Sergey Leschev Sergey Leschev

Sergey Leschev

Team Lead | CTO

Swift (L6+) | Full Stack (L6+) | Design Patterns (L6+) | System Architect (L7+) | Blog

Google Engineering Level: L7+


πŸ† Awards

Ranking #Dev: Global TOP 200 (Certificate)

Sergey Leschev

Sergey Leschev

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.

πŸš€ Developer Roadmap


πŸ’» Technologies

Tech Stack (L7+)

Swift [4, 5+, UIKit, 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, 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+/TypeORM], TypeScript (+ESLint, Jest), C#, .Net Core [1-3+], MS SQL [2016+], SQL, Objective-C, MongoDB [3.6, 4.4, Config, Replication, Sharding], RabbitMQ, GraphQL [Schemas; Resolver; Request; Validation; Queries&Mutations; Apollo; Reactive], Apache Kafka, Mockapi, Mac Os, iOS [10;12;13;14+], Android, 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+)

CI/CD tools [XCode Cloud, Github Actions/DO, Jenkins, Codemagic, Gitlab, AWS CodeBuild], Git [+Flow], Chromium + Transporter, Instana, Freshworks, Docker [+compose], 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 useScript useStateWithHistory useStateWithValidation useStorage useTimeout useToggle useTranslation useUpdateEffect useWindowSize

Design Patterns (L6+)

Behavioral Creational Structural
🐝 Chain Of Responsibility 🌰 Abstract Factory πŸ”Œ Adapter
πŸ‘« Command πŸ‘· Builder πŸŒ‰ Bridge
🎢 Interpreter 🏭 Factory Method 🌿 Composite
🍫 Iterator πŸ”‚ Monostate 🍧 Decorator
πŸ’ Mediator πŸƒ Prototype 🎁 Facade
πŸ’Ύ Memento πŸ’ Singleton πŸƒ Flyweight
πŸ‘“ Observer β˜” Protection Proxy
πŸ‰ State 🍬 Virtual Proxy
πŸ’‘ Strategy
πŸƒ Visitor
πŸ“ Template Method

Project Guidelines (L6+)

A set of best practices in my projects.


🏫 Education

Belarusian State University

2004 – 2009

Faculty of Applied Mathematics & Informatics.

Computer science / Mathematician-system programmer.


πŸ† Awards

Golden Award for the Year of the Tiger Challenge

Sergey Leschev

Algorithmic skills: Dynamic programming, Greedy algorithms, Catepillar method, Binary search algorithm, Fibonacci numbers, Euclidean algorithm, Sieve of Eratosthenes, Prime and composite numbers, Maximum slice problem, Stack and Queues, Sorting, Time Complexity, Arrays, Prefix Sums, Leader, etc.

Contest: Algorithms, SQL, Data Structures, Bitwise operations (bit-ops), Frontend.


Licenses & certifications


πŸ† Awards

Golden Award Muad’Dib’s Challenge

Sergey Leschev

Algorithmic skills: Dynamic programming, Greedy algorithms, Binary search, Stack and Queues, Sorting, Time Complexity.

Contest: Algorithms, Data Structures.

Languages: Swift.


Contacts

I have a clear focus on time-to-market and don't prioritize technical debt. And I took part in the Pre-Sale/RFX activity as a System Architect, assessment efforts for Mobile (iOS-Swift, Android-Kotlin), Frontend (React-TypeScript) and Backend (NodeJS-.NET-PHP-Kafka-SQL-NoSQL). Moderator of DEV Community. And I also formed the work of Pre-Sale as a CTO from Opportunity to Proposal via knowledge transfer to Successful Delivery.

πŸ›©οΈ #startups #management #cto #swift #typescript #database

πŸ“§ Email: sergey.leschev@gmail.com

πŸ‘‹ LinkedIn: https://linkedin.com/in/sergeyleschev

πŸ‘‹ Twitter: https://twitter.com/sergeyleschev

πŸ‘‹ Github: https://github.com/sergeyleschev

🌎 Website: https://sergeyleschev.github.io

🌎 DEV Community (moderator): https://dev.to/sergeyleschev

🌎 Reddit: https://reddit.com/user/sergeyleschev

🌎 Quora: https://quora.com/sergey-leschev

🌎 Medium: https://medium.com/@sergeyleschev

πŸ–¨οΈ PDF: Download

ALT: SIARHEI LIASHCHOU