LIT File

What are LIT files and how to open them

Are you having problems opening a LIT file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your LIT files.

What is a LIT file?

LIT files have multiple uses, and Microsoft Reader eBook is one of them. Read more about the other uses further down the page.

Microsoft Reader eBook

The LIT file format is used by the Microsoft Reader software application and was initially released by Microsoft in 2000. Microsoft Reader is a free application that users can run to read eBooks on devices that run on the Windows operating system.

LIT files contain the actual contents of the digital book as well as book's digital rights information. This information limits the number of systems that each digital book can be read on, protecting the eBooks copyright.

How to open LIT files

We have identified two LIT openers that are compatible with this specific type of LIT file.

Programs that open Microsoft Reader eBook files

Last updated: August 7, 2026

All known file formats using extension .LIT

While Microsoft Reader eBook is a popular type of LIT-file, we know of 3 different uses of the .LIT file extension. Different software may use files with the same extension for different types of data.

Fractal Design Painter Lighting Lib

We know that one LIT format is Fractal Design Painter Lighting Lib. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

While we have not verified the apps ourselves yet, our users have suggested ten different LIT openers which you will find listed below.

Quake Colored Light Data

Quake Colored Light Data (.LIT) files hold precalculated colored lightmap information for levels in the Quake game, allowing modern source-ports to display colored lighting effects instead of the original monochrome lighting. These files are generated during map compilation when a level includes lights that specify RGB color values. The compiled data complements the BSP (binary space partition) map file and gets loaded by the game engine (or source port) at runtime to apply colored lighting to surfaces.

During map building, the LIGHT tool (often via compilers like ericw-tools or Tyrutils) produces a .LIT file alongside the .BSP whenever the map contains colored lights (e.g. light entities with a "_color" key). At game launch, source-ports check for a matching .LIT file named after the map; if present and valid, that file replaces or augments the standard greyscale lightmaps within the .BSP. If the .LIT file is missing or invalid, the engine falls back to traditional monochrome lighting.

The file begins with the ASCII signature "QLIT" followed immediately by version and other fields in little-endian format. One known implementation stores the number of surfaces ("numsurfs") in the header as a 32-bit little-endian value, matching the number of faces in the corresponding .BSP file. The total size of the file is expected to be equal to the number of lightmap data entries times three (for RGB) plus the size of the header.

LIT opener for Windows

We have identified one LIT opener that is compatible with this specific type of LIT file.

Various apps that use files with this extension

These apps are known to open certain types of LIT files. Remember, different programs may use LIT files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about LIT file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.