Free Online Cybersecurity Tools
A comprehensive collection of free, client-side cybersecurity utilities designed for security professionals, developers, and enthusiasts.
Why SecurityTools.dev
Built for developers, by developers
Every tool runs entirely in your browser — no data is sent to any server. Privacy is not a feature, it is the foundation.
100% Client-Side Processing
Your data never leaves your browser. All operations run locally for maximum privacy.
Completely Free
No subscriptions, no limits, no hidden fees. Every tool is free forever.
Fast & Reliable
Instant results with no server round-trips. Works offline once loaded.
Mobile Friendly
Fully responsive layout that works seamlessly on any screen size.
Open Source
Fully transparent codebase. Audit, fork, or contribute on GitHub.
Dark / Light Mode
Choose your preferred theme. Your eyes will thank you at 2am.
The Toolkit
28 tools available
Browse our growing collection of client-side security and developer tools. More tools are added regularly.
Password Generator
Generate strong, random passwords with custom rules.
Password Strength Checker
Analyze password strength and entropy score.
Base64 Encoder/Decoder
Encode and decode Base64 strings instantly.
URL Encoder/Decoder
Encode or decode URL components safely.
Hex Converter
Convert text or numbers to and from hexadecimal.
HTML Entity Encoder
Encode special characters as HTML entities.
Hash Generator
Generate MD5, SHA-1, SHA-256 and more.
Hash Identifier
Identify hash types from an unknown hash string.
Checksum Verifier
Verify file integrity using checksums.
IP Lookup
Get geolocation and ASN info for any IP address.
DNS Lookup
Query DNS records for any domain.
Whois Lookup
Retrieve domain registration information.
Port Scanner Info
Reference guide for common network ports.
Text Encryptor/Decryptor
Encrypt and decrypt text with a passphrase.
AES Encryption Tool
AES-256 encryption and decryption tool.
Regex Tester
Test and debug regular expressions in real-time.
JWT Decoder
Decode and inspect JSON Web Tokens.
CSP Builder
Build and validate Content Security Policy headers.
UUID Generator
Generate v4 UUIDs instantly.
Random String Generator
Generate cryptographically random strings.
Cron Expression Generator
Build and validate cron expressions visually.
Timestamp Converter
Convert Unix timestamps to human-readable dates.
Color Picker & Converter
Convert colors between HEX, RGB, HSL and more.
HTTP Header Analyzer
Analyze HTTP response headers for security and performance.
Email Header Analyzer
Parse and inspect raw email headers: SPF, DKIM, DMARC, relay hops, and security warnings.
URL Parser / Subdomain Extractor
Parse a URL into protocol, hostname, subdomain, domain, public suffix, port, path, and query params.
IP / CIDR Calculator
Compute network address, broadcast, subnet mask, host counts for IPv4 CIDR, plus IP-in-subnet check.
Password Leak Check
Check if a password has appeared in known data breaches via Have I Been Pwned (k-anonymity).