Privacy-First Productivity App: Local-First, Encrypted Sync, Zero Data Selling

Most productivity apps: Your data = their asset. Stored on their servers. Analyzed. Sold. Subpoenable. Used to train AI.

Locked In: Your data = your data. Stays in your browser. Never leaves unless YOU sign in. Encrypted if it does. Zero exceptions.

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The privacy spectrum

App Type	Data Location	Who Accesses	Your Control
Cloud-first (Notion, Todoist, Motion)	Their servers	Employees, partners, law enforcement	Delete account = hope they delete
Hybrid (Obsidian Sync, some planners)	Local + optional cloud	You + cloud provider	More control, but cloud default
Locked In	Your browser (localStorage)	Only you	You own the keys. Cloud = opt-in only.

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What "local-first" means in practice

Default: Zero network calls for YOUR content

Open lockedn.in → Loads from cache → Works 100% offline
Type chaos → AI API call (prompt only) → Plan returns
Save plan → localStorage.setItem('lockedin-v2', ...)
Mood check-in → localStorage
Timer session → localStorage
Streak → localStorage
**Zero bytes of personal content leave your device.**

Optional sync: You decide, you control

1. You click "Sign in" (Google or email) — not before
2. Encryption happens BEFORE leaving device (AES-256-GCM)
3. Pepper key fetched from /api/security/pepper — requires YOUR valid Supabase JWT
4. Supabase RLS — auth.uid()::text = user_id on every table, anon role = ALL GRANTS REVOKED
5. Sign out → local data stays, cloud data untouched
6. Clear all → wipes both instantly

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What the AI sees (minimal, aggregated, never raw)

Each planning request sends:

{
  "mode": "study",
  "effort": "mid",
  "history": [...last 10 messages...],
  "userContext": {
    "streak": 14,
    "totalFocusMinutes": 1240,
    "blockCompletionRate": 87,
    "avgMood": 3.8,
    "avgEnergy": 4.1,
    "moodDirection": "improving",
    "preferredModes": ["study", "chill"],
    "totalPlansMade": 42,
    "alreadyPlannedToday": false
  }
}

Never sent: Raw mood history, exact timestamps, specific plan content, personal identifiers, referral codes, exact streak dates.

Only aggregated stats. The AI knows how you're doing, not what you did.

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Encryption details (for the technical)

Algorithm: AES-256-GCM via Web Crypto API Key derivation: PBKDF2 (100,000 iterations) with:

• User ID (salt)
• JWT-gated pepper (fetched per-session from /api/security/pepper) Format: enc:v1:<ciphertext> Pepper rotation: Per-session, never stored

Result: Even Supabase cannot decrypt your data. Only your browser + your JWT can.

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Supabase RLS: Database-level enforcement

Every table has 4 policies (SELECT/INSERT/UPDATE/DELETE):

auth.uid()::text = user_id

anon role: ALL GRANTS REVOKED — zero anonymous access possible.

PKCE auth flow — no implicit flow token leakage in URLs.

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What we DON'T do (ever)

Practice	Locked In
Sell data to third parties	❌ Never
Train AI on your content	❌ Never (only aggregated stats)
Share with advertisers	❌ Never
Analytics on your content	❌ Never (Vercel Analytics = page views only)
Employee access to your journals	❌ Impossible (client-side encryption)
Government backdoor	❌ Impossible (we can't decrypt)
"Legitimate interest" processing	❌ Never

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Verification you can do yourself

1. Open lockedn.in in incognito
2. "Start free" → "Continue as guest"
3. Type something deeply personal
4. Get plan → complete it → check streak
5. DevTools → Network tab → Filter: "supabase" → Zero requests
6. DevTools → Application → LocalStorage → lockedin-v2 → See your data, encrypted or plain
7. Close tab → reopen → data persists
8. Sign in → Now Supabase requests appear (encrypted payloads only)

Local-first isn't marketing. It's verifiable architecture.

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The "but convenience" counter-argument

"Cloud sync is convenient!"

Locked In gives you both:

1. Guest mode — full features, local-only, zero friction
2. Sign in — encrypted sync, same features, you choose when
3. Sign out → back to guest, local data intact

No "create account to continue" walls. No "premium for sync." You own the data flow.

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Try true privacy (30 seconds)

1. lockedn.in → "Start free" → "Continue as guest"
2. Type your actual chaos (grades, anxiety, burnout, ADHD)
3. Get plan → complete it → mood check-in → streak
4. DevTools → Network → supabase → Empty
5. That's it. Your chaos. Your device. Your choice.

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Locked In: The only productivity app where privacy isn't a feature — it's the architecture. Free, local-first, encrypted-if-synced. Try it here — no account required.