Sergey Leschev | Team Lead | CTO

Swift (L6+) | TypeScript (L6+) | Design Patterns (L6+) | System Architect (L7+)

Google Engineering Level: L7+

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🏆 Awards

Ranking #Dev: Global TOP 200 (Certificate)

<a href="https://leetcode.com/sergeyleschev/"><img itemprop="image" alt="Sergey Leschev" src="https://github.com/sergeyleschev/sergeyleschev/blob/main/leetcode-ranking.png?raw=true" width="410"/></a>

<a href="https://leetcode.com/sergeyleschev/"><img itemprop="image" alt="Sergey Leschev" src="https://github.com/sergeyleschev/sergeyleschev/blob/main/leetcode-medals.png?raw=true" width="280"/></a>

Languages: Swift, TypeScript, Shell, Database (T-SQL, PL/SQL, MySQL).

Algorithms: linked lists, binary search, hash table, queue/stack, dfs/bfs, sort, heap/hash, two pointers, sliding window, tree, greedy problems etc.

🚀 Developer Roadmap

• S.Leschev iOS Developer (Google Engineering Level: L6+) Roadmap.
• S.Leschev FullStack Developer (Google Engineering Level: L6+) Roadmap.
• S.Leschev React Custom Hooks (Google Engineering Level: L6+) Roadmap.
• S.Leschev Responsive Email Design (Google Engineering Level: L6+) Roadmap.
• S.Leschev Design Patterns (Google Engineering Level: L6+) Roadmap.
• S.Leschev System Architect (Google Engineering Level: L7+) Roadmap.

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💻 Technologies

Tech Stack (L7+)

Swift [4, 5+, UIKit, MVP/VIPER/MVVM, Autolayout, UIKitPlus, GCD/Operations/Concurrency 5.5+, Alamofire, ObjectMapper, SwiftLint, SwiftGen, FP, pre/after-main opt], SwiftUI [iOS, watchOS, Widgets, App Clips], Apple TV/AirPlay [Composition, Secondary Display], Realm, Lottie, JWT, CryptoSwift, RxSwift, Vapor [4+] [API;Fluent;Migrations], SwiftNIO [2+], REST, Firebase, Java [7-8], PWA, Angular [2-6+], Ionic Framework [3-5+], React Native [Redux, MobX], JavaScript, React [Next.JS; Redux, Redux Tookit +Slice/Immer, Prime React], CSS [scss], Node.js [10x Express/SQL;14x NestJS 6;7;8+/TypeORM], TypeScript (+ESLint, Jest), C#, .Net Core [1-3+], MS SQL [2016+], SQL, Objective-C, MongoDB [3.6, 4.4, Config, Replication, Sharding], Elasticsearch, RabbitMQ, GraphQL [Schemas; Resolver; Request; Validation; Queries&Mutations; Apollo; Reactive], Apache Kafka, Mockapi, PostgreSQL, Redis, Memcached, Mac Os, iOS [10;12;13;14+], Android (Kotlin), OneSignal, Localization (Phrase/json/i18next), Zeplin, Figma, Sketch.

Analytics (L6+)

Tableau, Amplitude [SDK], AppsFlyer [SDK 5, 6+, Raw Data, Data Locker, Protect360, web-2-app, People-Based Attribution (PBA), Conversion Path, OneLink], Facebook for Business [SDK, Graph, Conversions Api, Pixel, Reports], Snapchat, TikTok, Google Tag Manager (GTM), Google Analytics [GA4;UA], Apple SKAd (+PCM), Qlik, Yandex, Hotjar, SplitMetrics, Apphud, Appfollow, A/B testing, Airflow, Airbyte, Qonversion.

Infra/DevOps (L6+)

Fastlane, CI/CD tools [XCode Cloud, Github Actions/DO, Jenkins, Codemagic, Gitlab, AWS CodeBuild], Git [+Flow], Chromium + Transporter, Instana, Freshworks, Docker [+compose], Kubernetes, Twilio, Zapier, Linux [+ssh, iptables, Ubuntu 16/18/20+, snap/apt/npm/yarn/brew], Amazon Web Services (AWS), Digital Ocean (DO), GRE, IPSEC, VPN, Cloudflare [DNS, CDN, SSL, Guard, Rules], Crashlytics, Grafana, Sentry, RayGun, Nginx, Let's Encrypt [SSL], Win Server [+PowerShell], IIS, Pingdom, UptimeRobot, Apache JMeter, PAW, Postman, Charles Proxy, Indigo Browser, Published Apps [Apple AppStore, Google Play, Amazon Appstore, Huawei AppGallery, Galaxy Store, Snapcraft].

Payment Providers (L6+)

Apple StoreKit [+Retention, Sales Reports], Stripe [nest-SDK, node-SDK, Stripe Checkout, Stripe Elements, Stripe Prebuilt Page, Stripe via iframe, Sigma SQL Financial Reports], PayPal [SDK], high-risk processing providers [Solid Payments, Recurly, SolidGate, Braintree], CloudPayments, DCB (fortumo), Paymentwall, SafeChange, CCBill, Klarna, Pikassa, Paymentwall, Exactly, Realisto, Cypix, Payselection.

DeFi

Web 3.0: Solidity, Javascript, Hardhat, REMIX, Ethers.js, Ganache, TypeScript (react.js, node.js). Solidity (Consensys, Alchemy), Metamask, SafePal, Launchpad, PancakeSwap (BNB), Uniswap (ETH), Dextools/PooCoin, Gas/gwei Optimization, Front-Runner Bots, Slippage Optimization, CEX/DEX, Binance Smart Chain (BNB), Ethereum (ETH), Polygon (Matic), Tokens List [Coinmarketcap;CoinGecko].

Auth Providers (L6+)

Apple ID, Google, Facebook (Meta), Fitbit.

Support Services (L6+)

Intercom, Hiver, ChargeBee, HelpShift, HelpCrunch, Freshchat.

Reports (L6+)

P&L, CF, Key metrics, Unit-economics [AARRR, RARRA], Cohort analysis.

PM Stack (L7+)

Agile [Scrum, Kanban, +V&E +ICE +RICE, PRINCE2], Driven Development [TDD, BDD/QUICK, DDD, FDD], ISTBQ, Clickup, Jira, Confluence, Notion, Asana, Team Foundation (TFS), Miro, diagrams.net/ERD, Microsoft Project, OmniPlan, UML [IBM Rational Rose, Visio], Reetro.

React Custom Hooks (L6+)

useArray useAsync useClickOutside useCookie useCopyToClipboard useDarkMode useDebounce useDebugInformation useDeepCompareEffect useEffectOnce useEventListener useFetch useGeolocation useHover useLongPress useMediaQuery useOnlineStatus useOnScreen usePrevious [useRenderCount](htt