Show HN: Check – prefix any command to know if it'll work before you run it

Check is a new command-line tool that lets users prefix any command with 'check' to deterministically verify whether it will run successfully before execution, returning an exit code 0 or 1. The tool costs $0.04 per check with a prepaid balance that never expires, and works with any command that has a network target, including curl, wget, and python.

Prefix any command with check and get one word back. The command is either runnable or it isn't. That's it. Will this command produce a result? Check answers that question. Deterministically, at the speed of an API call, for four cents. Pass any command. curl, wget, httpie, python, node — anything with a network target. From your terminal, a script, a pipeline, stdin, an AI agent — anywhere a command is generated before it's executed. Runnable or invalid. Exit code 0 or 1. No scores, no explanations, no opinions. A fact, not an assessment. Reads from arguments or stdin. Returns an exit code. Works in bash, CI, Docker, cron, webhook chains — anywhere sh runs. Check needs curl and a shell. You already have both. CHECK KEY in your environment for CI and containers.Prepaid balance. No subscription. Never expires. $0.04 deducted per check. Your balance stays until you use it.