Privacy-first toolbox for builders: LocalTools offers 40+ browser-based utilities — JSON/YAML/XML/TOML formatters, JWT debugger, PEM & PKI tools, HKDF/PBKDF2 playgrounds, AES-GCM, PDF merge/split, image optimizer, Markdown & regex studios, subnets, cron, QR — engineered so sensitive input stays client-side whenever possible instead of disappearing into black-box servers; free with no signup.