How to Look Into a File

When you don't know what a file's type is and have no clues about what program works with a file it can sometimes help to look into the file and perhaps find clues in the file contents. Often all you will see will be binary bytes which translate to random characters in most viewers; but now and again you can find some hints within the file.

How you approach looking into a file will depend on what you are looking for.

ASCII/ANSI/Unicode

• FILExt's Online File Viewer

  Just open the file with our Online File Viewer to view your file's content online. The Online File Viewer also tells you the file type, which software was used to create the file, etc. and can convert your file to other formats.

• Editor

  If you want to see what text is in the file locally (without an internet connection), simply use the Windows Editor (Notepad), TextEdit on the Mac or the Linux Editor (under 'Accessories').

Binary files

Many files contain only binary data. For example, if you open a graphics file with a text editor, you will not see any readable text. You need a HEX editor to make any text visible:

• Online HEX editor

  With an online editor such as HexEd.it you don't need to install anything on your computer or smartphone.

• Offline HEX Editor

  To view binary encoded files locally on your computer, you can e.g. Hex Editor Neo (Windows), Hex Fiend (Mac) or xxd (Linux).

If you open a binary file in a HEX editor, you will see both the binary bytes (left column) and the translated ASCII equivalents (right column). If you're lucky, you'll find clues to the creator of the file for an unknown file:

When looking into files, pay particular attention to the first few characters in the file. There are some standard indicators for various common file types...

• If the first two characters are "BM" the file may be a .BMP bitmap image.

• If the first two characters are "PK" the file may be a .ZIP archive file.

• If the first two characters are "MZ" the file may be an .EXE executable file.

• If the first four characters are "%PDF" the file may be an Adobe .PDF file.

• ...and so on.

The Online File Viewer automatically examines a file for such standard indicators to determine the correct file format.

EXE, DLL, and Other Executables

While its unwise to attempt to edit an EXE, DLL or any other executable file many of these are compiled with resources as part of the file. You can use a resource viewer/editor to look at these resources and sometimes either extract them or even change them. (Again, changing anything in an executable file can render the entire program unavailable and if you change a system file your entire operating system could fail. Be careful!)

Here are a few resource viewers/editors:

• FileAlyzer (free - analysis but not editing)
• PE Explorer (paid)
• Resource Hacker (free)