About
One tool, built to be trusted.
Plumline is an independent optimisation tool made by one developer. It exists because the solvers that already work are written for people who studied operations research, and the ones written for everyone else quietly hide how they reached the answer.
Who makes it
Plumline is built and maintained by a single developer, not a company. There is no team, no funding round, and no plan to sell your attention. If something is broken or missing, the person who can fix it is the one reading your email.
Why it works this way
A solver asks you to trust a number you could not work out yourself. Plumline answers that by showing its work: it writes the solution back into your own formulas, lets them recalculate, and shows you the check. You do not have to believe it. You can see it.
On your data
The online solver runs entirely in your browser and uploads nothing. The Google Sheets add-on sends no spreadsheet data to Plumline or third parties; its processing takes place within Google's infrastructure under your own account. There is no Plumline account and no tracking. The full detail is in the privacy policy.
What it solves
Plumline handles linear optimisation with continuous, integer and binary decisions, including mixed-integer models that combine those types. Each decision can carry its own minimum and maximum. Whatever the mix, it writes the answer back into your formulas and shows the limits holding, so the result is one you can check rather than take on trust.