JOHLEM

security tools & cheatsheets

37 tools available. No registration required.

🌐

DNS Mapper

Map DNS infrastructure with visual network graphs, subdomain discovery, and ASN lookup

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Phishing Checker

Analyze URLs, domains, and content for phishing indicators and typosquatting

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Email Header Analyzer

Analyze email headers for phishing indicators, spoofing, and security threats

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Hash Generator & Verifier

Generate and verify cryptographic hashes (MD5, SHA-256, SHA-512, and more)

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CIDR Calculator

Calculate IP ranges, subnets, and network addressing for infrastructure planning

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IOC Defanger

Safely defang and refang malicious indicators for secure SOC sharing

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JWT Decoder

Decode and analyze JSON Web Tokens for security issues and debugging

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Password Generator

Generate cryptographically secure passwords and passphrases with entropy analysis

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Base64 Converter

Encode and decode Base64 text and files with URL-safe variant support

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JSON Formatter

Validate, format, and beautify JSON with syntax highlighting and tree view

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IP Info

Analyze IPv4/IPv6 addresses with binary representation and range detection

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Timestamp Converter

Convert Unix timestamps to human-readable dates and vice versa

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Regex Tester

Test regular expressions with highlighting, pattern library, and ReDoS protection

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HTTP Request Builder

Build HTTP requests and export as cURL, fetch, Python, PHP, and more

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Diff Tool

Compare two texts with side-by-side diff and unified format output

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CSV Converter

Parse CSV/TSV data and convert to JSON, SQL, HTML, or Markdown tables

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Character Encoder

Encode text to Hex, Binary, URL, HTML entities, and Unicode escapes

QR Code Generator

Generate QR codes for URLs, WiFi, contacts, and more with custom colors

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Color Converter

Convert colors between HEX, RGB, HSL, CMYK with WCAG contrast checker

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Markdown Preview

Write Markdown with live preview and export as HTML or Markdown file

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Text Statistics

Analyze text for word count, readability scores, and keyword density

Cron Parser

Parse cron expressions, see next run times, and build schedules visually

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Certificate Decoder

Decode SSL/TLS certificates to view subject, issuer, validity, and extensions

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SQL Formatter

Format, beautify, and minify SQL queries with syntax highlighting

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Unix Permissions Calculator

Calculate Unix/Linux file permissions (chmod) with visual editor

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User Agent Parser

Parse browser user agent strings to extract browser, OS, and device information

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UUID Generator

Generate and validate UUIDs (v1, v4) with bulk generation support

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URL Parser

Parse URLs into components, encode/decode, and build URLs from parts

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Bcrypt Generator

Hash passwords with bcrypt and verify existing hashes securely

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MAC Address Lookup

Look up MAC address vendor/manufacturer from OUI database

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Security Headers Checker

Analyze HTTP security headers of any website with scoring and recommendations

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Robots.txt Analyzer

Parse and analyze robots.txt files with URL testing and validation

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CSP Builder

Build Content-Security-Policy headers with visual interface and presets

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String Case Converter

Convert text between camelCase, snake_case, kebab-case, PascalCase, and more

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MIME Type Lookup

Look up MIME types by file extension for correct Content-Type headers

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Subnet Calculator

Calculate subnet information from IP/CIDR with network address, broadcast, and host range

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Favicon Generator

Generate favicons from text, emojis, or solid colors in multiple sizes

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