Calculate Unix file permissions with a visual chmod calculator. Toggle read, write, execute for owner, group, and others. Get numeric and symbolic notation.

Check and validate your Certificate Signing Request (CSR) before sending it to a Certificate Authority.

Validate credit card numbers using Luhn algorithm.

Generate valid test credit card numbers for Visa, Mastercard, Amex, etc. Uses Luhn algorithm. For testing purposes only.

Check if a website is using Brotli compression (br) to speed up loading times.

Design beautiful CSS box shadows visually. Adjust offset, blur, spread, color, and opacity. Multiple shadows, inset support. Copy production CSS code instantly.

Calculate Bloom filter false positive probability, optimal bit array size m, number of hash functions k, memory footprint, and space savings over hash tables.

Interactive 3D Bloch Sphere visualizer and single-qubit quantum state calculator. Calculate state vectors, measurement probabilities, Pauli/Hadamard gates, and density matrices.

Check if an IP address or domain name is listed in popular anti-spam databases and blacklists.

Calculate theoretical operations, real-world CPU execution runtimes, RAM memory consumption, and stack overflow limits for all Big-O algorithmic complexities across input sizes.