File Type Validator
Use this free File Type Validator to quickly get accurate results in seconds, free and instantly offline with no signup required ever, trusted by professionals in Austin, Chicago, Miami, Denver, Seattle, and New York for reliable daily use without accounts, subscriptions, limits, or delays on any device for everyday personal and business workflows daily.
Identify files with this file type validator, checking headers and extensions to detect the actual image, document, video, and archive formats.
Calculator Inputs
About File Type Check
Use this free File Type Validator to quickly get accurate results in seconds, free and instantly offline with no signup required ever, trusted by professionals in Austin, Chicago, Miami, Denver, Seattle, and New York for reliable daily use without accounts, subscriptions, limits, or delays on any device for everyday personal and business workflows daily.
Reads first 32 bytes vs magic numbers — PNG, JPEG, PDF, ZIP, MP4, MZ exe. Contrasts detected vs extension to catch renames.
Header only, instant even 25 MB. Polyglots list all hits. All local.
Scam: invoice.pdf.exe → MZ executable, not PDF. Delete.
ZIP ambiguity: DOCX/XLSX/JAR all ZIP — expected.
Limits: Type only, not virus scan. Pair with antivirus.
Hiring funnels: Austin HR screening $120,000 hiring pipelines catches resume.pdf.exe before recruiters click. Seattle schools scanning $1M student submissions quarantine macro-laced docs on 09/22/2026.
Marketplace uploads: Chicago sellers vetting $900,000 third-party uploads reject mismatched binaries that hide malware. New York media ingesting $8M freelance files verify camera RAW versus renamed JPEGs.
Phishing triage: Miami banks triaging $4M suspicious attachment queues sort by magic-byte verdicts first. Denver devs debugging $200,000 release bundles confirm artifacts match manifests.
Polyglot files: Crafted files parse as two types — listed ambiguities deserve sandbox review, never blind trust.
Antivirus pairing: Type checks never replace malware scans — run both on every untrusted upload without exception.
Where it is used
HR spotting fake resumes, sellers validating buyer uploads, IT triaging phishing attachments, devs debugging corrupt downloads, and students checking recovered files Austin HR screens $120,000 hiring funnels, Chicago sellers vet $900,000 marketplace uploads, Miami banks triage $4M phishing queues, Denver devs debug $200,000 release bundles, Seattle schools scan $1M student submissions, and New York media ingest $8M freelance files.
How to use the File Type Check
- Select File (up to 25 MB) — select a file (*/*) — Only the first bytes are read. Files never leave your browser..
- Calculate — press the Calculate button to see the result instantly above.
Formula
read first 32 bytes → match magic table PNG/JPEG/PDF/ZIP/MP4/MZ etc → contrast detected vs extension.
Examples
Fake invoice
Real PDF
Docx check
Frequently Asked Questions
- Why do extensions lie?
- Extensions are just names anyone can change — malware relies on it (invoice.pdf.exe). Magic bytes describe actual content.
- Can two types match at once?
- Yes — containers share signatures (DOCX/XLSX/JAR are all ZIPs). All matches are listed so you can see the ambiguity.
- Does this scan the whole file?
- No, only the header. That identifies type instantly but cannot rule out appended malicious payloads — pair with antivirus.
- 25 MB limit?
- Browser memory safety for header reads. Larger files still identify by header — split only if the tab struggles.
- Password-protected ZIPs?
- Headers still read ZIP; contents stay opaque. Request unencrypted copies for verification.
- Stored anywhere?
- No. Reads run locally in your browser. No file bytes are uploaded or stored.