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1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitchesCheck is a Windows utility for Claude Code that can catch some machine-specific mistakes—such as references to commands, paths, scripts, packages, or Git branches that do not exist on your machine. It is not a general fact-checker or safety layer: a real command can still be the wrong command, and ordinary errors in Claude’s explanations are outside its described checks.
What Check does
GOL Productions describes Check as adding two hooks to Claude Code: one reads information about your machine before each prompt, and another validates each command before it runs. The aim is to give Claude Code evidence about what is actually available on your system, rather than letting it confidently guess a command or path.
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According to the vendor, the checks cover installed programs, scripts and Git references, and package names against npm, PyPI and crates.io. Check also parses shell, Python and PowerShell files for selected syntax problems. JSON and JavaScript files are not currently checked, according to the product pages.
This is a narrow form of verification. It can help when Claude Code invents a tool or dependency, but it does not establish that a command is appropriate for your goal or that an answer in the conversation is factually correct. Anthropic’s general advice remains to verify important claims; it recommends uncertainty, grounding answers in direct quotes and checking claims against citations, while noting that these steps do not eliminate hallucinations: Anthropic’s guidance on reducing hallucinations.
#1 Best Overall
How to install it, and who can use it
GOL Productions says Check is for Claude Code on Windows and requires Node.js 18 or newer. Its product page says npm will not install it on macOS or Linux. The vendor’s installation command is:
npx @golproductions/check@latest --installInstallation adds the hooks to Claude Code’s settings. The command uses @latest, so it requests the newest package version available when you run it; the vendor’s stated platform and Node requirement should be checked against its current instructions if they have changed.
What the free allowance covers
As listed by GOL Productions on its product pages accessed October 4, 2026, Check includes 120 checks per day without signup or a payment card. The vendor lists additional checks at AUD $0.0068 per check, paid from a prepaid balance. These are the vendor’s current stated terms, not a guarantee of permanent pricing.
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- A valid command used for the wrong reason: Check tests whether something exists, not whether it matches your intent. A destructive command can be real and still be a mistake.
- A made-up command that happens to exist: If an invented command coincides with a program installed on your machine, it can pass the existence check.
- Conversation-only errors: The described gate focuses on commands and selected file writes. It is not presented as a checker for inaccurate explanations or reasoning that never becomes an action.
- Some hard-to-inspect command structures: GOL Productions says nested commands or changed working directories can prevent Check from seeing into an action. In those cases, it may let the action through rather than guess.
The vendor explicitly says Check is not a security tool. Treat its checks as a limited source of machine-specific evidence, not permission to run commands without reviewing them.
Rank #3
What Check sends to its server
GOL Productions says command validation runs on its server and that command text and some machine-check results are sent there. The vendor says it redacts some credential patterns, but not all: for example, a PowerShell variable assignment containing a secret may be transmitted as written. These are the company’s disclosures, not an independent privacy audit. Consider that data flow before using Check with sensitive commands or code.
How strong is the evidence for its effectiveness?
The performance figures on GOL Productions’ explanatory page are the company’s own observations, not an independent evaluation. It says it replayed 7,366 real commands from 68 of its Claude Code sessions on one Windows machine. In 11 of those sessions, it found 17 attempts to run a program that was not installed; the company reports that Check blocked all 17. The limited, vendor-run sample does not establish how often Check will catch errors in other users’ environments.
Rank #4
The same page says the prior version blocked 18 valid commands in that replay, and that moving command interpretation to the machine’s own shell removed those false blocks. That is useful context about a failure mode the vendor says it addressed, but it is still a self-reported result from the same limited replay.
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A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11GOL Productions also reports paired sessions using Haiku 4.5, Opus 5.5 and Sonnet 4.5, with 13, 12 and 11 prompts respectively. It says every session without Check fixed a bug by deleting or replacing a user’s file, while none with Check did. Crucially, the vendor says Check’s gate blocked nothing in these runs; the difference came from an earlier standing prompt rule. Those sessions therefore do not measure the gate’s effectiveness at preventing file changes.
The vendor sums up the distinction this way: “The model is not lying. It is not checking. These are not the same problem, but they produce the same result.” That is GOL Productions’ framing, not a guarantee that Check verifies everything Claude Code says or does.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.When Check is a sensible fit
Check may be worth considering if you use Claude Code on Windows and want a hook to flag certain mismatches between its proposed commands or file syntax and your machine. It is a poor substitute for reviewing an action’s effects, validating important claims, or applying security controls. Its stated Windows-only availability, server processing and limited checks are central to deciding whether it fits your workflow.
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