We build the tools you wish existed, then keep them sharp.
Nine brands, built and run by the same small team. Calculators, generators and diagnostics that load fast, work without an account, and show you how they reached the answer.
Different industries, same build
Finance, construction, health, printables, diagnostics, cars, trade paperwork. The subject changes; what goes into building the tool does not.
FinToolSuite
Reliable calculators for saving, investing and planning, built for clarity and speed.
Explore brandFireMathLab
Retirement and financial-independence planning: FIRE dates, withdrawal strategies, Monte Carlo stress tests. Every tool prints the formula behind its answer, and none ask to link a bank account.
Explore brandBuildMetricLab
Field-ready calculators for builders, estimators and engineers. Unit-aware inputs, and outputs a project team can actually share.
Explore brandFitMetricLab
Science-backed tools for training, nutrition and recovery that keep progress honest: macros, training load, readiness, and the numbers underneath them.
Explore brandPrintablesWorld
Printable planners, puzzles and worksheets, plus the PDF and image utilities that get them onto paper.
Explore brandRunTheTests
Hundreds of diagnostic tools that run entirely in your browser: printer test pages, device and connection checks, privacy audits. Nothing to sign up for, install or upload.
Explore brandMotorMath
Jurisdiction-neutral automotive calculators for total cost of ownership, EV vs ICE comparison, and engineering maths. Every tool shows its working, and none of them ask who you are.
Explore brandPlainEstimate
Estimates, invoices and the paperwork around them for small trades. Everything runs in the browser and stays on your machine, and an approved estimate turns into an invoice without anyone retyping it.
Explore brand
Expense Diary
Expense Diary tells you one number every morning: how much you can safely spend today. It works that out from the money in your accounts, the bills still to pay before payday, the money set aside in jars and the days left. Everything stays on your phone: no account, no bank connection, no server.
On Google Play
Plain Estimate: Invoice Maker
Plain Estimate is for one-person trades who quote standing up, in somebody's hallway, with the customer watching. Set your prices once, walk the job tapping them in, hand the phone over for a signature, book the work, do it, invoice it, record the payment. Estimates, invoices, pro formas, credit notes and purchase orders; a hundred and seven document formats; reports for you and spreadsheets for your accountant. Everything is kept on the phone: no account, no server, no monthly fee.
On Google PlayDesign and engineering together
Nothing gets handed over a wall. The person laying out a screen is the person building it, which is why the fast path through a tool and the accessible path through it are the same path.
Checks that run themselves
Automated tests on every change, and latency budgets we actually enforce.
Watch, then change
Usage tells us which tools people come back to and where they give up halfway through. We follow that rather than a roadmap written a year ago, and we are happy to delete a feature nobody opens.
Built for builders.
Sub-120ms response times. Lighthouse accessibility at 100/100. Those are the numbers we hold ourselves to, and they are why a tool that feels quick on a new laptop is still usable on a five-year-old phone.
Have a problem worth solving?
We build internal utilities for teams, and now and again take on a new consumer tool worth making. Tell us what you are stuck with.
Contact us