KutWallet: Multi‑Asset Crypto Wallet with Integrated Exchange (iOS, end‑to‑end)

Designed and built a full‑stack crypto wallet across iOS and backend, covering 26+ screens from onboarding to advanced exchange. ONBOARDING & AUTH: 3‑step value‑driven onboarding carousel with 3D‑rendered illustrations (credit card, leather wallet, vault safe) — each screen communicates a core value proposition ('Most Trusted Crypto Wallet', 'Send Money to Friends', 'Your Safety is our Top Priority') before asking for registration; splash screen with animated KutWallet globe‑infinity logo; email signup with inline validation and social OAuth (Google + Apple ID); login form with password visibility toggle; 4‑digit OTP email verification with custom numeric keypad and 'Resend Code' flow; 4‑digit PIN setup (Sign Up) with circular dot indicators and Face ID icon shortcut; PIN confirmation (Sign In) as the primary re‑entry pattern; Face ID setup screen with clear opt‑in/opt‑out language and Continue CTA; personalized welcome screen ('Hello Jan! Welcome to Kut Wallet') with decorative particle effects. DASHBOARD: user greeting with avatar, total balance displayed on a gradient‑mesh card (purple‑to‑pink with blur, '$ 49,329.77 / Cash available'), Markets section showing crypto assets (BTC, ETH, LTC, XRP) with mini sparkline charts, percentage change (color‑coded green/red), dollar value, and coin quantity; 'See All' navigation to full market list; bottom tab bar with 5 tabs (Dashboard, Wallet, Exchange, History, Account); floating exchange FAB button. EXCHANGE & TRADING: Exchange screen with horizontal pair selector tabs (BTC/USD, ETH/USD, LTC/USD, XRP/USD, EOS/...), asset header (coin icon + name + price + quantity), interactive line/candlestick chart with time‑range selectors (1H, 1D, 1W, 1M, 1Y, 2LL, 2H, 2W), price annotations on chart ($480.60, $489.30), segmented Buy/Sell toggle with orange active state, crypto asset list below chart; Exchange form with Buy/Sell segmented control, amount input in USD ($ 126), crypto selector dropdown (Bitcoin), swap icon for conversion direction, converted amount display ($ 56.01 Litecoin), full‑width 'Exchange' CTA, and native numeric keyboard; Markets list with full asset data (icon, ticker, sparkline, percent change, dollar value, coin amount), 'See All' link.

ACTION SHEET: bottom sheet overlay (Buy / Sell / Convert) with descriptions ('Buy crypto with your local currency', 'Sell crypto to your local currency'), triggered from dashboard FAB. BALANCE & PORTFOLIO: Balance screen with total ($717.00), eye‑toggle for privacy, action tabs (Deposit with down‑arrow, Withdrawal with up‑arrow, Earn with delta icon), per‑asset breakdown identical to Markets format. HISTORY & ANALYTICS: History screen with 'Spending & history' header, donut chart (77% Transactions, Air tickets, Food, Others with color‑coded legend), 'Transactions History' list with 'See All'; full history list grouped by day ('Today') with same asset card format; filter icon in nav bar. SEARCH: dedicated Search screen (nav title + close X) with text input, full asset list rendered below.

QR SCANNER: full‑screen camera viewfinder with red corner brackets, scanning progress line animation, status text ('Scanning...' / 'Cash Added'), and 'Scan Item' CTA button. PROFILE & SETTINGS: Account screen with avatar + name + gender + join date, menu items (View Profile, Push Notification, Pass code lock, Auto Sale, Privacy policy, Data Recovery & Transfer, Language), red‑outlined 'Log Out' button; Profile view (read‑only) with Your name, Email Address, password (masked), Phone Number; Edit Profile with centered large avatar + camera edit badge, editable fields, full‑width 'Save' CTA; Settings screen (Currency USD, Appearance, Color Preference, Clear Cache 1.18 MB, Network test, Certificate Trust Settings, About Us v2.36.2). CURRENCY SETTINGS: Default Currencies screen with Pay/Language tab selector, list of currencies (US Dollar, Australian Dollar, Argentine Peso, Euro, Armenian Dram, Canada Dollar) with country flag icons, search icon, checkmark for selected currency. BACKEND (Node.js + Express + PostgreSQL): WebSocket price aggregation service pulling from CoinGecko REST API + Binance WebSocket as fallback, with 2‑second broadcast interval to connected clients; exchange rate service for fiat conversions (6+ currencies via exchangerate‑api.com); user authentication layer (bcrypt password hashing, JWT access tokens with 15‑min TTL + refresh token rotation, OTP generation with crypto.randomInt and 5‑min expiry); asset portfolio management (per‑user balances, transaction log with ACID guarantees); spending categorization engine (rule‑based classifier for transaction types → category mapping → aggregation for donut chart); QR‑code payload service (generate/validate transfer URIs with amount, recipient, and token type); rate limiting (express‑rate‑limit, 100 req/min per IP for public endpoints, 30 req/min for auth endpoints).