Pay once
Tools
Time Wheel and The 90% Brain. Each one does a single job. Buy the one you need and keep it.
About
Plain Systems
Software studio, London.
Plain Systems makes small software tools that each do one job, and builds systems to order for businesses and teams. Everything it makes says plainly what it does, and what it doesn't do yet.
Established 2025 by Harry Purcell.
What Plain Systems makes
Three partsTools you can buy, work built to order, and a membership that brings the tools together.
For businesses
Services
A free answer on whether your idea can be built, a £300 systems audit, and custom builds at a fixed price agreed in writing.
Every tool
Membership
Every tool on one account, paid monthly or for 3, 6 or 12 months at a time.
Join the waitlistWaitlist
How the tools are built
Four rulesThese rules decide what gets built and what gets left out.
One job each
If a tool needs a tutorial, it's doing too much.
Built to be fallen off
Miss a week and nothing breaks. You pick it up where you are.
Your data stays yours
Private by default. You can export or delete everything, whenever you like.
Honest about the gaps
Every product page says what the tool doesn't do yet. Nothing is sold as ready before it is.
Where things stand
September 2026What's ready, and what isn't yet.
- Time WheelNewOn sale for £19 once. For Windows 10 and 11, on up to three computers.
- The 90% BrainOn saleThe card pack and tracker, on sale on Gumroad.
- ServicesOpenOpen for enquiries: ideas, audits and custom builds.
- MembershipWaitlistThe waitlist is open. Prices go on the membership page before it opens.
- Time Wheel on Mac and LinuxComingActivityWatch already runs on both. Not built yet. Ask to be told when.
- ConnectorsComingYour calendar first, then other accounts. Not built yet.
- Time Wheel on your phoneExploringOpt-in only, and only if totals can be the only thing that leaves the phone. Ask to be told when.
- Time Wheel for teamsWaitlistYour team sees project totals only, never window titles. Join the waitlist.
Your data
Time Wheel sorts your windows on your own computer. Window titles never leave it: your account only gets project totals, and each computer's name and last sync time. You can export or delete everything whenever you like. The site uses no tracking or advertising cookies. Read the privacy notice.
Get in touch
Questions about a tool, a service or your account go to one address. We read every email.