Atrium Browser Lite

Choose the privacy regulations and regions you want to protect against. Atrium masks the matching sensitive data before it ever reaches an AI chat — locally, with zero telemetry.

A Manifest V3 browser extension that intercepts outgoing chat requests on ChatGPT, Claude, Gemini, Microsoft Copilot, Grok, and Perplexity, replaces detected sensitive data (API keys, emails, phones, credit cards, names, and region-specific government & financial identifiers) with reversible placeholders, sends the masked prompt to the LLM, and (optionally) restores the original values when the response streams back.

Open source. No backend. Built in Jakarta — made for everywhere.

Why

Anything you paste into an AI chat can become training data, log data, or third-party data — depending on the provider's policy that week. And depending on where you operate, leaking it can breach a privacy law: GDPR (EU), UU PDP (Indonesia), PDPA (Singapore), the Privacy Act (Australia), or HIPAA / GLBA (US), among others.

Atrium lets you pick the regions and regulations you care about, then catches the matching identifiers — national IDs, tax numbers, health and financial identifiers, names, secrets — in your browser, before they leave. The masking runs locally; this extension has no backend of its own.

Pick your regions

Open the popup and choose the regions you operate in (or a preset: ASEAN, Australia, United States, Global). Only the detectors for active regions run, so you protect against exactly the regimes you need and nothing slows down that you don't.

Region	Maps roughly to	Detects
Global	GDPR, PCI-DSS, secrets hygiene	Email, phone, credit card (Luhn), API keys
Indonesia	UU PDP	NIK, NPWP, names, phone
Singapore	PDPA	NRIC, FIN, passport, UEN, phone
Australia	Privacy Act / APP	Medicare, TFN, ABN, ACN, phone
United States	HIPAA, GLBA, state privacy laws	SSN, EIN, driver license, passport, ABA routing, bank account, health id, phone
Malaysia	PDPA (MY)	MyKad, phone
Thailand	PDPA (TH)	Thai national ID, phone
Vietnam	PDPD	CCCD/CMND, phone
Custom	your policy	any term you add — exact, case-insensitive, or regex

The regulation mapping is a practical guide, not legal advice — Atrium masks identifiers, it does not certify compliance.

What's new in v0.2

• Regions & regulations. Detection is grouped by region with presets and per-region toggles; only active regions' detectors run.
• More platforms. Microsoft Copilot, Grok, and Perplexity, alongside ChatGPT, Claude, and Gemini.
• Activity log. Full searchable/filterable history in IndexedDB with JSON/CSV export (still values-free — type, platform, domain, time only).
• Per-domain controls. Pause/enable masking per site; allowlist or blocklist mode; a "this site" quick toggle in the popup.
• Custom dictionary. Your own always-mask terms — exact, case-insensitive, or regex — with custom placeholder labels.
• Per-detector enable/disable and a char-class fast path for large prompts.
• Cross-browser. Chrome/Edge/Brave + a Firefox build target (see BROWSERS.md).

Install

1. npm install && npm run build
2. Open chrome://extensions → enable Developer mode → Load unpacked → pick the dist/ folder.
3. Open the popup, pick your regions (or a preset), then send a prompt on any supported platform that includes an email, an ID from one of your regions, or an API key. Open the popup — you'll see it counted.

That's it. No account, no signup, no permissions beyond the supported chat domains.

What gets detected

Region	Type	Implementation
Global	Email	Standard pattern
Global	Phone	Local + generic international shapes
Global	Credit card	13–19 digit + Luhn check
Global	API keys	Generic prefixes: sk-, AKIA, AIza, ghp_, xox*-, bearer, JWT
Indonesia	NIK / NPWP / Name	16-digit NIK, dotted/plain NPWP, gazetteer+trigger names
United States	SSN, EIN, driver license, passport, ABA routing, bank account, health id, phone	dashed-only SSN/EIN, ABA checksum, trigger-gated fuzzy ids
Singapore	NRIC, FIN, passport, UEN, phone	NRIC/FIN checksum, distinctive + year-prefixed UEN, trigger-gated passport
Australia	Medicare, TFN, ABN, ACN, phone	all four confirmed by their public checksums
Malaysia	MyKad, phone	dashed shape + DOB sanity; bare form trigger-gated
Thailand	Thai national ID, phone	mod-11 checksum
Vietnam	CCCD, CMND, phone	CCCD province-prefix validated; CMND trigger-gated
Custom	your dictionary entries	exact / case-insensitive / regex with custom labels

Detectors are grouped by region and run only when their region is active (global always runs). This is intentionally a commodity catch — fast and good enough to surprise users with how much it picks up. Atrium for Teams uses the same detection core. What it adds is organizational: team policies, audit logs, compliance reporting, governance workflows, admin controls, and company-wide visibility into AI usage.

Privacy model

• No outbound network calls of its own. The extension does not phone home. Verify in your Network tab — you won't see anything with atrium, monago, or any analytics host.
• Local storage only. Counters, recent activity, and toggle states live in chrome.storage.local and never leave the device.
• In-memory placeholder map. The map from [[PERSON_1]] back to the original value lives in page-session memory only. Cleared on tab unload.
• No values are logged. The recent-activity log stores {type, platform, timestamp} only — never the original values, because logging values would defeat the whole point.

Permissions

Permission	Reason
storage	Local counters and toggle state
host_permissions: chatgpt.com	Content scripts on ChatGPT
host_permissions: claude.ai	Content scripts on Claude
host_permissions: gemini.google.com	Content scripts on Gemini

No <all_urls>. No telemetry hosts. No third-party domains.

