Hash Lookup
Check whether an MD5, SHA-1, or SHA-256 hash matches a known common password or string. This lookup runs client-side and is meant for auditing known values, not guaranteed recovery.
Warning: This hash was found in a common password database. If this is a password hash, the password is extremely weak and should be changed immediately.
This hash was not found in our database of common passwords. This could mean the original value is a strong, unique string.
Paste a hash below to look it up
Lookup Hash
Checks against ~10,000 common passwords & strings. All processing happens in your browser.
How Hash Lookup Works
Hash functions are one-way - you can't mathematically reverse them to get the original input. A hash lookup checks your hash against a local table of known values, which is useful for spotting common passwords, copied sample hashes, and weak test data.
This tool loads a database of ~10,000 commonly used passwords and strings, computes their MD5, SHA-1, and SHA-256 hashes entirely in your browser using the Web Crypto API, and checks if your hash matches any of them. For broader background on recovery terminology, see the dehash tool.
Paste Hash
Enter any MD5 (32 chars), SHA-1 (40 chars), or SHA-256 (64 chars) hash.
Local Computation
Your browser computes hashes for all entries in the database and compares.
Instant Result
If a match is found, the original plaintext is revealed instantly.
Why Hash Lookup Matters
Hash lookup tools help security professionals and developers audit password strength. If a password hash can be reversed using a common dictionary, that password is dangerously weak.
- Penetration testing: Check if leaked hashes correspond to weak passwords
- Security auditing: Verify that your users aren't using common passwords
- Education: Demonstrate why MD5 and SHA-1 are unsuitable for password storage
- Incident response: Quickly identify compromised accounts with weak passwords
Hash Algorithm Comparison
| Algorithm | Output Length | For Passwords? | Lookup Difficulty |
|---|---|---|---|
| MD5 | 32 hex chars | Never | Very Easy |
| SHA-1 | 40 hex chars | Never | Very Easy |
| SHA-256 | 64 hex chars | Not ideal | Easy (for common inputs) |
| bcrypt | 60 chars | Recommended | Very Hard |
| Argon2 | Variable | Best | Extremely Hard |
Frequently Asked Questions
What is a hash lookup?
A hash lookup (reverse hash search) checks a hash value against a pre-computed database of hash-plaintext pairs. If your hash matches a known entry, the original plaintext is revealed. This is how attackers crack weak passwords — by using massive rainbow tables of common passwords.
Is my hash sent to any server?
No. Everything runs 100% in your browser. The common password list is loaded into memory, hashed locally using the Web Crypto API, and compared entirely client-side. Your hash never leaves your device.
Why can't it find my hash?
The tool checks against ~10,000 common passwords and strings. If the original value is unique, complex, or uncommon, it won't be in the database. This is actually a good sign — it means the password is not trivially crackable via dictionary attack.
Can this crack bcrypt or Argon2 hashes?
No. Bcrypt and Argon2 use unique salts for each hash, making pre-computed lookup tables useless. This is exactly why they're recommended for password storage. Only fast, unsalted hashes like MD5, SHA-1, and SHA-256 are vulnerable to lookup attacks.