CLX File

What are CLX files and how to open them

Are you having problems opening a CLX 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 CLX files.

What is a CLX file?

A .CLX file is a Sentry Spelling-Checker Engine Lexicon file.

The Sentry Spelling-Checker Engine lexicon format is a binary lexicon used by Wintertree Software's Sentry Spelling-Checker Engine (SSCE) to store a compressed, read-only collection of words that serve as the main dictionary in spelling checks. Main lexicons are not modified at runtime; user or temporary lexicons are handled separately.

These lexicons are produced by SSCE tools such as SqLex ("compressed (.clx) lexicon files") or related utility programs that build and compress word lists. The runtime lexicon is loaded by the Sentry Spelling-Checker Engine by name via API calls or via configured file lists (e.g. MainLexFiles). The engine uses them to check whether words are correctly spelled and to generate suggestions for misspellings.

Sentry's lexicons come in two main types: compressed (.clx) lexicons, and text (.tlx) lexicons. The compressed lexicons are used for efficiency and to reduce memory and disk usage; they are binary and cannot be directly edited. For applications or lexicon updates, word lists are maintained in text lexicons which can then be converted or compressed into .clx as needed.

A lexicon file begins with an ASCII signature of SSCELexicon at offset 0, followed by specific copyright and vendor identification strings including "COPYRIGHT (C)" and "WINTERTREE SOFTWARE INC." located at exact offsets (e.g. copyright starts at byte 46, vendor name around byte 66).

How to open CLX files

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

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

Last updated: August 31, 2026

Various apps that use files with this extension

These apps are known to open certain types of CLX files. Remember, different programs may use CLX 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 CLX file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.