I Built an Open-Source Privacy Firewall for ChatGPT (Runs 100% Locally)

Every developer I know uses ChatGPT or Claude daily. And every CISO in every company is terrified about it — specifically of getting a compliance violation or customer data breach notification.

Not because AI is bad — but because it's too easy to leak sensitive data without realizing it:

• Customer emails


• API keys


• Logs with tokens


• Stack traces with secrets


• HR info


• Employee names / internal IDs

We’ve all pasted something into ChatGPT and thought:

“Wait… should I really be sending this?”

Hence, I built PrivacyFirewall — an open-source, local-first privacy shield that blocks sensitive data before it is sent to any AI tool.

👉 GitHub:

1. Browser Mode (no setup needed)

Works immediately after loading the Chrome extension.

Detects:

• Email addresses




• Phone numbers




• JWT tokens




• AWS keys




• Private key blocks




• Credit card patterns




• IP addresses




• Hash/API keys

This mode requires:

• ❌ no Python




• ❌ no downloads




• ❌ no models




• ❌ no server

Just load the extension and you get instant protection.

2. Advanced Mode (local LLM)

If you enable the optional backend (a FastAPI server running at 127.0.0.1:8765), PrivacyFirewall uses:

• dslim/bert-base-NER (

  
  
  

  Try pasting any of these into ChatGPT:

  
  
  

  [email protected]

  
  
  

  → You'll see a "Email Detected" modal.

  
  
  

  AKIAIOSFODNN7EXAMPLE `

  
  
  

  → Blocked immediately as AWS Access Key.

  
  
  

  Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

  
  
  

  → Caught as JWT token.

  
  
  

  Meeting notes from Sarah Thompson at HR…

  
  
  

  → In Advanced Mode, the local transformer flags PERSON and warns you.

  
  
  

  This all happens locally inside your browser.

  
  
  

  
  
  
  🚀 Quickstart
  

  
  
  

  
  
  
  1. Install the Chrome Extension (Lite Mode)
  

  
  
  

  git clone https://github.com/privacyshield-ai/privacy-firewall.git

cd privacy-firewall



  
  
  

  Load src/extension as an unpacked extension in Chrome.

  
  
  

  
  
  
  2. (Optional) Run the Local AI Engine
  

  
  
  

  

cd src/engine

python -m venv .venv

source .venv/bin/activate

pip install -r requirements.txt

uvicorn main:app --host 127.0.0.1 --port 8765



  
  
  

  Open ChatGPT → paste something sensitive → get warned.

  
  
  

  📖 Full instructions in the repo.

  
  
  

  
  
  
  🏗️ Tech Stack
  

  
  
  
  
  

  • Chrome Manifest V3

  
  

  • Content scripts + background worker

  
  

  • FastAPI for the local agent

  
  

  • Hugging Face transformers

  
  

  • dslim/bert-base-NER for on-device NER

  
  

  • Regex engine for deterministic detection

  
  
  
  
  

  
  
  
  🧩 Current Focus / Roadmap
  

  
  
  
  
  

  • UI settings panel in the popup

  
  

  • Custom detection rules

  
  

  • Support for Slack/Jira/Notion AI

  
  

  • Firefox support

  
  

  • Quantized models for speed (faster inference, smaller footprint)

  
  

  • Packaging the agent into a small desktop app (Windows/Mac/Linux)

  
  

  • Better redaction instead of blocking

  
  
  
  
  

  If you want to help — PRs and ideas are welcome!

  
  
  

  
  
  
  ❓ Common Questions
  

  
  
  

  Does this slow down my typing?
  
  No! Detection runs asynchronously and doesn't block your workflow.

  
  
  

  Can I whitelist certain patterns?
  
  Not yet, but it's on the roadmap as "Custom detection rules."

  
  
  

  Does it work with Claude/Gemini/other AI tools?
  
  Yes! It monitors past events and text input across websites described in the manifest file.

  
  
  

  
  
  
  🤝 Open to Feedback
  

  
  
  

  I'd especially love feedback from:

  
  
  
  
  

  • Security engineers

  
  

  • AI safety folks

  
  

  • Chrome extension developers

  
  

  • People who accidentally pasted sensitive data into ChatGPT 👀

  
  
  
  
  

  
  
  
  Try It Out 🚀
  

  
  
  

  ⭐ Star the repo: https://github.com/privacyshield-ai/privacy-firewall

  
  
  

  Share your feedback in the issues
  
  Contribute if you've got ideas

  
  
  

  Have you ever accidentally pasted something sensitive into an AI tool?
  
  Let me know in the comments! 👇

  
  
  

  Thanks for reading — hope this helps make AI usage a little safer.

  Vollständiger Original-Bericht

  Ausführliche Details, Code-Beispiele & Hersteller-Stellungnahme auf dev.to.

  ↗ Original-Artikel auf dev.to lesen