Prof. Noah Klein
"The Privacy Guardian"
Cybersecurity Researcher & Privacy Advocate
Professor Klein holds a PhD in Information Security and has testified before EU parliamentary committees on data privacy legislation. He builds encryption tools for journalists, audits web applications for security flaws, and believes that privacy isn't a feature — it's a fundamental right. His research has been cited in Wired, Nature, and The Guardian.
54 tools by Prof. Noah
Base64 Encode / Decode — Convert any text to Base64, or decode Base64 back to readable text. Full unicode support.
URL Encoder / Decoder — Encode or decode URL strings — single component or full URL — with proper percent-encoding.
HTML Entity Encoder / Decoder — Convert text to safe HTML entities, or decode entities back to characters. Minimal, named, or numeric output.
Hash Generator — Hash any text with MD5, SHA-1, SHA-256, SHA-384, or SHA-512 — all client-side via Web Crypto.
Binary ↔ Text Converter — Convert any text into binary (UTF-8 encoded), or decode binary back to text. Runs entirely client-side inside your browser.
ROT13 / Caesar Cipher — Apply a Caesar shift to text. ROT13 is the famous self-inverse version. Useful for puzzles, spoilers, light obfuscation.
Morse Code Translator — Translate text to and from International Morse Code — dots, dashes, slashes between words.
Hex ↔ Text Converter — Convert text to hexadecimal bytes (UTF-8) or decode hex back to text. Forgiving input — ignores 0x prefixes, commas, and spaces.
ASCII Codes Converter — Turn text into a list of ASCII or Unicode code points in decimal or hex — and convert code points back into text.
Base32 / Base58 Encoder & Decoder — Encode and decode Base32 (RFC 4648), Base32-hex, and Base58 (Bitcoin / IPFS). Sister tools to our Base64 encoder.
Punycode Converter — Convert between Punycode (ASCII-safe encoding) and Unicode domain names. Essential for working with internationalized domain names ...
Free online DNS lookup tool. Query A, AAAA, CNAME, MX, NS, TXT, SOA, and CAA records for any domain using Google DNS-over-HTTPS.
Free online WHOIS lookup tool. Check domain registration details, registrar info, expiry dates, name servers, and DNSSEC status.
Free online ping tool. Measure HTTP round-trip latency to any URL with min, max, average response times and packet loss statistics.
Free online HTTP headers checker. View all response headers from any URL including security headers, caching, content type, and CORS settings.
Free online SSL certificate checker. Verify SSL/TLS certificate details for any domain including issuer, expiry date, validity, and serial number.
Free online IP address lookup tool. Get geolocation, ISP, timezone, and ASN details for any IP address. Also supports your own IP detection.
My IP Address — Instantly detect your public IP address along with city, region, country, ISP, timezone, and ASN.
Free online URL redirect checker. Trace redirect chains, view HTTP status codes, and see the final destination URL for any link.
Bcrypt Generator — Generate bcrypt password hashes with a configurable cost factor. Enter a password and get a secure bcrypt hash instantly.
Free online ASCII converter. Convert text to decimal, hex, octal, and binary ASCII codes and back. Includes full ASCII character reference table.
Binary Converter — Convert numbers between binary, decimal, octal, and hexadecimal bases. Runs entirely client-side inside your browser.
Octal Converter — Convert octal numbers to decimal, hexadecimal, and binary. Runs entirely client-side inside your browser.
Free online HTML entity converter. Encode text to named, decimal, or hex HTML entities and decode entities back to text.
IDN Punycode Converter — Convert internationalized domain names (IDN) to Punycode (xn-- format) and back. Runs entirely client-side inside your browser.
Text Encryptor — Protect your private messages and sensitive data with secure password-based encryption. Encrypt to cipher text and decrypt it back inst...
Check a domain's MX mail servers, SPF record, and DMARC policy in seconds. Instant green/red status for each email deliverability record.
