Frequently Asked Questions

VB Decompiler analyzes programs written in Visual Basic 5.0/6.0 and .NET (C#, VB.NET). It can restore source code (decompilation), disassemble native code, recover forms and user controls (.frm, .ctl), and allow you to edit string constants.

VB Decompiler combines privacy, native performance, and long-term reverse-engineering expertise:

• Completely private offline analysis. Core decompilation and analysis run entirely on your computer. VB Decompiler does not upload analyzed files or decompiled data to DotFix Software servers, so you can safely use it with the network disconnected. The optional AI Helper can also work with local models.
• Fast native implementation. VB Decompiler is written using a fast native programming language (Delphi) and compiles directly to machine code without an intermediate bytecode, managed runtime, or wrapper-based execution. Its decompilation engines do not depend on third-party libraries or frameworks. This purpose-built native implementation delivers consistently high performance even on modest hardware.
• Human-engineered core algorithms. The code behind all key product algorithms was designed without AI-generated code. Operations that other solutions may implement as pipelines with dozens of processing passes are handled by carefully designed two-pass algorithms in VB Decompiler, significantly reducing processing time.
• 21 years of continuous product development and more than 25 years of practical expertise. While many competing desktop solutions saw little or no public development after the early 2000s, VB Decompiler continued to evolve steadily. This accumulated expertise has made the product fast and straightforward to use, while its apparent simplicity is backed by years of highly specialized research, sophisticated decompilation engines, and carefully refined algorithms.
• Technical support seven days a week. We answer our customers every day, including weekends and public holidays. Holiday calendars and working weeks differ between countries, so our customers do not have to schedule urgent recovery or analysis work around another country’s business days. This availability has often helped clients keep important work moving when timely assistance mattered most.
• Tested in virtualized and compatibility-layer environments. Unlike competing products, VB Decompiler is routinely tested with Wine, Parallels, and Proton. Customers—including antivirus companies—can use it in these environments as a supported scenario rather than relying on unverified compatibility.

Yes, it supports all standard compiled binary types: EXE (Executables), DLL (Dynamic Link Libraries), and OCX (ActiveX Controls) for both VB6 (P-Code, Native Code) and .NET (C# and Visual Basic) platforms. For deep technical knowledge, see our VB 6.0 reverse engineering guide

For .NET applications, yes — full support for x86 and x64 assemblies.
For Visual Basic 6.0, only 32-bit files are supported (since VB6 never produced 64-bit code).

No. VB Decompiler is specialized for Visual Basic 5.0 / 6.0 and C# .NET. If you try to open a Delphi or C++ file, it will warn you that the format is unsupported. However, we have internal tools for Delphi/FreePascal and offer this as a separate service. Just email us.

Success depends on compilation type:

• P-Code (VB6): High success rate (up to 85%). Logic is mostly restored.
• .NET (C#/VB.NET): Very high success rate (up to 95%). Code is decompiled into readable C#.
• Native Code (VB6): Medium success rate, hardest to decompile. You get a partially recovered Visual Basic code (up to 75% recovery).

The AI Helper (available in v12.6+) uses a LLM models in a local network (using Ollama with models like Qwen3) to post-process decompiled code. It can rename variables based on context, convert Goto jumps into While/For loops, and generally clean up the syntax. It requires a GPU with 8GB+ VRAM for best performance.

By default, VB Decompiler processes the entire file at once. For large projects, this takes time. "Fast Decompilation" mode processes only the procedures you explicitly open, making the tool work instantly even on huge files. You can toggle this in Options -> Advanced features.

In most cases, no. Compilers strip variable names to optimize file size. You will see generic names like var_10, etc. However, Forms, Controls, standard Events, and Public functions usually retain their original names.

Tracing lets you emulate the execution of any functions from the compiled VB6 program without running it. You can step through instructions, watch register values (EAX, EBX...), and see stack changes. This is safer than running malware in a debugger.

Yes. Use Tools -> String References to find all text strings. You can edit them directly. Note that the new string length cannot exceed the original length (due to binary file structure limitations).

Yes! You can export analyzed data (procedure names, entry points) to MAP files, IDC scripts (for IDA), or NAMET files (for HIEW). This helps you continue analysis in other debuggers and disassemblers.

VB Decompiler includes a generic 32bit unpacker only for simple packers (like UPX) and it works only in a 32bit version of Windows. If a file is packed, it will attempt to unpack it automatically. However, it can't help for custom packers or for a protected files.

• Single Developer License: For 1 person. Installation on 1 PC (physical or virtual) allowed. This license assigns to the developer' name and can't be transferred between developers or used by anyone other than the owner.
• Enterprise License: For companies. Installation on up to 20 PCs (physical or virtual) allowed. Using by up to 20 developers. If you require activating software on more than 20 PCs (or use by more than 20 employees), you need to procure additional licenses for these devices.

Both allow commercial use.

No. The Educational license is strictly for non-commercial home learning. It prohibits decompiling commercial / copyrighted software, malware analysis, and commercial usage.

Your license is perpetual for the version you purchased. You can keep using already installed software forever. But only on the PC where you activated it during the active license subscription. The subscription covers access to new updates and technical support. The subscription also allows you to move the license to a new PC. You can renew your license at a discount price.