Last Tuesday a developer on our team pasted a config file into Claude. He wanted help debugging a timeout issue. Took him about four seconds. Took us about an hour to realize that config file had three production API keys in it.
He's not careless. He's normal. That's the problem.
Hundreds of millions of people use AI tools every day. They paste code snippets, email threads, spreadsheets, medical records, legal documents. The chat window feels like a private conversation. It's not. Everything you type goes to someone else's servers. Sometimes it becomes training data. Sometimes it gets stored for months or years.
Nobody checks their clipboard before they hit enter. We didn't either. That's why we built BeatMask.
The clipboard is a blind spot
Think about the last five things you pasted into ChatGPT or Claude. Can you remember what was in them? All of it?
Probably not. And that's fine for most of what you share. But mixed in with those paragraphs and code blocks are things you didn't mean to send. A client's Social Security number buried in a spreadsheet row. An API key sitting in a config file. A patient's name in a medical note. A password in a log file you copied too quickly.
You're not being reckless. You're just moving fast. The AI tools are designed to feel frictionless, and they are. That's what makes them dangerous for sensitive data. There's no speed bump between your clipboard and their servers.
What BeatMask does
BeatMask is a browser extension. It sits between you and the AI tools you already use. When you type or paste something into ChatGPT, Claude, Gemini, Copilot, or any other AI chat, BeatMask scans the text before it gets sent.
It looks for the stuff that shouldn't leave your machine. API keys. Passwords. Social Security numbers. Credit card numbers. Names. Addresses. Phone numbers. Medical terminology that suggests patient data. Over 500 detection rules, all running locally in your browser.
When it finds something, it tells you. You can mask the sensitive value with a single click, replacing it with a labeled placeholder. The AI still gets the context it needs to help you. It just doesn't get the actual value.
Here's what that looks like. Say you paste this into ChatGPT:
Dear John Smith, your appointment is confirmed. For verification, your SSN ending in 4589 and your card number 4532-1234-5678-9012 are on file.
BeatMask catches the name, SSN, and credit card number. After masking, the AI sees:
Dear [Name: MASKED], your appointment is confirmed. For verification, your SSN ending in [SSN: MASKED] and your card number [Credit Card: MASKED] are on file.
The AI can still answer your question. It can still help you rewrite the email, fix the formatting, or suggest a better opening. It just never sees the sensitive values. Those stay on your device.
Why local-only matters
There are other tools that claim to protect your AI prompts. Most of them work by sending your data to their own servers for analysis. Think about that for a second.
If the tool that's supposed to protect your sensitive data sends your sensitive data to its own cloud, you haven't solved the problem. You've just added a second company to the list of places your data lives.
BeatMask runs entirely on your device. No cloud servers. No accounts to create. No data ever leaves your browser. We don't collect telemetry. We don't phone home. We can't see your prompts, your detections, or your masked values. Not because we promise not to, but because the architecture makes it impossible.
This wasn't the easy way to build it. Cloud-based detection would have been simpler and probably more accurate for edge cases. But we kept coming back to the same question: would we trust a privacy tool that sends our data somewhere? No. So we didn't build one.
Who this is for
The obvious answer is developers. They paste code all day, and code is full of secrets. Keys, tokens, connection strings, passwords in environment files. BeatMask catches all of it.
But developers aren't the only people pasting sensitive data into AI tools. Not even close.
Lawyers paste contract language with client names and case details. Doctors paste clinical notes with patient information. Accountants paste financial records with Social Security numbers and bank details. HR teams paste employee records with salaries, addresses, and personal information. Salespeople paste customer emails with phone numbers and company data.
Anyone who deals with sensitive information and uses AI tools (which, at this point, is most knowledge workers) is one careless paste away from a data exposure. BeatMask is for all of them.
Free to start, Pro when you need it
BeatMask's free tier covers the basics. It detects the most common types of sensitive data and lets you mask them before sending. No account required. Install the extension and it works.
BeatMask Pro unlocks the full detection engine (all 500+ rules), adds custom rules so you can define your own patterns, and provides session-level analytics so you can see how much sensitive data you're catching over time. It's built for people and teams who handle sensitive information as part of their daily work.
See it in action
We built an interactive demo on the homepage that lets you try BeatMask without installing anything. Paste some text (or use the example) and watch the detection engine work in real time. It takes about ten seconds.
If you like what you see, the extension is available for Chrome and Chromium-based browsers. Install it, and the next time you paste something into an AI tool, BeatMask will be watching your back.
We built BeatMask because we needed it ourselves. We were pasting sensitive data into AI tools without thinking, just like everyone else. The tools didn't exist to stop us, so we made one. We hope it saves you the hour we spent rotating those API keys.