Free security tools

Fast, accurate tools for the day-to-day work of testing and triaging vulnerabilities. No sign-up, no adverts, no tracking — each one runs entirely in your browser, so nothing you paste or type ever leaves your machine.

Vulnerability scoring

CVSS 4.0 Calculator

Score a vulnerability with the current CVSS v4.0 standard — the official FIRST MacroVector algorithm, verified against the reference. Base, threat, and environmental metrics; shareable vector.

Open tool →Vulnerability scoring

CVSS 3.1 Calculator

Score a vulnerability against the FIRST CVSS v3.1 specification. Set base, temporal, and environmental metrics; get the score, severity, and a shareable vector string.

Open tool →Hashing

Hash Identifier

Paste a hash and see the most likely algorithms — MD5, SHA-1, SHA-256, bcrypt, NTLM and more — ranked by likelihood, and honest when a shape maps to several types.

Open tool →Web app

JWT Decoder

Decode a JSON Web Token to inspect its header, payload, and claims, with expiry checked and humanised. Decode-only — the signature is never required.

Open tool →Passwords

Password Strength & Crack-Time

Check password strength with honest crack-time estimates across attacker scenarios. Transparent entropy model; your password never leaves the browser.

Open tool →Reconnaissance

Nmap Command Builder

Pick a scan type, ports, timing, and detection options and get a valid nmap command with every flag explained in plain English.

Open tool →Networking

CIDR / Subnet Calculator

Enter an IPv4 block for the full breakdown — network and broadcast addresses, netmask, wildcard mask, usable host range, and host count. Handles /31 and /32.

Open tool →Buyer’s guide

Pentest Cost Calculator

Estimate a ballpark budget for a penetration test by type, scope, organisation size, and compliance driver — an honest range based on typical UK day rates.

Open tool →

How our tools work

Private by design. Everything runs client-side in your browser. We do not receive, log, or store anything you enter.
Standards-accurate. Where a tool implements a published standard, it follows the specification exactly and is tested against known reference values.
No account, no cost. Free to use and free to link to or share via the URL.

Need a penetration test, not just a tool?

Our independent directory lets you compare UK penetration testing companies by service, accreditation, and size — sourced from public records, never pay-to-play.

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