Legit Log C++ Library

Mature C++ logging library.


Legit Log C++ Library is a static lib to integrate into your projects, provided for free.

It is lightweight, simple to use, yet feature-rich and customizable.

Thousands copies of software are running with Log Library on board every day.


  • Comes with Log Viewer

    You don’t have to use Notepad-like tool to view log file. Log Viewer is extensible and not just dedicated to these specific files.

  • Thread-safe and process-safe

    We don’t use any hacks or tricky techniques. It is fully thread-safe on all supported platforms including multiprocessor configurations. Also, code is designed to work on other architectures even with weak memory model.

  • Unicode support

    Log files are written in Unicode encoding (UTF-16) to support all languages, even mixed together.

  • Application crashes invulnerable

    Log messages are written immediately directly to the disk, bypassing caches. This guaranties log will be consistent and will contain the last message even in case of application crash, BSOD or power failure.

  • Live capturing logs

    If encryption is not enabled, log messages are send via OutputDebugString API. They can be captured live in any compatible application like Legit Log Viewer, DebugView etc.

  • Optional log file encryption

    Log file can be encrypted to secure its content from editing or viewing using RSA and AES.

  • Low system resources usage

    Low resource usage is the primary goal. Log Library typically uses about 80KB of memory, unmeasurable amount of CPU time and drive remains fully responsive even when multiple processes log messages in loop.
    All required resources are allocated during first call.

  • Customizable

    You can customize logging levels, contexts, severities, encryption options and output path.
    Also, you can set filtering options to ignore messages with particular logging level or context.

System Requirements

Out-of-box library supports:

  • Visual Studio 2005, 2008, 2010 and 2012;
  • Windows XP or later operating system;
  • Itanium, x64 and Win32 process architectures;
  • native C++ and C++/CLI.

Other platforms and systems can be added on request, e.g. mobile, embedded, Xbox, etc. or by your own using version with source code.


Click to download Legit Log C++ Library.

Click to download Legit Log Viewer.

Additional Services

We offer support to help integrate Log Library into your projects or replace your current logging solutions.
Builds with custom compiler options etc. are provided too.


Using C++ Log Library screenshot

Using C++ Log Library

Referencing C++ Log Library screenshot

Referencing C++ Log Library

Log Viewer screenshot

Generic Log Viewer view

Manage keys screenshot

Manage encryption keys