Jet Zzz is built by Yaoxi, a solo independent developer. There is no team, no investor, and no growth target — just one person who flew enough long-haul routes to want a better jet lag tool.
A free, browser-based jet lag planner. You enter your flights, set sleep preferences, mark fixed activities, and get a personalized day-by-day plan with sleep, light, and caffeine timing. Calendar and PDF export are built in. Nothing is stored on a server unless you contact me directly.
No account required. No newsletter wall. No tracking beyond anonymous, aggregated analytics. Plain-English content translated into eight other languages, grounded in widely cited circadian-rhythm research.
React + Vite + Tailwind single-page app. The planning engine runs entirely in your browser. Pages are pre-rendered to static HTML so search engines can read them without executing JavaScript.
Feedback, bug reports, and feature ideas are welcome. The contact form in the app sends a message I read personally, usually within a day or two.
My name is Yaoxi. I am an independent developer based between Asia and North America, which is also a polite way of saying I have spent more nights than I would like to admit staring at a hotel ceiling at 3 a.m. wondering why my body refused to cooperate. Jet Zzz is the tool I wish I had on those trips. It is built, maintained, designed, written, and supported by one person. There is no team, no investor pitch deck, and no growth target tied to a quarterly review. The only thing it has to do is be useful to the next traveler who lands jet-lagged and opens a browser.
Independent means I get to make decisions that a venture-backed product would never make. No account wall, because asking for an email before showing value is hostile. No newsletter modal, because nobody wakes up at 5 a.m. in Tokyo wanting to subscribe to anything. No retargeting pixels, because the planner runs in your browser and your trip details are not mine to monetize. The site is supported by a small optional tip jar and — once it qualifies — a handful of contextually relevant ad slots placed inside long-form articles. That is it.
Jet Zzz is a single-page React app built with Vite and Tailwind, prerendered to static HTML so search engines and AI crawlers can read every page without executing JavaScript. The adjustment engine itself is pure TypeScript running in your browser: it reads your flight legs, sleep preferences, prep window, and fixed activities, then produces a day-by-day schedule of sleep windows, light exposure hints, caffeine cut-offs, and optional melatonin timing. Nothing about your trip is sent to a server.
The recommendations are not invented. They lean on widely cited circadian-rhythm research: roughly one hour of phase shift per day under good conditions, the asymmetry between eastward and westward travel, the dominant role of morning bright light in advancing the clock and evening light in delaying it, and the supporting roles of meal timing, exercise, and low-dose melatonin. None of this is novel — what is novel is packaging it into a plan that respects your actual itinerary instead of assuming a clean single-leg flight and an empty calendar on the other side.
The interface and the generated plan are available in English, Simplified Chinese, Traditional Chinese, Japanese, Korean, Spanish, French, German, and Portuguese. Translations are done with a careful human pass on top of machine assistance, because a jet lag plan that reads like a robot wrote it is one nobody will actually follow. The site is keyboard navigable, respects reduced-motion preferences, and degrades gracefully on slow connections.
The contact form is the fastest way. I read every message personally, usually within a day or two, and I genuinely enjoy hearing about edge cases — the four-leg trip with two redeyes, the parent flying with a toddler whose nap schedule refuses to negotiate, the athlete trying to peak the morning after a transpacific. Those reports are what move the product forward.