Interactive OpenSSL 3.x and 1.1.1 command generator. Generate CSRs with Subject Alternative Names (SAN), create local development self-signed certificates, inspect X.509 certs, test remote TLS handshake connections, verify private key modulus matches, convert between PEM and PKCS#12 (PFX), and download ready-to-run shell scripts.
openssl req -x509 -nodes -days 365 -newkey rsa:2048 \ -keyout localhost.key \ -out localhost.crt \ -subj "/C=US/ST=California/L=San Francisco/O=Development Org/OU=DevOps/CN=localhost" \ -addext "subjectAltName=DNS:localhost,IP:127.0.0.1,IP:::1"
Modern browsers (Chrome 58+) reject certificates without Subject Alternative Names (SAN), even if the Common Name is correct.
OpenSSL Command Generator & TLS Cheatsheet is an air-gapped developer utility designed for maximum precision, client-side speed, and uncompromising privacy. Every operation executes entirely within your browser memory.
All computations run locally inside your browser. No strings, tokens, or files are ever transmitted to any remote servers.
Changes update asynchronously in real time as you type, with zero network lag or server queue delays.
Easily copy outputs, download formatted artifacts, or share local configurations using browser-safe states.
Fully functional without an active internet connection. Work safely on planes, trains, or air-gapped networks.
Quickly test, validate, and iterate on openssl command generator & tls cheatsheet workflows during development without running heavy local scripts.
Safely paste sensitive production telemetry or configuration fragments into an isolated sandbox to diagnose issues rapidly.
Achieve standard-compliant, deterministic results regardless of whether you're working on macOS, Linux, or Windows.
Comply with strict enterprise security guidelines where customer data cannot be pasted into cloud web utilities.
Generate secure cryptographic RSA (2048-4096b) and ECDSA (P-256/384/521) key pairs with PEM, JWK, and live sandbox testing.
Compute SHA-1, SHA-256, SHA-384, SHA-512, and MD5 cryptographic hashes.
Inspect DNS records (A, AAAA, CNAME, MX, TXT, NS, SOA, CAA) with Cloudflare & Google DoH in-browser.