Web Apps Development

Engineered 6 SPAs, 3 MPAs, and 3 PWAs in React/Vue with Redux/Vuex, serving 25K monthly users.
Built 35+ REST endpoints in Node.js/Express & Django DRF, using semantic versioning to cut breaking changes by 80%.
Added real-time chat and notifications to 2K devices via Socket.IO, lifting retention by 22%.
Established CI with ESLint/Prettier and Jest/Cypress coverage at 88%, slashing post-release bugs by 60%.
Optimized lazy loading, tree-shaking, and code-splitting for a First Contentful Paint <1.2 s on 95% of page loads.

Iaroslav worked on this case as the Web Developer at Freelance.

Web Developer

PWA Development

Full-Stack Development

SPA Development

Real-time Features

Freelance

Global

Web Applications

Web App

Express

Vue

Django

React

Node.js

Cypress

Jest

B2C

Iaroslav

Full-Stack Web Developer

Iaroslav's cases

Payment Processing System

Payment API Integration and Automation

Integrated a payment API client with a Telegram chat-bot, enabling 500 users to initiate over 300 payments daily.
Developed backend Django ORM logic to automatically generate and persist more than 10,000 payment records annually.
Implemented a cron-based scheduler for payment status updates, achieving synchronization latency under 2 seconds.
Ensured 99.9% accuracy in payment status tracking, reducing payment dispute cases by 40%.

Python DeveloperPeoplePro Tech

Privacy Management Platform

UI Logic Improvement and Onboarding Enhancement

Implemented UI logic to restrict side-panel openings to a single action per click, reducing accidental triggers by 75% across 10+ modules.
Added priority-based log filtering capable of processing over 12,000 entries per minute, cutting average debugging time by 50%.
Enhanced onboarding flow by hiding the 'I already have a server' button for 95% of first-time users, decreasing setup errors by 35%.
Resolved a PC-specific page-update failure affecting 100% of Windows users, restoring full functionality.
Standardized FAB icon dimensions to 48×48 px across 8 Brand Hero pages, achieving 100% visual consistency.

Flutter DeveloperSelfPrivacy

Similar cases

PWA Development

Full-Stack Development

Engineered 6 SPAs, 3 MPAs, and 3 PWAs in React/Vue with Redux/Vuex, serving 25K monthly users.
Built 35+ REST endpoints in Node.js/Express & Django DRF, using semantic versioning to cut breaking changes by 80%.
Added real-time chat and notifications to 2K devices via Socket.IO, lifting retention by 22%.
Established CI with ESLint/Prettier and Jest/Cypress coverage at 88%, slashing post-release bugs by 60%.
Optimized lazy loading, tree-shaking, and code-splitting for a First Contentful Paint <1.2 s on 95% of page loads.

Web DeveloperFreelance

Payment Processing System

Payment API Integration and Automation

Integrated a payment API client with a Telegram chat-bot, enabling 500 users to initiate over 300 payments daily.
Developed backend Django ORM logic to automatically generate and persist more than 10,000 payment records annually.
Implemented a cron-based scheduler for payment status updates, achieving synchronization latency under 2 seconds.
Ensured 99.9% accuracy in payment status tracking, reducing payment dispute cases by 40%.

Python DeveloperPeoplePro Tech

Full-Stack Development

Service Centre Management System

Web App

Built a Global Service Centre Platform

Developed and maintained a web application used by over 80 service centres worldwide.
Contributed to both frontend and backend using React, Next.js, Nest.js, and PostgreSQL.
Ensured cross-device compatibility and high responsiveness across all major browsers.
Integrated scalable API services with authentication and database layers.

Fullstack DeveloperVertikal Ltd

Natural Language Processing

Recommendation Systems

News & Content Platform

Multi-Document Summarization and Ranking Optimisation

Engineered a SOTA multi-document summarization model for news aggregation, achieving an 87% human acceptance rate with less than 1% critical errors.
Designed automated news timelines for evolving events, resulting in a 2.8% increase in content depth and a 1.4% boost in user time spent.
Optimized ranking algorithms with a CTR prediction model, increasing daily active users by 4.3% and user engagement by 2.1%.
Created a novel similarity scoring formula, improving F1-score from 0.91 to 0.95 for news clustering.

ML engineerYandex Zen

DevOps Architecture

Identity & Access Management

Kubernetes

Infrastructure as Code

EdTech

SaaS

Global

Scaling and Securing an EdTech Platform

Replaced legacy VM infrastructure with Kubernetes clusters, reducing infra costs by 30% and improving uptime.
Designed and rolled out a standardised IAM system using self-hosted Keycloak to decouple from third-party providers.
Managed distributed bare-metal NoSQL databases for fast-changing data, cutting storage costs by 50%.
Supported a rapidly growing codebase with 30+ sub-projects through modular cloud-native architecture.

DevOps EngineerAltermeliora