Skip to content
TechnologyTools

Security

Text Entropy Analyzer

Measure the Shannon entropy of any text or password — bits per character, total bits, and a plain-language strength assessment.

Computed locally with Shannon’s formula (−Σ p·log₂ p). Nothing is stored, logged, or sent anywhere.

Entropy Measures the Process, Not the String

The number this tool computes is the entropy of the generation process: how many equally likely possibilities the generator had. A password like "Tr0ub4dor&3" typed by a human scores well on character-class heuristics but came from a process with far fewer possibilities than its symbol count suggests. This is why password managers, which generate from a uniform random process, beat human-crafted passwords of the same length — and why the honest metric here is bits, not character classes.

How the Entropy Number Is Computed

  1. Paste a password or any text — processing is local and nothing is stored.
  2. Character frequency analysis computes the Shannon entropy per character.
  3. Charset detection estimates the entropy rate the password *uses* (lowercase only vs full mixed set).
  4. The verdict panel translates the numbers into practical strength guidance.
Formula & Technical Standard
Shannon: H = −Σ p·log₂(p) per symbol. Password entropy estimate: length × log₂(charset size).

Example: Comparing Two Passwords

Repetitive password
Input: aaaaaaaaaaaaaaaa1234
Output: Low effective entropy despite length
Length alone does not create entropy — repetition collapses it. The tool quantifies why.
Random passphrase
Input: Mixed-case 16-char random string
Output: ≈ 104 bits — very strong
Full-charset random strings maximize entropy per character; the estimate confirms the policy target.

Common Questions

Is entropy the same as password strength?

Entropy measures unpredictability. It is the best single metric for randomly generated secrets, but human-chosen passwords also need pattern checks (dictionary words, leetspeak) beyond raw entropy.

Is my password uploaded?

No. Everything is computed locally; the input never leaves your browser.

Securitypopular

Secure Password Generator

Generate cryptographically secure passwords locally via crypto.getRandomValues() with accurate real-time entropy scoring and zero server transmissions.

Security

Cryptographic Hash Generator

Compute secure cryptographic message digests client-side using native window.crypto.subtle and pure JS MD5 with legacy safety indicators.

Security

Random String Generator

Generate cryptographically secure random strings for tokens, IDs, and keys — with full control over length and character sets.