Mask Thai personal data (PII) before sending it to an external AI, then restore the real values locally. Everything runs on your machine — raw PII never leaves the device (PDPA-friendly).

PSU Future Tech Challenge 2026 · AI Innovation for Future Society (Prototype)

• AI Guard — on ChatGPT / Claude, replace PII with tokens ([ชื่อ_1]) or realistic fake data before sending, then restore the real values from the reply.
• True PDF redaction — black out PII in a PDF (removed from the text layer), returns the redacted file + before/after preview.
• PDPA report — risk score plus Section 26 sensitive-data flags (health, religion, …).

Detection runs locally: regex + checksum (Thai ID mod-11, phone, email, …) and Thai NER (PyThaiNLP). No cloud AI is used to detect.

The tool is two parts: a local backend (the engine) and a browser extension (the UI on ChatGPT/Claude). Install the backend one of two ways, then add the extension.

Option A · Windows .exe (recommended, no Python needed)

1. Download AIGuard.exe from the Releases page.
2. Double-click it. Windows SmartScreen may warn about an unknown publisher (the build is unsigned) — click More info → Run anyway.
3. A console window opens and your browser opens to the API docs. The backend is now running at http://localhost:8000.
4. Keep the window open while you use the tool; close it to stop.

The .exe is self-contained — it bundles the Thai NER model and works offline. No Python, no install.

Option B · From source (Windows / Linux / macOS)

Prerequisites: Python 3.11+ and git.

git clone https://github.com/Teerapat-Vatpitak/thai-pii-redaction.git
cd thai-pii-redaction

./run.ps1     # Windows (PowerShell)

./run.sh      # Linux / macOS / git-bash

The script creates a virtual environment and installs dependencies on first run (a few minutes). The first time Thai NER runs it downloads a ~2 MB model (needs internet once).

Verify either option: open http://localhost:8000/api/health → you should see {"status":"ok","version":"2.0.0"}.

1. Open chrome://extensions in Chrome / Edge (any Chromium browser).
2. Turn on Developer mode (top-right).
3. Click Load unpacked and select the extension/ folder from this repo. (With the .exe, clone or download this repo to get the extension/ folder — only the backend needs no Python.)
4. Pin the AI Guard extension so you can reach its popup. It activates on chatgpt.com, chat.openai.com, and claude.ai.

See extension/README.md for details.

1. Type a prompt containing PII into the chat box.
2. Click Mask PII (the floating AI Guard bar) — your text becomes tokens or fake data.
3. Send it with the site's normal Send button.
4. When the AI replies, click Restore PII to see the real values.

• "Backend offline" in the extension — the backend isn't running. Start the .exe or run script (Step 1).
• Port 8000 already in use — close whatever is using it, or stop a previous backend instance.
• SmartScreen blocks the .exe — expected for an unsigned build; choose More info → Run anyway.
• Extension bar doesn't appear — reload the ChatGPT/Claude tab after loading the extension.

Switch in the extension popup.

In examples/ (all PII is fabricated): three realistic Thai prompts and a sample Thai PDF. Explore the API at http://localhost:8000/docs, or:

curl -X POST http://localhost:8000/api/sanitize \
  -H "Content-Type: application/json" \
  -d '{"text":"ผมชื่อสมชาย ใจดี โทร 081-234-5678","mode":"surrogate"}'

Catches free-form Section 26 content keywords miss (e.g. "ป่วยเป็นเบาหวาน") via a MiniLM model:

pip install -r requirements-ml.txt   # large; the feature self-disables if absent

(Not included in the .exe.)

The token↔original vault is in memory only — never written to disk or sent over the network. The extension stores only a session_id. The external AI sees only masked text.

PYTHONUTF8=1 python -m pytest

Architecture and module map: CLAUDE.md. Note: PyMuPDF is AGPL-licensed.

./build_exe.ps1     # -> dist/AIGuard.exe