Check DNS propagation in real time using Google and Cloudflare public resolvers. See if your A, CNAME, MX, TXT or other records agree worldwide.
Generate SPF, DMARC, and DKIM DNS TXT records for your domain in seconds. Set allowed IPs, include domains, policy, reports, and selector.
Enter any IPv4 CIDR block to instantly get the network address, broadcast, usable host range, subnet mask (dotted + binary) and wildcard mask.
Encrypt and decrypt messages with PGP right in your browser. Generate RSA 4096 key pairs. 100% client-side — keys never leave your device.
Generate BIP39 mnemonic seed phrases for cryptocurrency wallets. 12 or 24 words from the official BIP39 wordlist. Client-side only.
Generate RSA public and private key pairs in PEM format using the Web Crypto API. Choose key size and export format. Client-side only.
Generate TOTP one-time passwords from a secret key. Compatible with Google Authenticator, Authy, and other 2FA apps. Client-side.
Convert IPv4 addresses to decimal, binary, hexadecimal, octal, and integer formats. Free online IPv4 converter — runs entirely in your browser.
Generate IPv6 Unique Local Address (ULA) prefixes with random or custom 40-bit identifiers. Free, client-side ULA generator.
Look up MAC address vendors using OUI database. Identify device manufacturers from MAC prefixes. Free browser-based tool.
Generate random MAC addresses in bulk. Choose format, separator, case, and locally administered option. Free client-side generator.
Obfuscate text using zero-width characters, homoglyph substitution, or combining marks. Includes deobfuscator. Free browser-based tool.
Free online WCAG contrast checker. Check color contrast ratios for AA and AAA compliance. Test foreground and background colors instantly.
Free online color blindness simulator. Simulate 8 types of color vision deficiency on any color palette. Check accessibility of your designs.
Free online ARIA label validator. Validate ARIA labels, roles, and attributes in your HTML. Ensure screen reader compatibility.
Free online focus order checker. Visualize the tab order of interactive elements on your page. Ensure logical keyboard navigation.
Free online font size checker. Verify if your font sizes meet WCAG 2.1 minimum requirements for readability and accessibility.
Free online alt text generator. Generate descriptive alt text suggestions for images. Improve accessibility and SEO with proper image descriptions.
Free interactive WCAG 2.1 compliance checklist. Track your progress toward AA and AAA accessibility compliance with actionable criteria.
Free online Content Security Policy generator. Build CSP headers to prevent XSS, clickjacking, and code injection attacks. Copy-ready policy.
Free online security.txt generator. Create RFC 9116 compliant security.txt files for responsible vulnerability disclosure. Copy-ready format.
Free online CSRF token generator. Generate cryptographically secure CSRF tokens for form protection. Multiple formats and customization options.
Free online SRI hash generator. Generate Subresource Integrity hashes for scripts and stylesheets. Protect against CDN tampering.
Free online GDPR cookie consent builder. Generate compliant cookie consent banners with customizable styles and categories. Copy-ready code.
Free online privacy policy generator. Create comprehensive privacy policies with GDPR and CCPA compliance. Copy-ready legal documents.
Free online HTTP security headers checker. Audit your website's security headers including CSP, HSTS, X-Frame-Options, and more.
Free online batch text redactor scans and removes emails, phone numbers, credit cards, SSNs, IPs, URLs, and street addresses. All client-side — your data never leaves your browser.
4 articles by Prof. Noah
A step-by-step guide to adding password protection to any PDF file — entirely in your browser, with nothing uploaded to any server.
Not all free tools are truly free — some upload your files to servers where they can be mined, stored, or leaked. Here's how browser-based tools protect your data.
Before you email that spreadsheet, paste that log file, or share that document — run through this checklist to strip hidden metadata, PII, and invisible characters that could expose more than you intend.
Desktop apps have unrestricted access to your file system, network, and hardware. Browser-based tools run in a sandbox and process data locally — making them the safer choice for sensitive work in 2026.