An extension such as .jpg, .pdf, or .docx is useful, but it is not proof of what a file contains. Extensions can be missing, incorrect, or deliberately misleading. Identification should combine several signals rather than relying on the last few letters of the filename.
Useful identification signals
- Filename extension.
- MIME type reported by the browser or operating system.
- Magic bytes or file signature at the beginning of the file.
- Readable text patterns such as JSON, XML, CSV, or source code.
- Container structure, for example ZIP-based DOCX or ODT packages.
- The source and context in which the file was received.
Unknown should also mean untrusted
If the file came from an unexpected email, download, message, or removable device, do not run executables, scripts, installers, macros, or unknown binaries merely to discover what they are. Use your operating system’s security tools and an approved malware-scanning workflow.
What File Opener can reveal
| Detected content | What Fitabyte can do | Limit |
|---|---|---|
| Image | Preview and offer image export | Depends on browser decoder support |
| Open in browser viewer | Viewer capabilities vary | |
| ODT/DOCX | Extract readable text | Does not reproduce full document formatting |
| Text-like file | Display readable content | Large or unusual encodings may be partial |
| Binary | Report that a visual/text preview is unavailable | Does not reverse-engineer proprietary formats |
Use File Opener for quick, local inspection when the file is from a source you trust. If the extension is HEIC, read the dedicated HEIC guide; for AVIF, use the AVIF guide.