When you land on kaisel.dev, you're looking at the project page for an open-source routing library for Flutter and Dart. The site itself is minimal and functional, which is exactly what you'd expect from a developer tool that's more about the code than the marketing. So is kaisel.dev legit? Yes, but with the usual caveats for any small open-source project.
Technically, the site checks out: it uses a valid SSL certificate, loads quickly via Fastly's CDN, and has DNSSEC enabled. No malware or blacklist flags were found. The main thing missing is any direct contact information or an about page naming the maintainers. That's not a red flag for a project like this — many of the best Flutter packages have similar setups. The real trust signal is the GitHub repository linked on the page. That's where you'll see the source code, issue tracker, and commit history. A quick look at the repo will tell you far more about the project's health than any website ever could.
Since kaisel.dev doesn't ask for personal data or payment, the lack of a privacy policy or terms of service isn't a concern. Your judgment should focus on the library's code quality, documentation, and activity on GitHub. The website itself is just a storefront — the substance lives in the repository. If the code looks solid and well-maintained, you can proceed with confidence.