framework games and for developers who want plugin loading, configuration, logging, and patching in one framework. Its user and developer guides cover installation, configuration, troubleshooting, and plugin development. It is a less suitable choice for anyone seeking an automatic installer or a stable release for an engine other than Unity Mono.
Pros and cons
- Pro: Supports several Unity and .NET Framework game technologies, giving users and developers a broader target range than a loader tied to one named game.
- Pro: Built-in configuration, logging, runtime patching, and in-memory assembly patching provide useful foundations for plugin work.
- Pro: Free and open source, with Windows, macOS, and Linux support.
- Con: Manual installation requires users to choose a suitable build and place files in the game folder.
- Con: Stable releases are limited to Unity Mono, and the BepInEx 6 pre-release does not yet support BepInEx 5 plugins.
- Con: Bleeding-edge builds tend to be buggier, making them a riskier choice when stability matters.
Alternatives
For a broader comparison, see the Game Mod Loaders category. MelonLoader is another free option for Windows, macOS, Linux, and Android. Choose SMAPI if you need its Stardew Valley focus and meet its requirement of Stardew Valley 1.6.14 or later on Linux, macOS, Windows, or Steam Deck.
Satisfactory Mod Loader is a free choice for Satisfactory, with Windows client and server support and Linux server support. ModTek is a free mod loader for the BattleTech PC game. For Cyberpunk 2077, RED4ext provides a free script extender and plugin manager, while Cyber Engine Tweaks offers a free framework on Linux and Windows.
Hell2Modding is another free option for macOS and Windows. MWSE is free software under the GNU GPL for Linux and Windows, and welcomes contributions including ideas, bug fixes, documentation, and features.
Verdict
Choose BepInEx if you want a free, capable plugin framework for a supported Unity or .NET Framework game and are prepared to install the matching build yourself. Its combination of loader, developer tools, and broad technology support is the main reason to choose it. Look elsewhere if your game is outside its compatibility range, you need stable support beyond Unity Mono, or you depend on BepInEx 5 plugins while considering the BepInEx 6 pre-release.
Getting started
- Open the BepInEx project page.
- Identify the build compatible with the game and operating system.
- Download the selected stable or bleeding-edge build.
- Place the downloaded build contents in the game's root folder.
- Use the guides for configuration, troubleshooting, or plugin development.
Limits worth knowing
BepInEx is free and offers stable and bleeding-edge builds. Only Unity Mono has stable releases; BepInEx 6 documentation is work in progress, and BepInEx 5 plugins do not yet work with the 6.0.0 pre-release.
Questions
How much does BepInEx cost?
BepInEx is free and open source under the LGPL-2.1 license.
Which games does it support?
Its documentation lists Unity 3 or newer and .NET Framework games, including XNA, FNA, and MonoGame. The framework also supports Unity Mono and Unity IL2CPP games.
Which operating systems are supported?
The installation guide lists Windows, Linux, and macOS. Supported versions and architectures vary by build and game.
How do I install it?
Download the correct build and place its contents in the game's root folder.
Are stable builds available?
Official binaries include stable and bleeding-edge builds. The documentation recommends stable builds in most cases and says bleeding-edge builds tend to be buggier.
What are the compatibility limits?
Only Unity Mono has stable releases, and BepInEx 6 documentation is marked as work in progress. BepInEx 5 plugins do not yet work with the BepInEx 6.0.0 pre-release.
Alternatives to BepInEx
- 1
MelonLoader
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Satisfactory Mod Loader
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SMAPI
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RED4ext
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ScriptHookVDotNet
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