I built MaskMySheet to stop myself (and you) from accidentally leaking sensitive data in Google Sheets
Hey Indie Hackers,
I'm excited (and a little nervous) to share what I've been working on. It's called MaskMySheet, and it's a Google Sheets™ add-on I built to solve a problem that has given me anxiety for years.
TL;DR: MaskMySheet is a privacy shield for your spreadsheets. It lets you intelligently mask, redact, and anonymize data with a few clicks before you share a sheet with clients, colleagues, or anyone else.
The "Oh Sh*t" Moment
The story starts with that familiar feeling of dread. You've prepared a Google Sheet packed with valuable data, and you're about to share it. But right before you click that blue "Share" button, you panic.
"Did I remove all the customer emails? Are there any salary details still in that hidden column? What about those private notes?"
I've lived this nightmare. I'd spend 15 minutes duplicating my sheet, manually deleting columns, and doing a clumsy find-and-replace, only to still feel a knot in my stomach, convinced I'd missed something.
As a developer, I also faced the constant challenge of creating realistic test data. I wanted to use a sample of production data, but I couldn't do it without a safe, effective way to anonymize it first.
I looked for a tool to solve this properly. I found some that were too simple, and others that were enterprise-level overkill (and price). I couldn't find what I needed, so I decided to build it myself.
The Solution: MaskMySheet
MaskMySheet is a simple add-on that lives in your Google Sheets sidebar. It doesn't try to do a million things. It does one thing well: it protects your data.
You can do the basics, of course:
* Character Masking: Partially hide data, like jo**@ex***.com.
* Redaction: Completely replace data with a placeholder like [REDACTED].
* Data Shuffling: Scrambles the characters in a string to make it unreadable.
* Hashing (SHA-256): This is a powerful one. It converts data into a secure, irreversible, and unique "fingerprint".
Here's why hashing is critical for data analysis: while pseudonymization creates realistic but random replacements, hashing guarantees that the same input (e.g., user_123) will always produce the same unique output (e.g., a94a8fe5...). This means you can safely share a dataset and still perform accurate analysis like counting unique users or joining tables on an anonymized ID. It's the perfect method for preparing data for BI or statistical work where uniqueness matters.
The Real Game-Changer: Pseudonymization
But the feature I'm most proud of, and the one I really built for fellow makers and devs, is Format-Preserving Pseudonymization.
This isn't just hiding data; it's replacing it with realistic, structurally-identical fake data.
Imagine this: you have a column of real user emails. With one click, MaskMySheet can turn them into a list of perfectly valid, but completely fake, emails, while keeping the original domains if you want. Or it can swap real credit card numbers with fake ones that still pass basic format validation.
This has been a lifesaver for me when creating high-quality, safe test datasets. It supports over 30 data types, including names, IPs, phone numbers, crypto addresses, and more.
The Ask & The Feedback
I'm not a big corporation; I'm a solo maker who built this to solve a personal problem. That means your feedback is the most valuable resource I have.
The add-on is live on the Google Workspace Marketplace and is free to install.
Marketplace Link: https://workspace.google.com/marketplace/app/maskmysheet/776056248878
I would be honored if you'd give it a try.
I've set up a Discord server to chat directly with users, get honest feedback, and figure out what to build next. No corporate fluff, just direct conversation.
Discord Link: https://discord.com/invite/UadnhaCnmQ
Let me know what you think in the comments. What's missing? What data types would make your life easier? I'm all ears.
Thanks for reading!
Dominic
