File Extension Checker Online – Check File Type & Format
Check a file's extension, format, file type, MIME type and size instantly with ZeroKB's free online File Extension Checker.
What Is a File Extension?
A file extension is the part of a filename that usually appears after the last dot and helps identify the file format. Common examples include PDF, JPG, PNG, DOCX, XLSX, MP4 and ZIP. ZeroKB's File Extension Checker helps you quickly identify the extension and basic information of a file.
How to Check a File Extension Online
Step 1: Select Your File
Click the file selection area and choose the file you want to check from your device.
Step 2: View File Information
After selecting a file, the tool displays its filename, extension, file type, MIME type and file size.
Step 3: Check the File Format
Use the displayed extension and file type information to understand the format of your selected file.
What Information Does the File Extension Checker Show?
ZeroKB's File Extension Checker can display several basic details about a selected file, including its file name, extension, detected category, MIME type and file size.
Common File Extensions
Some commonly used file extensions include PDF for documents, JPG and PNG for images, DOCX for Word documents, XLSX for spreadsheets, PPTX for presentations, ZIP for archives, MP3 for audio files and MP4 for videos.
More Useful File Tools on ZeroKB
After checking your file, you can use other ZeroKB tools depending on what you need to do with it.
Try our File Size Converter to convert file sizes between KB, MB and GB. You can also use Image Compressor to reduce image file size or Compress PDF to reduce the size of PDF documents.
Frequently Asked Questions About File Extensions
What is a file extension?
A file extension is the part of a filename that identifies or indicates the file format, such as PDF, JPG, PNG, DOCX or MP4.
How can I check a file extension?
Select your file using the ZeroKB File Extension Checker. The tool displays the filename, extension, detected file type, MIME type and file size.
Can I check different types of files?
Yes. The tool can identify many common file categories including PDF, images, documents, spreadsheets, presentations, archives, audio and video files.
What is a MIME type?
A MIME type is a technical identifier used by applications and browsers to describe the format or media type of a file.
Does the tool show the file size?
Yes. After selecting a file, the tool displays its size in an appropriate unit such as Bytes, KB, MB or GB.