Setup Guide
Learn how to connect your Google account to ThunderSweep
⚠️ Why Google says "This app isn't verified"
🚨 Urgent: Google Verification Deadline
ThunderSweep is a 100% local, privacy-first tool built by a solo developer. Because this app runs entirely locally and requires no external servers, I originally built it to be as cheap and accessible as possible.
However, Google recently changed their rules, stating: "To help keep user data safe, every app that requests access to restricted scope is now required to go through a security assessment validated by a CASA authorized lab. This includes local client applications..."
Because ThunderSweep requires Gmail access to function, there is no way around this. We do not use these permissions to send your data to any external servers—the permissions simply allow the local extension installed completely on your computer to protect your privacy. (Please see the "Why Each Permission Is Required" section below for full transparency).
To satisfy this new rule, Google now forces independent developers to pay corporate security labs thousands of dollars every year for "mandatory audits" just to keep our apps alive on the Chrome Web Store.
Want to dive deeper into why this warning exists and how we are fighting back? Read our full transparency report on the ThunderSweep blog.
If you believe in local, zero-knowledge privacy tools, please consider customizing your setup and upgrading to a paid plan. Every subscription goes directly toward funding this mandatory audit so we can keep ThunderSweep alive for everyone.
How to proceed past the warning today:
- Click "Advanced" (bottom-left of the Google warning screen)
- Click "Go to ThunderSweep (unsafe)" — This is safe. The "unsafe" label simply means we haven't paid the third-party security lab yet. All processing happens 100% locally on your computer.
- Continue to the permissions screen and check all the boxes.
⚠️ CRITICAL: Check All Permission Boxes
When connecting your Google account to ThunderSweep, you MUST check all permission boxes
for the extension to work properly. Missing any permission will cause scanning or vault features to fail.
Required Permissions
ThunderSweep requires the following permissions across Gmail and Google Drive:
View your email messages and settings
Read, compose, and send emails from your Gmail account
See, edit, create, and delete all of your Google Drive files
Why Each Permission Is Required
Crucial context: ThunderSweep is an extension installed locally on your Chrome browser; it is not a remote server or a person. When you grant these permissions, you are giving your local browser the ability to run these security tasks on your own computer. No data is ever sent externally. I have no backend servers.
1️⃣ View your email messages and settings
What it does: Allows the local extension on your machine to map your inbox structure.
Why it's needed: Your browser uses this to identify which emails contain attachments so it knows what to scan.
What it DOES NOT do: It does not give me (the developer) or anyone else the ability to read your emails from a remote server.
2️⃣ Read, compose, and send emails from your Gmail account
What it does: Grants your local browser the ability to download attachments into its temporary memory for scanning.
Why it's needed: Without this, the extension cannot actually inspect PDFs or documents for sensitive information before vaulting them.
What it DOES NOT do: It does not send emails on your behalf, nor does it upload your attachments to any cloud servers for processing.
3️⃣ See, edit, create, and delete all of your Google Drive files
What it does: Gives the extension necessary read/write authorization within your private Drive architecture.
Why it's needed: Your browser must be able to scan your existing Drive files, generate its own encrypted versions locally, place those secure files into your new ThunderSweep Vault folder, and delete the exposed originals.
What it DOES NOT do: It does not give me or my company any visibility into your files. ThunderSweep operates completely blindly on our end.
Privacy & Security
🔒
100% Local Processing
All scanning happens in your browser
🚫
Zero Cloud Upload
Your data never leaves your computer
🛡️
No Data Collection
We don't store or transmit your emails
✅
Verifiable
Check your browser's network tab
Installation Steps
- Install ThunderSweep from the Chrome Web Store
- Click "Connect Gmail Account" in the extension popup
- Select your Google account when prompted
- If you see "Google hasn't verified this app" — click "Advanced",
then click "Go to ThunderSweep (unsafe)" to continue. This is safe. Verification is
in progress.
- CHECK ALL BOXES ✅ ✅ ✅ ✅ on the permissions screen — all four are required
- Click "Continue" to authorize the extension
- Start scanning! 🎉 Your 7-day free trial begins on first scan
Common Issues
❌ "Permission denied" error
Solution: Make sure ALL boxes are checked when connecting your account. Go back and
re-authorize with all permissions enabled — both Gmail and Google Drive.
❌ Scan fails or shows "0 attachments"
Solution: Disconnect and reconnect your account in the extension settings, ensuring all
permissions are granted during the OAuth flow.
❌ Vault won't create or files won't save
Solution: The Encrypted Vault requires the Google Drive permissions. Disconnect and
reconnect your account, making sure the Drive permission boxes are checked.
❌ Extension asks for permissions again
Solution: This is normal after extension updates. Re-grant all permissions to continue
using ThunderSweep. Your previous scan results, vault files, and settings are preserved.
⚠️ "Google hasn't verified this app" warning
Solution: Click "Advanced" → "Go to ThunderSweep (unsafe)". This screen appears because Google's manual verification of our app is still in progress (typically takes a few weeks after submission). It is safe to proceed — ThunderSweep is published on the Chrome Web Store and processes everything locally on your device.