Estimate password strength from length, charset mix, entropy heuristics, and a short common-password list.
- Free
- No signup
- Fast
- Privacy-friendly
Free · API · MCPToolYour platform
Use Password Strength Checker three ways
The free Password Strength Checker on this page works in your browser. The same workflow is available via REST API for apps and via MCP for Cursor, Claude, and other agents — one API key, one plan, one quota. This tool is part of the security-apis module under Security Tools.
- Free in browserUse Password Strength Checker here — no account required.
- REST APICall from your server with
X-Api-Key. - MCP for agentsConnect Cursor or Claude to ToolYour MCP with the same key.
- 1. Get an API keySign in and open Dashboard → API Keys (works for REST and MCP).
- 2. Call or connectUse the REST API from your server, or paste the MCP URL into your agent config.
- 3. Same qualityOutput matches the free web tool across all three surfaces.
What is Password Strength Checker?
Estimate whether a password is trivially weak before you ship signup rules. ToolYour Password Strength Checker scores length, character classes, rough entropy, and a short common-password list. It is a heuristic — not a substitute for breach databases or server-side rate limits. REST/MCP POST with { "password": "..." }. Prefer not to paste real production passwords into public forms.
What are common questions about Password Strength Checker?
Do you store passwords I check?
Inputs are processed for the score only. Still avoid pasting real high-value credentials when you can use a similar test string.
What does the score mean?
A rough strength label (very-weak → strong) from length, charset mix, and entropy heuristics plus common-password hits.
What are the key features of Password Strength Checker?
Entropy estimate
Bits estimate from length × charset size for relative comparisons.
Actionable issues
Short checklist: length, case mix, digits, symbols, common list.
How do you use Password Strength Checker?
Enter a candidate password
Use a test string when evaluating policy, not a live vault secret.
Tighten policy
Prefer longer passphrases; pair with your secure password generator.
Policy tip
Length beats complex short passwords. Encourage passphrases and a password manager; enforce breach checks on your server.
Where do you browse more security tools tools?
- Security Tools tools
Browse the full Security Tools category on ToolYour.
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