ZLB File

What are ZLB files and how to open them

Are you having problems opening a ZLB 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 ZLB files.

What is a ZLB file?

A .ZLB file is a Z-machine Game file.

A ZLB file is a package used by Z-machine interactive fiction games to bundle together all the resources needed to play, including the game's story code and optional media like sound, music, and images. It was created for text adventure-style games (also known as interactive fiction), so that a single file contains both the core story ("story file") and its supplementary resources. The ZLB files are produced when authoring or packaging interactive fiction games for the Z-machine engine, to simplify distribution and use.

The creator of ZLB files is Andrew Plotkin, who devised the Blorb format that underlies them. Blorb is a standardized wrapper format that stores both the Z-machine story file and associated media. When compiling or packaging a Z-machine game with resources, the author (using Blorb tools or authoring systems) produces a .zlb file so that interpreters can load the entire game in one go rather than requiring separate asset files. At runtime, a Z-machine interpreter such as Windows Frotz reads the .zlb file, extracts the story component, and plays the game, optionally also using the media inside it if supported.

Technically, ZLB is one of the file extensions used by the Blorb specification for Z-machine games. Blorb files are based on the IFF (Interchange File Format) container standard. ZLB files begin with the Blorb signature ("FORM IFRS") and include, among other chunks, a Z-code story chunk and various resource chunks (such as images, sounds, music) depending on what the game includes. The extension .zlb specifically denotes a Blorb file that contains a Z-machine story rather than a Glulx story.

How to open ZLB files

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

Programs that open Z-machine Game files

Last updated: August 14, 2026

Various apps that use files with this extension

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

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