How it works (briefly)

Each platform tab loads two coordinated content scripts:

• A MAIN-world script runs in the page's JS context at document_start, monkey-patches window.fetch, XMLHttpRequest, and navigator.sendBeacon before the page's own code captures references to them.
• An ISOLATED-world script handles chrome.* calls — reporting detection events to the service worker for the popup, forwarding toggle state from storage to MAIN.

When a chat-send request goes out, MAIN's per-platform Shaper:

1. Parses the request body (JSON for ChatGPT/Claude, form-encoded for Gemini).
2. Runs the detector on every user-text string.
3. Replaces matches with [[TYPE_N]] placeholders and rewrites the body.
4. Forwards the masked request to the original fetch/XHR.

The response stream is wrapped so the user can optionally see the original values restored in the rendered reply (toggle in popup).

For deeper dives — including per-platform request-body shapes and the hard-won bugs we hit along the way (Gemini's relative URLs in xhr.open, the new Request(input, init) body-disturbance trap, etc.) — see src/main/runtime.ts and src/main/shapers.ts.

Build

Requires Node 18+.

npm install
npm run build           # → dist/ (Chrome / Edge / Brave)
npm run build:firefox   # → dist-firefox/
npm run build:watch     # incremental
npm run package         # → releases/*.zip (both targets)
npm run typecheck
npm run lint
npm run bench           # detector micro-benchmark
npm run audit:privacy   # local-only / zero-outbound guard
npm run format

Edge and Brave load dist/ unchanged. See BROWSERS.md for the WebExtension API audit and the in-browser validation checklist.

Repo layout

atrium-browser-lite/
├── public/                    # static, copied into dist/ verbatim
│   ├── manifest.json
│   ├── icons/                 # 16/32/48/128 PNGs
│   └── popup/
│       ├── popup.html
│       ├── popup.css
│       └── atrium-800x800.jpg
├── src/
│   ├── shared/                # used by all entry points
│   │   ├── types.ts
│   │   ├── detectors.ts       # region-tagged detector registry + engine
│   │   ├── regions.ts         # region taxonomy + presets
│   │   ├── platforms.ts       # supported platform hosts
│   │   ├── labels.ts          # type/platform display labels
│   │   ├── names-gazetteer.ts
│   │   ├── tokenizer.ts       # mask / unmask + placeholder map
│   │   ├── storage.ts         # stats, regions, domain rules, dictionary
│   │   ├── activity-db.ts     # IndexedDB activity history
│   │   ├── bridge.ts          # MAIN ↔ ISOLATED postMessage protocol
│   │   └── messaging.ts
│   ├── main/                  # MAIN-world (page context)
│   │   ├── runtime.ts         # fetch/XHR/beacon patches + tokenizer
│   │   ├── shapers.ts         # per-platform body parsers
│   │   └── (chatgpt|claude|gemini).ts
│   ├── content/               # ISOLATED-world (chrome.* bridge)
│   │   ├── integration.ts
│   │   └── (chatgpt|claude|gemini).ts
│   ├── background/
│   │   └── service-worker.ts  # local storage gatekeeper, no network
│   ├── popup/
│   │   └── popup.ts
│   ├── activity/              # activity-log page
│   ├── settings/             # site settings + detector toggles page
│   └── dictionary/           # custom dictionary page
├── build.mjs                  # esbuild config
├── package.json
└── tsconfig.json

Contributing

PRs welcome. Some directions where help would land well:

• Selector resilience. Platforms ship UI updates; shapers occasionally need adjusting. Open an issue if you see masking stop working.
• More detection types — keep it commodity and locally-runnable.
• Other platforms — Mistral chat, Poe, Perplexity, Le Chat. Each needs a new Shaper in src/main/shapers.ts plus a content script registration in the manifest.
• Translation — popup copy is currently English. Bahasa Indonesia and others welcome.

Before opening a PR: npm run typecheck && npm run build should pass clean. Keep diffs scoped — one feature or one fix per PR.

Roadmap

Shipped in v0.2:

• Activity log page (full history beyond the 30-event ring buffer)
• Per-domain pause (allowlist/blocklist + quick toggle)
• Custom dictionary (local list of strings to always mask)
• Regional detection (ID / US / SG / AU / MY / TH / VN) with presets and per-detector toggles
• More platforms (Copilot, Grok, Perplexity)
• Firefox build target — runtime validation pending (see BROWSERS.md)
• Edge / Brave (Chromium) build — runtime validation pending

What's not in scope

Lite is a single-user tool: one browser, local storage, no central anything. It does not ship team policies, audit trails, compliance reports, SSO, admin controls, or cross-user visibility. Those are organizational concerns, not client-extension concerns.

Lite protects individuals. Atrium for Teams governs organizations.

Built by Monago

Atrium Browser Lite is open source under MIT and built by Monago — an Indonesian AI infrastructure company shipping privacy-first tooling for teams using ChatGPT, Claude, Gemini, and whatever comes next.

Talk to the founder

Maintained by Husein, founder of Monago. Help, feature requests, broken selectors, or AI-privacy chat: 📧 husein@monago.io — replied to personally.

For org-wide deployment (policies, audit logs, on-prem gateway) → Atrium for Teams.

License

MIT — do what you want with this, including forking, modifying, shipping inside other products, and using commercially. Attribution appreciated but not required.