Free security tools
Check your email security, score and triage vulnerabilities, and build scan commands, all free.
Accreditation Checker
Type a firm’s name or website and see whether it is on the CREST Marketplace or the NCSC CHECK register, with the register link and check date.
Open tool →Email securityEmail Security Checker
Check SPF, DKIM, DMARC, MTA-STS and DNSSEC for a domain in one go, with what to fix first and the exact records to publish.
Open tool →Email securitySPF Checker
See your SPF record, the 10-lookup count include by include, and how it ends. Get the record to publish when something is wrong.
Open tool →Email securityDKIM Checker
Find your DKIM key at the common selectors or your own, and check it is at least the recommended 2048 bits.
Open tool →Email securityDMARC Checker
Check your DMARC policy and reports, with SPF and DKIM alongside, and get the next record on the way from monitoring to reject.
Open tool →Vulnerability scoringCVSS 4.0 Calculator
Score a vulnerability with the current CVSS v4.0 standard — the FIRST MacroVector method. Base, threat, and environmental metrics; shareable vector.
Open tool →Vulnerability scoringCVSS 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 →HashingHash Identifier
Paste a hash and see the most likely algorithms — MD5, SHA-1, SHA-256, bcrypt, NTLM and more — ranked by likelihood, with every candidate shown when a shape fits several types.
Open tool →Web appJWT 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 →PasswordsPassword Strength & Crack-Time
Check password strength and estimated crack times across attacker scenarios. Your password stays in your browser.
Open tool →ReconnaissanceNmap 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 →NetworkingCIDR / 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 guidePentest Cost Calculator
Estimate a ballpark budget for a penetration test by type, scope, organisation size, and compliance driver: a rough planning range, shown as an estimate.
Open tool →AI securityMCP Config Checker
Paste an MCP config or tool list and check it for hidden instructions, invisible Unicode, servers with no authentication and wide file or shell access. Runs in your browser.
Open tool →AI securityAI Test-Plan Builder
Say how your AI system is built and get a test checklist mapped to the OWASP Top 10 for LLM Applications 2025, ready to paste into a quote request.
Open tool →AI securityPrompt-Injection Canary
A harmless test page: point your AI browser or agent at it and see whether it treats page text as an instruction.
Open tool →Need a penetration test, not just a tool?
Find firms that fit what you need tested, then scope the work and compare quotes with the buyer toolkit.