Free Tools
Small, private, genuinely useful tools. No ads, no sign-up. Everything runs in your browser.
PurposeLab Studio publishes four free web tools: a water intake calculator, a blood pressure category checker, a journaling prompt generator, and a white noise player. All four are free, run entirely in your browser, need no account, and store nothing on a server. There is no paid tier and no trial.
Available tools
💧 Daily Water Intake Calculator
The water intake calculator turns your weight, activity level, and climate into a daily target in litres, using the common 30–35 ml per kilogram estimate. It gives you a starting number and nothing more. It does not account for pregnancy, kidney or heart conditions, or medication that changes fluid balance, and it does not log what you actually drink through the day. If you want the tracking part, that lives in our WaterWise app.
❤️🩹 Blood Pressure Category Checker
The blood pressure checker takes a systolic and a diastolic reading and reports which American Heart Association category those two numbers fall into. That is the whole operation: it compares your numbers against published cut-offs and names the band. It does not interpret the result, does not store or chart readings over time, and is not a diagnosis. For a log you keep yourself, see the BPLog app.
📝 Journaling Prompt Generator
The journaling prompt generator hands you one writing prompt at a time from a fixed set, so a blank page has somewhere to start. Tap again for a different one. It does not save what you write, does not know anything about you, and does not arrange prompts into a course or a thirty-day programme. It is a way in, not a journal. The writing itself belongs somewhere private, which is what Folio is for.
🔊 Free White Noise Player
The white noise player generates white, pink, or brown noise in the browser and includes a sleep timer. Nothing is downloaded and no audio file is streamed; the sound is synthesised as it plays, which is why the page stays small. It does not offer rain loops, curated soundscapes, or a library to browse, and it stops when you close the tab.
What they cost and what they collect
All four are free. There is no paid version, no trial that expires, no advertising, and no account to create. We do not ask for an email address to use any of them.
They also run entirely on your device. Your weight, your blood pressure numbers, and anything you type are handled by JavaScript in the page and are never sent to us or to anyone else. Close the tab and the numbers are gone. The only thing the site records is a page view, through a cookie-less analytics counter that cannot identify you.
These tools are the smallest things we build. If one of them is useful and you want it to remember something between visits, that is usually the point where an app makes more sense than a web page, and our apps follow the same rules: offline first, no account, nothing leaving the device.