Developer Tools
Browser-based utilities for web security and development. All calculations happen locally—no data is sent to any server.
Certificate Inspector
Decode PEM SSL/TLS certificates or fetch from a URL client-side. Inspect subject, issuer, validity, SANs, key usage, and security assessment.
CSP Policy Builder
Build Content Security Policy headers interactively. Toggle directives, see real-time policy generation, and get security ratings for your CSP.
CSP Hash Calculator
Generate SHA-256 hashes for inline scripts. Get ready-to-use CSP directives for your Content Security Policy.
HTTP Security Headers Analyzer
Analyze HTTP response headers for security best practices. Get a security score, recommendations, and detailed analysis for each header.
Password Generator
Generate strong passwords and passphrases using the Web Crypto API. Estimate entropy, crack time, and customize character sets — all client-side.
Base64 Encoder / Decoder
Encode and decode Base64, Base64URL, URL encoding, hex, and HTML entities. File support for images and documents. Runs client-side.
Color Contrast Checker
Check color contrast ratios for WCAG 2.2 AA and AAA compliance with APCA support, color blindness simulation, and auto-fix suggestions.
Cron Expression Builder
Visual cron expression builder with interactive field selectors, common presets, next execution preview, crontab line output, and shareable links.
Regex Tester
Test regular expressions with real-time match highlighting, capture groups, replace mode, and common pattern presets. Runs in your browser.
Timestamp Converter
Convert Unix timestamps to human-readable dates and vice versa. Supports seconds, milliseconds, ISO 8601, RFC 2822, and timezone comparison.
Nginx Config Generator
Generate Nginx server blocks with upstream, QUIC/HTTP3, rate limiting, tarpit, OCSP stapling, Brotli, and modern TLS best practices.
IP / Subnet Calculator
IPv4 and IPv6 subnet calculator with CIDR notation, VLSM planner, range-to-CIDR converter, reverse DNS, and bit boundary visualization.
About These Tools
All calculations happen in your browser. Your code never leaves your device.
No server round-trips. Results update as you type with zero latency.
View the source code on . Contributions welcome. GitHub.