Drag and drop a file to check it for viruses. Your file never leaves your device: we compute its fingerprint locally and check it against 1,045,564 known malware hashes.
Drop your file here or click to browse
Any file type · No size limit · Nothing is uploaded
Three steps. Zero uploads. Complete privacy.
Select or drag any file into the scanner — documents, installers, ZIP archives, even multi-gigabyte ISOs. It stays on your device the entire time; nothing is ever uploaded.
We calculate a unique MD5 hash of your file directly in your browser, reading it in small chunks so file size doesn't matter. This fingerprint identifies the file without revealing its contents.
Only the first 3 characters of the hash are used to fetch the matching slice of our malware database; the full match happens in your browser. You get an instant verdict. Have a hash already? Use the MD5 hash lookup.
Knowledge is your first line of defense against cyber threats.
Malware — short for malicious software — is any program or code designed to harm, exploit, or compromise a computer system, network, or user. Malware can steal sensitive data, encrypt files for ransom, spy on user activity, or turn devices into nodes in a botnet. It is delivered through email attachments, compromised websites, software downloads, and even legitimate-looking applications. Understanding the different forms of malware is essential for protecting your digital life.
Viruses attach to legitimate files and spread when those files are executed. Worms self-replicate across networks without user interaction. Trojans disguise themselves as legitimate software. Ransomware encrypts your files and demands payment. Spyware silently monitors your activity and harvests credentials. Adware bombards you with unwanted advertisements. Rootkits hide deep in the operating system to maintain persistent access. Each type requires different detection and remediation strategies.
The most common infection vector is phishing emails containing malicious attachments or links. Drive-by downloads exploit browser vulnerabilities when visiting compromised websites. Software bundling hides malware inside free applications. USB drives and removable media can carry infected files between air-gapped systems. Supply chain attacks compromise legitimate software updates. Social engineering tricks users into voluntarily installing malicious programs by disguising them as security tools, system updates, or popular applications.
Watch for sudden system slowdowns, unexplained crashes, or high CPU usage when idle. New toolbars, browser redirects, or pop-ups you didn't install are common indicators. Unexpected outbound network traffic, disabled security software, or locked files demanding ransom are serious red flags. Missing files, changed passwords, or unauthorized account activity suggest data theft. If your contacts report strange messages from your accounts, your system may be compromised and sending spam or phishing emails on your behalf.
Keep your operating system and applications updated with the latest security patches. Use a reputable antivirus solution and keep its definitions current. Never open email attachments or click links from unknown senders. Download software only from official sources. Enable multi-factor authentication on all accounts. Back up important files regularly using the 3-2-1 rule: three copies, two different media types, one offsite. Use tools like iMalware to verify suspicious files before opening them, and practice healthy skepticism toward unsolicited messages and too-good-to-be-true offers.
Hash-based malware detection works by computing a cryptographic fingerprint (hash) of a file and comparing it against a database of known malicious file hashes. This method is fast, accurate, and privacy-friendly because only the hash — not the file itself — needs to be transmitted. MD5, SHA-1, and SHA-256 are commonly used algorithms. While hash-based detection cannot identify zero-day threats or polymorphic malware that changes its signature, it remains one of the most reliable methods for identifying known threats and is used by security vendors worldwide as a first-pass detection layer.
Answers to the questions people ask most before opening a file.
Online, with Microsoft Defender, on a Mac or from the command line.
Hash lookup vs. upload scanners: privacy, size limits and accuracy.
A checklist for investigating an unknown or suspicious file.
Which file types can carry malware and how to open them safely.
Archives, password-protected ZIPs and the files inside.
Checking multi-gigabyte files with no size limit.
No. Your file never leaves your device. iMalware computes the MD5 hash entirely within your browser using JavaScript. Your browser then requests only the part of our database that matches the first 3 characters of the hash and compares the full hash locally, so we never receive your file or even its full hash.
Drag the file onto the scanner at the top of this page, or click it to choose a file. The result appears in seconds. For other methods, including Microsoft Defender's right-click scan and Mac commands, see our guide How to Scan a File for Malware.
An MD5 hash is a 128-bit fingerprint of a file, written as 32 hexadecimal characters. Even a single-byte change in a file produces a completely different hash. This lets us identify known malware by comparing fingerprints without analysing the file content itself.
Our malware signature database is updated daily with newly discovered threats from multiple intelligence feeds. This ensures you're checking against the most current known-threat data available.
No single tool can. iMalware uses hash-based detection, which is highly effective against known threats, but it cannot detect zero-day malware (never-before-seen threats) or polymorphic malware that changes its signature. For comprehensive protection, use iMalware alongside a full antivirus with heuristic and behavioural analysis, such as Microsoft Defender.
No. Files are read and hashed in small chunks inside your browser, so even multi-gigabyte files work. Speed depends on your device and disk; most files under 1 GB take a few seconds. See scanning large files.
Yes. iMalware checks the ZIP archive as a whole against known malware. It does not open the archive, so extract it to a folder (without opening the files) and drop the files inside to check each one. See how to scan a ZIP file for viruses.
No. iMalware runs in any modern browser on Windows, macOS, Linux, ChromeOS, Android and iOS. There is nothing to install and no account to create.
Don't open it. Delete it or let your antivirus quarantine it. If you already ran it, disconnect from the internet, run a full antivirus scan and change important passwords from a clean device.
Yes, iMalware is completely free to use with no limits on the number of scans. There are no premium tiers, no sign-up requirements, and no ads.
Bookmark iMalware and check any suspicious file before opening it. It takes seconds and could save you from a costly breach.
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