Common file extensions
Extensions are only hints, not proof — malware often disguises itself with a familiar one.
| Ext | Usually means |
|---|---|
| Portable document | |
| .doc / .docx | Word document |
| .xls / .xlsx | Excel spreadsheet |
| .ppt / .pptx | PowerPoint |
| .txt | Plain text |
| .csv | Comma-separated values |
| .json | JSON data |
| .xml | XML data |
| .html / .htm | Web page |
| .css | Stylesheet |
| .js / .mjs | JavaScript |
| .ts | TypeScript / video transport stream |
| .py | Python source |
| .java | Java source |
| .zip / .rar / .7z | Archive |
| .gz / .tar | Compressed / tape archive |
| .exe / .msi | Windows program / installer |
| .dmg / .pkg | macOS disk image / package |
| .apk | Android package |
| .ipa | iOS app package |
| .mp3 / .wav / .flac | Audio |
| .mp4 / .mov / .mkv | Video |
| .png / .jpg / .webp | Image |
| .svg | Vector image |
| .psd | Photoshop |
| .ai | Illustrator |
| .sql | SQL script / dump |
| .log | Log file |
Notes
- .ts can mean TypeScript or MPEG transport stream — context matters.
- Double extensions like .pdf.exe are a classic malware trick.
Frequently asked questions
- What is a .json file and how do I open it?
- A .json file stores structured data in JavaScript Object Notation, plain text that humans can read. Open it with any text editor; browsers and devtools also display it.
- What file extension is .exe?
- .exe is a Windows executable — a program or installer. Only run .exe files from trusted sources, as they can execute any code on your PC.
- What is the difference between .doc and .docx?
- .doc is the old binary Word format, while .docx is the newer Office Open XML format used since Word 2007. .docx files are smaller and open in more apps.