Free developer tools that respect your privacy
DevToolbench is a small, focused collection of free online developer tools — the kind you reach for several times a week but never want to sign up for. There is no account system, no email capture, and no "upgrade to pro" wall on any page. Every tool runs either entirely in your browser or through a minimal serverless proxy, and each one explains in plain language exactly what data leaves your device — and what doesn't.
1. Password & email breach checker
Data breaches have exposed tens of billions of credentials, and attackers replay them in automated credential-stuffing attacks against every major website. Our free password breach checker tells you whether a specific password has appeared in known breach corpora using the HaveIBeenPwned Pwned Passwords database. The privacy design matters here: your password is hashed with SHA-1 locally in your browser, and only the first five characters of that hash are ever transmitted — a technique called k-anonymity. The API returns every breached hash sharing your prefix, and the match happens on your device. The full password never touches the network; you can verify that yourself in your browser's dev tools.
The email breach check answers the other half of the question — check if my email was hacked — by searching known breach databases for your address and listing every service that leaked it, so you know exactly which passwords to change first. We're upfront that this lookup does send your email address over HTTPS to the XposedOrNot API; that's simply how an exact-match email search works, and we'd rather tell you than pretend otherwise.
2. Bulk website speed test
Most free speed tools test one URL at a time, which is painful when you manage a client portfolio, monitor competitors, or regression-test a whole site after a redesign. Our bulk website speed test takes up to ten URLs in a single batch and returns each page's Google PageSpeed performance score alongside the Core Web Vitals that affect search rankings: Largest Contentful Paint, Cumulative Layout Shift, and Total Blocking Time. Each URL also gets a short, prioritized fix list drawn from the Lighthouse audit — the two or three changes with the biggest estimated savings, not a wall of jargon. Audits run against the mobile strategy, matching how Google indexes the web, and a single failing URL never breaks the rest of your batch.
3. Fake data generator
Real user data in a development environment is a compliance risk and a debugging distraction. Our fake data generator produces up to 1,000 rows of realistic mock data across fourteen field types — names, emails, phone numbers, street addresses, companies, job titles, UUIDs, prices, and more — rendered live as you configure it. Export as JSON for APIs, properly escaped CSV for spreadsheets and imports, or ready-to-run SQL INSERT statements with your own table name. It's a free alternative to Mockaroo for everyday volumes: all fields and the full row count are available to everyone, with no account. Generation happens entirely client-side using an open-source library bundled at build time, so there are no rate limits, no outages, and zero network requests after the page loads.
Built to be fast, honest, and free
Every page on devtoolbench.dev ships as static HTML on a CDN, loads without a UI framework, and works on mobile. The privacy policy spells out, tool by tool, what is sent where — because the fastest way to earn trust in security tooling is to be the most transparent site in the results. Bookmark the tools you use, share them with your team, and skip the sign-up sheet forever.