Each tool here answers one real question, shows its math in the open, defaults to the conservative assumption, and tells you what it can't know. Everything runs in your browser — no accounts, no tracking, nothing sent to a server.
Can your truck really tow that RV? Fifth-wheel and travel-trailer payload calculators that check the number that actually decides it — your door-sticker payload, not the brochure tow rating. Pass/fail verdicts per limit, the limiting factor named, and a summary you can paste into any forum thread.
SEC financials to a spreadsheet, in one click. A free Chrome extension that pulls any US public company's numbers from SEC EDGAR and exports clean CSV — no API key, no account, nothing leaves your browser. Live on the Chrome Web Store.
Search the full text of every SEC filing since 2001. Real filters, saved searches, match preview, CSV export — free, entirely in your browser. Submitted to the Chrome Web Store, in review.
In progress: cold-climate heat pump sizing (NEEP data) · passport timeline checker · western big-game draw odds. Each ships when it passes review — same rules: free, sourced, honest about its limits.
Whetstone Tools is a small independent shop. Every tool follows the same standard: the methodology is published, the defaults are conservative (we'd rather tell you "cutting it close" than be flattering and wrong), the data source is named, and the page tells you what it can't check. If a tool ever earns money through ads or affiliate links, its privacy page will say so plainly before it happens.