BOO File

What are BOO files and how to open them

Are you having problems opening a BOO 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 BOO files.

What is a BOO file?

BOO files have multiple uses, and Boogle Lexicon is one of them. Read more about the other uses further down the page.

Boogle Lexicon

Boogle Lexicon files store the word list (lexicon or dictionary) used by the shareware DOS word-game Boogle, developed by Seaboard Software. These files are used by the game to determine valid words players may enter, and are part of the game's data resources rather than its executable logic.

These files are created by Seaboard Software's Boogle game and read by the same game during play. The game loads a Boogle Lexicon file to supply the complete list of valid words and their spellings so that it can check each word the player enters against this list.

The format begins with a recognizable ASCII header: the first bytes indicate "Boogle Lexicon File" followed by a copyright notice such as "Copyright (c) 19…" at offset zero, and then the text "by Seaboard Software" shortly after. These identifiers help the game detect and verify the correct lexicon among its data files.

The file contains primarily a list of words in plain or simple encoded ASCII as required by the DOS environment in which the game runs. There is no public detailed specification of internal indexing, compression, or additional metadata beyond the header and word list that could be verified.

How to open BOO files

Important: Different programs may use files with the BOO file extension for different purposes, so unless you are sure which format your BOO file is, you may need to try a few different programs.

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

Last updated: August 24, 2026

All known file formats using extension .BOO

While Boogle Lexicon is a popular type of BOO-file, we know of 2 different uses of the .BOO file extension. Different software may use files with the same extension for different types of data.

IBM BookManager Book

A BookManager Book is an electronic document produced by IBM's BookManager software. It is designed to hold structured content that resembles a printed book, with elements like a cover page, table of contents, chapters, and an index. It is useful for publishing, browsing, and searching product manuals, reference guides, or other multi-topic texts, especially in IBM's documentation systems.

The format is generated by BookManager BUILD tools, which convert source content into a Book format that can be read or searched with IBM's BookManager READ programs or IBM's Softcopy Reader. The documents are stored in a repository or Books directory, often grouped in bookshelves for cataloging and cross-book search functionality. The indexed search inside each book and across bookshelf collections is supported via built-in book-level indexes and, for larger collections, separate bookshelf search index files.

A technical identifier: these Book files have file names ending in the .boo extension. They begin with recognizable internal signatures such as repeated '@' characters (for example bytes 0x404040 at offset 41, ASCII "@@@") and contain visible separator strings like a line of dashes ("-----------------"). These distinctive byte patterns differentiate the BookManager Book format from other uses of the same extension.

Various apps that use files with this extension

These apps are known to open certain types of BOO files. Remember, different programs may use BOO 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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