TimeFocuser — The In-Browser Site Firewall That Cannot Be Cheated

Why Regular Site Blockers Fail

Willpower is a finite resource. When digital cravings strike, simple friction is not enough.

❌ Typical Site Blockers

✕
Easy to disable or remove rules mid-session in 2 clicks
✕
Rely purely on client-side JS redirects after pages start loading
✕
Often harvest your browsing history or require cloud logins
✕
Rules can be bypassed simply by disabling the extension
✕
Clunky, dated UI with bloated dependencies

          🛡️ TimeFocuser Firewall
          ✓Strict Anti-Circumvention: Settings are unconditionally locked during active windows
✓Network-Level Firewall: Powered by declarativeNetRequest before packets load
✓100% Serverless & Private: Zero telemetry, zero analytics, zero external servers
✓Cryptographic Integrity: AES-256-GCM + HMAC-SHA256 Web Crypto storage
✓Modern Fast UI: React 18, Tailwind CSS, lightweight and instant

        

Engineered For Deep Work

Built like a real system firewall to protect your attention from modern algorithmic feeds.

🔒

Strict Anti-Bypass Lock

Whenever a scheduled focus window or timer is active, the dashboard enters lockdown mode. You cannot turn off or delete rules mid-session until the session completes.

⚡

Network-Level Interception

Uses Chromium's native Declarative Net Request engine. Restricted sites are stopped at the network transport layer before heavy scripts or media can ever download.

🗓️

Flexible Scheduling

Configure weekly working hours (e.g. Mon–Fri 09:00 to 18:00), launch custom sprint timers (15m, 25m Pomodoro, 60m), or set perpetual 24/7 blocks for toxic sites.

🎯

Granular Match Engine

Block entire domains (e.g., x.com), exact URLs, wildcard patterns (*://*.youtube.com/shorts*), or precise regular expressions.

🛡️

Tamper-Resistant Crypto

Rules and state are protected with AES-256-GCM encryption and signed with HMAC-SHA256 non-extractable keys in IndexedDB via Web Crypto APIs.

👁️‍🗨️

100% Offline & Private

Zero tracking, zero remote analytics, zero cloud databases. Your rules, blocklists, and schedules never leave your local browser sandbox.

How It Works

Get set up in under two minutes.

1

Add Your Distractions

While in Standby (unlocked), open the TimeFocuser dashboard and add the websites you want to restrict using domains or wildcards.

2

Set Your Focus Windows

Choose recurring work hours (e.g. 9:00 AM – 5:00 PM on weekdays) or start an instant countdown focus sprint.

3

Lockdown Engages

The firewall engages. Restricted visits redirect to a calm focus screen. Settings remain locked until your session naturally concludes.

Cryptographic Security Model

How TimeFocuser prevents tampering with local storage files.

🔑

Non-Extractable CryptoKeys

Master cryptographic keys are generated in the browser sandbox with extractable: false, preventing raw export or external script inspection.

📦

AES-256-GCM Encryption

Rule sets and lock states are serialized into encrypted payloads using authenticating AES-GCM ciphers with unique initialization vectors (IV).

✍️

HMAC-SHA256 Signatures

Any out-of-band tampering (such as attempting to alter disk storage files directly) invalidates cryptographic signatures and triggers a fail-closed lockdown.

The In-Browser Site Firewall
That Cannot Be Cheated.