MD5 Hash Generator

Generate MD5 hashes from any text. See the 128-bit digest in hex or base64. Everything runs in your browser — nothing is transmitted.

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hash — md5
guest@pwgen:~$ hash md5 --encode=hex
hash output appears here — one hash per line
encoding
[init] md5 hash engine — ready
[info] all hashing runs client-side · your data never leaves the browser

What Is MD5?

MD5 (Message-Digest Algorithm 5) is a cryptographic hash function designed by Ronald Rivest in 1991. It takes any input and produces a fixed 128-bit (16-byte) hash value, typically rendered as a 32-character hexadecimal string.

MD5 was widely used for verifying data integrity and storing password hashes. However, serious vulnerabilities were discovered starting in 1996, and practical collision attacks were demonstrated in 2004. Today, MD5 is considered cryptographically broken and unsuitable for security-critical applications — but it remains useful for non-security checksums.

MD5 Security Status

Use CaseSafe?WhyAlternative
Password HashingNoRainbow tables crack common passwords instantlybcrypt, Argon2
Digital SignaturesNoCollision attacks can forge signaturesSHA-256, SHA-512
SSL CertificatesNoExploited by Flame malware in 2012SHA-256
File ChecksumsYesAccidental corruption detection is fineSHA-256 (preferred)
Cache KeysYesNo security requirement, fast computation
Data DeduplicationCautionWorks for low-stakes dedup, not adversarialSHA-256

MD5 collision attacks are practical and well-documented. Never rely on MD5 where an adversary could craft malicious inputs.

Common MD5 Use Cases

File Checksums

MD5 is still widely used to verify file downloads haven't been corrupted during transfer. While not secure against intentional tampering, it reliably detects accidental bit errors and incomplete downloads.

Data Deduplication

Storage systems use MD5 to quickly identify duplicate files by comparing hashes instead of entire file contents. For non-adversarial environments this offers a fast, space-efficient comparison method.

Cache Keys

Web servers and CDNs generate MD5 hashes of content to create unique cache identifiers. The speed of MD5 makes it practical for high-throughput caching where security isn't a concern.

Legacy Systems

Many older applications, APIs, and protocols still require MD5 hashes for backward compatibility. Gravatar uses MD5 hashes of email addresses, and some package managers still publish MD5 checksums alongside newer algorithms.

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Frequently Asked Questions

Is MD5 still secure?

No. MD5 is cryptographically broken — collisions can be generated in seconds. It should never be used for password hashing, digital signatures, or SSL certificates. It remains useful for non-security checksums like file integrity verification and cache key generation.

Can an MD5 hash be reversed?

MD5 is a one-way function — you cannot mathematically reverse it. However, attackers use precomputed rainbow tables and brute-force searches to find inputs that match common hashes. Short or common strings are trivially crackable.

What is an MD5 collision?

A collision occurs when two different inputs produce the same MD5 hash. In 2004, researchers demonstrated practical collisions, and by 2012, the Flame malware exploited MD5 collisions to forge Microsoft code-signing certificates.

What should I use instead of MD5?

For checksums, use SHA-256 or SHA-512. For password hashing, use bcrypt, scrypt, or Argon2. For digital signatures and certificates, use SHA-256 or SHA-3. There is no modern security use case where MD5 is the right choice.

Why does my MD5 hash always have 32 characters?

MD5 produces a fixed 128-bit (16-byte) digest. When encoded in hexadecimal, each byte becomes 2 hex characters, resulting in exactly 32 characters regardless of input length.

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