BSW File

What are BSW files and how to open them

Are you having problems opening a BSW 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 BSW files.

What is a BSW file?

A .BSW file is a Bank Street Writer Dictionary file.

Bank Street Writer Dictionary files support the word-analysis tools of Bank Street Writer and its follow-on versions such as Bank Street Writer III. These files store a dictionary of correctly spelled words (the spelling dictionary) or synonyms (the thesaurus) which the program uses during spelling checks or synonym lookups. They allow words to be added by the user, resulting in an update dictionary file alongside the original base dictionaries.

The program Bank Street Writer III supplies two main dictionary files: DICTIONARY.BSW for spelling, and THESAURUS.BSW for synonyms. When a user adds new words via the spelling checker, an UPDATE.BSW file is created to store those additions, without modifying the original base dictionary. On disk systems with only one floppy, dictionaries are swapped in as needed; on systems with more disks or hard-drives, the user can set up where the program looks for these BSW files using its disk-location options.

These BSW dictionary files begin with a specific ASCII signature at the start of the file: the bytes spelling "BSWritercompressed dictionary" beginning at offset zero. That exact header identifies this format.

How to open BSW files

Important: Different programs may use files with the BSW file extension for different purposes, so unless you are sure which format your BSW 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 BSW openers which you will find listed below.

Last updated: August 25, 2026

Various apps that use files with this extension

These apps are known to open certain types of BSW files. Remember, different programs may use BSW 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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File.org helps thousands of users every day, and we would love to hear from you if you have additional information about BSW file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.