IDX File

What are IDX files and how to open them

Are you having problems opening an IDX 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 IDX files.

What is an IDX file?

IDX files have multiple uses, and VobSub Subtitles Index is one of them. Read more about the other uses further down the page.

VobSub Subtitles Index File

Several DVD playback applications create files that contain the .idx file extension. These files contain information about the subtitles of a DVD, including the subtitle text and start points for when the subtitles should be shown.

The IDX file does not contain any actual video data. Instead, the video data is stored in an associated video file that is linked to the appropriate IDX file.

How to open IDX files

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

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

Last updated: August 7, 2026

All known file formats using extension .IDX

While VobSub Subtitles Index File is a popular type of IDX-file, we know of 9 different uses of the .IDX file extension. Different software may use files with the same extension for different types of data.

Amstrad PPC Organiser Index File

We know that one IDX format is Amstrad PPC Organiser Index File. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Clangd Index

We know that one IDX format is Clangd Index. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Foto-Mosaic-Edda Database Index File

We know that one IDX format is Foto-Mosaic-Edda Database Index File. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Java Applet Cache Index File

We know that one IDX format is Java Applet Cache Index File. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Norton Utilities Image Backup Index

We know that one IDX format is Norton Utilities Image Backup Index. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Parsons Technology Resource Index File

We know that one IDX format is Parsons Technology Resource Index File. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

TapEx Index

We know that one IDX format is TapEx Index. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

TheWord Bible Text Index File

TheWord Bible Text Index File (extension .IDX) is a cache/index file used by theWord Bible Software. It stores indexing data - or a searchable map - for a specific Bible or module loaded in theWord. Its purpose is to speed up operations such as looking up words, verses, or passages so that theWord doesn't need to re-scan the module text every time.

This file is generated and used behind the scenes by theWord when you load or use a Bible module. It is not a user-editable module itself, but a support file that helps the software present fast search results. If you remove the .IDX, the software will rebuild it next time the module is accessed and indexing is needed.

Technically the file begins with a fixed signature in ASCII: the first bytes at offset zero are "TWIDXBMOD". In hexadecimal, that is 54 57 49 44 58 42 4D 4F 44. This header identifies it uniquely as theWord Bible Text Index File, differentiating it from other .IDX-formats.

IDX opener for Windows

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

Various apps that use files with this extension

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