SolveFill: Goal Seek & Linear Solver — Terms of Service
Last updated: 25 October 2026
These terms are between you and Spyridon Pikoulas, who makes SolveFill, an add-on for Google Sheets™. Installing or using SolveFill means you accept them.
The service
SolveFill finds values for cells of your spreadsheet: Goal Seek changes one cell until a formula cell shows the value you ask for, and the solver finds the variable cells’ values that maximize, minimize or reach a value of an objective cell within your constraints, for linear and integer models. Its fields are those of the Goal Seek and Solver dialogs in Microsoft Excel. Check results that matter before you rely on them.
SolveFill writes into the cells you name as the ones to change. While it reads a model it changes them one at a time and puts them back; it then writes the answer there, which you keep or replace with your original values using Restore, as long as the cells still hold the answer. An answer that fails its check in the sheet is not kept: the original values are put back. The optional Answer Report and the sample model are written to new sheets.
Microsoft and Excel are trademarks of Microsoft Corporation. SolveFill is not affiliated with, sponsored or endorsed by Microsoft.
If a solve is interrupted
Before a Goal Seek or solve first changes a cell, SolveFill keeps a copy of the original values in the spreadsheet’s own storage for SolveFill, until you choose Keep or Restore. A solve runs on Google’s servers in steps, and each step puts the cells back before it ends, so closing the sidebar or losing your connection leaves your values as they were, or with the answer written. If the sidebar closed after an answer was written, the next time you open SolveFill in that spreadsheet it offers Keep or Restore.
If Google stops a step before it ends (for example, when it runs past Google’s time limit), the cells can be left holding values SolveFill was trying. The next time you open SolveFill in that spreadsheet, at least six minutes later, it names those cells and offers to restore the copy over whatever they hold then, or to keep them as they are; it starts no new solve until you choose. This cannot always be done automatically: if the copy could not be kept, SolveFill changes nothing, and if the copy was lost or you want values from before later edits, use File > Version history in Sheets to see and restore earlier versions.
Free use and the one-time purchase
Goal Seek is free and unlimited. Each Google account gets 3 solves free in total. One solve is one answer written and checked in the sheet; creating the sample model, Goal Seek, and solves that find no answer or that SolveFill refuses before writing use none. A request with an uncertain outcome keeps its reserved solve unavailable; it is not automatically refunded or repeated. If that happens, write to us and we will restore it.
After that, SolveFill is a $9 one-time unlock per Google account for unlimited solves, paid through Stripe at the price shown before you pay, plus any tax due. There is no subscription or automatic renewal. Models of up to 1,000 variable cells and 10,000 cells read are supported, and Google’s service limits apply to free and paid use.
Any payment can be refunded within 14 days: write to the address below with the Google account email used for the purchase. A full refund or dispute removes the unlock when a later billing check finds it; checks are normally cached for six hours, so this is not instant.
Your part
Use SolveFill lawfully and within Google’s terms. Don’t try to get around the free limit or the purchase check.
Warranty and liability
SolveFill is provided as it is, without warranty of any kind. To the extent the law allows, we are not liable for indirect or consequential loss, and our total liability is limited to what you paid for SolveFill in the 12 months before the claim. Nothing here limits rights you have as a consumer that cannot be limited.
Changes
We may change these terms or SolveFill’s price. A new price applies to future purchases. The date at the top shows the latest version. Danish law governs these terms.