Last updated: 14 October 2026
Gantt Chart for Sheets has no permission to access the internet. Your spreadsheet data is read, turned into a chart, and written back into the same spreadsheet. None of it is transmitted anywhere, because the add-on has no ability to transmit anything.
We do not collect, store, sell, or share your personal information.
It requests exactly two permissions:
| Permission | Scope | What it allows |
|---|---|---|
| See, edit, create and delete only the specific Google Sheets file you use it with | spreadsheets.currentonly |
Read your task list and write the chart into a tab of that same file |
| Display and run third-party web content in prompts and sidebars | script.container.ui |
Show the add-on’s menu and dialog boxes |
It does not request permission to:
The last point is the important one. The add-on does not hold the script.external_request
permission, so it cannot make network requests of any kind. Even if we wanted to send your
data somewhere, the add-on could not do it.
When you install anything from the Google Workspace Marketplace, Google adds
userinfo.email and userinfo.profile to the install screen — your name and your account’s
email address. That is Google’s Marketplace requirement for every listed add-on and it is not
removable by the developer; we tried to take it off the listing and Google puts it back.
The add-on’s own code does not read either of them: its script manifest declares only the two scopes in the table above, and nothing else is available to it at runtime. We do not receive your name or email address from an install, and we do not store them.
Two things are saved using Google’s own storage for add-ons, which lives inside your Google account and is not visible to us:
Both are removed when you uninstall the add-on. You can clear the licence key yourself at any time: Extensions → Gantt Chart for Sheets → Licence → leave the box empty → OK.
Purchases are handled by our payment provider, not by this add-on. When you buy Pro, the payment provider processes your payment details and gives us an order reference and the email address to send your licence key to. We never see your card details. The key is generated and emailed to you automatically by a small script in our own Google account; the order reference and your email address are kept in that script’s private storage, which only we can open.
We keep the order reference and email address only to issue your key, reissue it if you lose it, and meet the record-keeping we are legally required to do. We do not use them for marketing, and we do not share them with anyone.
Your spreadsheet data never leaves Google’s infrastructure. The add-on runs as Google Apps Script, on Google’s servers, beside the spreadsheet it is reading; the chart it produces is written back into the same file. Every connection between your browser and that script is made by Google over TLS.
The add-on does not hold the script.external_request permission, so it has no ability to
open a network connection to anywhere — not to us, not to anyone. This is a property of the
deployed script’s manifest, which Google enforces at runtime. It is not a promise about our
intentions; it is a permission we do not have.
We keep no copy of your spreadsheet data. There is no server of ours for it to be copied to, no database, and no log file that records spreadsheet contents. Task names, dates, owners and everything else are read into memory while a chart is being built and are gone when it finishes.
The only two values that are stored — your display preferences and your licence key, if you
have one — are held in Google’s own PropertiesService, which lives inside your Google
account and is encrypted at rest by Google. We cannot read them.
No person at Slowgrain can access your spreadsheet data, because there is no system through which to access it. There are no employees, no contractors and no third-party processors with a route to it. The Apps Script project that carries the add-on’s code is owned by a single Google account, and publishing a new version of the add-on requires signing in to it.
The secret used to sign licence keys is never committed to our source repository and is not present in any copy of the code we publish. It exists only in the deployed script and in an offline backup encrypted with AES-256.
The chart is written into a tab of your own spreadsheet, so it inherits that file’s sharing settings. Anyone you have shared the spreadsheet with can see the chart, exactly as they can see the task list it was built from. Nothing about the chart is published or shared by us.
Gantt Chart for Sheets does not use any Google Workspace API data to develop, improve, or train generalised or non-personalised AI or machine-learning models. It does not use AI or machine learning at all — scheduling is ordinary arithmetic.
The use and transfer of information received from Google APIs adheres to the Google API Services User Data Policy, including the Limited Use requirements.
This add-on is a business tool and is not directed at children under 13.
If this policy changes, the “last updated” date above changes with it, and the current version is always published at this URL.
Questions about privacy, or a request to delete anything we hold:
slowgrain.dev@gmail.com
We reply within five working days.