lottie-website-tester
A single .html file JavaScript app that you can throw on your website to test it for 404s, load times, etc. Free. No paywalls. No registration. No install.
Lottie Website Tester is a single HTML file you download and place on your website to check it for problems. There is no account to create, nothing to install, and nothing to pay for. You own the file and can use it however you want.
The way it works is simple: download lottie.html, upload it to any folder on the site you want to test, then open that URL in your browser and click Start crawl. The tool scans every page on your site and reports back what it finds. Because it runs inside your browser, no data is sent to any outside server.
It checks for several types of issues: broken links (pages that return a 404 or error code), slow-loading pages, heavy page weight, insecure resources mixed into secure pages, broken images or stylesheets, and redirect chains. The results appear in a dashboard as the crawl runs, and you can sort and filter the full table of URLs when it finishes. If you need to share results, you can export them as CSV, JSON, a standalone HTML report, or a plain-text summary.
A few things it cannot do: it does not run JavaScript on the pages it visits, so links that only appear after page load will be missed. It also follows your browser's same-origin rules, meaning it can fully check pages on the same domain but gets limited information about cross-domain resources.
The project exists because the author wanted a no-friction way to find broken links on his own sites without creating accounts or dealing with paywalls. It will not gain a paid tier. The tool is simple by design and free to use forever.