Free Tools & Calculators

Every tool on this page started as something we wrote for ourselves — usually because we got tired of pasting webhook payloads into our IDE, or because a client asked us to walk them through an OWASP checklist for the third time. At some point we noticed the same patterns recurring across engagements, and it seemed lazy to keep them on our laptops.

The Stripe webhook tester exists because every single Stripe integration we've audited has had at least one webhook signature failure mode — and tracking down whether the issue is bodyParser, clock drift, or rotated secrets takes longer than the tool itself does. The step-by-step output is the checklist we'd walk through manually.

The OWASP ASVS checklist is what we send to clients before a penetration test. They walk it, mark their gaps, send us the printed PDF — and we end up doing a deeper test on the actually-interesting parts of their stack instead of finding the same OWASP Top 10 issues a junior consultant would catch with Burp.

The JSON-LD generator is what we use when bootstrapping a new client site to make sure the home page Organization markup is right before we worry about anything else. The five types we support — Organization, LocalBusiness, FAQPage, Article, Product — cover 95% of what 95% of sites need.

The cron builder and UUID generator are the "every-day" utilities — the ones you pull up when you need them and forget about until next time. We added them because the existing free alternatives shipped with surprise ads, tracking pixels, or — worse — sent data to a server. None of ours do.

The four cost calculators in the second section are different in nature. They're estimation tools that compress our pricing knowledge — across hundreds of QuantLab engagements — into something a founder or CTO can use to set expectations with their board in 60 seconds. They're not contracts, but they are defensible ranges. If you're scoping a Stripe build, a custom CRM, a security audit, or a build-versus-buy decision, the calculators are a much faster starting point than an open RFP.

Found a bug? Want a tool we haven't built yet? Email us at beltz@quantlabusa.dev. The fastest way to influence what shows up here is to ask. We treat tool requests from our existing clients and prospects with the same seriousness as any product feature.

If you're here because you're evaluating us as a vendor: these tools are a representative sample of how we approach problems. Step-by-step, no magic, no fake AI, no asking for an email before we give you the answer. The full engagement just has a few more zeros and a lot more code. Browse what we do or book a 20-minute call.