
Ivan Stanojevic
Verified Expert in Engineering
Software Developer
Belgrade, Serbia
Toptal member since January 8, 2016
Ivan is a software engineer with over fifteen years of experience developing front-end architectures and working on SaaS products. He has fulfilled various roles in development teams, including leadership, creating testing frameworks, maintaining build scripts, designing and implementing new front- and back-end features, and architecting systems. Ivan is always eager to learn and enjoys sharing his knowledge with others, making him a valuable team member.
Portfolio
Experience
- JavaScript - 15 years
- Node.js - 14 years
- SaaS - 13 years
- TypeScript - 11 years
- React - 9 years
- Express.js - 5 years
- Next.js - 4 years
- Angular - 3 years
Preferred Environment
Git, Linux, MacOS, PhpStorm, GitHub, AWS IoT, TypeScript, React, NestJS, PostgreSQL
The most amazing...
...acknowledgment I've received from clients is that they always know what's going on with a project since I joined the team. I also made processes more efficient.
Work Experience
Full-stack Developer
Toptal Client
- Integrated Gemini Voice Assistant alongside ElevenLabs to power realistic AI voice simulations for sales call practice and performance coaching.
- Implemented a customizable voice persona creation feature, enabling users to build personalized AI buyer personas for realistic sales call simulations.
- Automated post-call analysis delivering detailed performance breakdowns and actionable coaching to improve sales techniques.
- Enhanced code quality and significantly boosted test coverage while resolving critical bugs to ensure application stability and reliability.
- Strengthened application security by adding comprehensive input validation and sanitization to prevent prompt, SQL, and XSS injections during persona information generation.
Senior Software Engineer (Node.js and React)
The Weather Group - Main
- Integrated Samsung Pay into the existing TV application, modifying sign-up and sign-in processes while ensuring seamless integration between the Samsung and Cleeng platforms upon successful completion.
- Resolved legacy device compatibility issues, including browser API version mismatches and varying engine support on smart TVs, enabling the release of new features on old models without performance degradation.
- Collaborated with key stakeholders and third-party vendors to configure and verify all environments, ensuring full compliance with project requirements and facilitating successful integration.
Front-end Developer
SumerSports, LLC - Main
- Developed a robust player database integrating NFL and NCAA player data, analytics on game history, earnings, status, and performance grades, enabling teams to generate customised reports and tools that improved decision-making.
- Implemented a dynamic evaluations feature with position-specific grading forms, allowing scouts to assess players on past games and abilities.
- Designed role-based UI theming and access controls tailored to different organizations and internal roles, supporting personalized interfaces for 32 NFL teams and a default theme.
Senior Software Engineer
The Weather Group - Main
- Created a core player for white labeled product powered by Shaka, React Native video, and HLS.js.
- Developed an ad manager solution to swap ads and content streams based on different policies.
- Replaced the existing 3rd-party player with a custom solution based on Video.js. Created specific player UI for different use cases, such as different content types (e.g., EPG and VOD), screen sizes, and player modes (ads vs linear playback).
- Integrated OneTrust as a tool for managing privacy and data governance.
Front-end Developer
Ceviant Finance Ltd
- Developed the front end of a customer-facing app that allows corporates to easily manage their cash flow across multiple countries, subsidiaries, banks, and accounts.
- Developed an admin app that company team members would use to manage corporates, manage KYC flow for corporate, execute OTC forex deals, and add banks and providers.
- Acted as a team leader and brought stability and order to the team. Selected and onboarded new team members. Mentored and developed new team members.
- Debugged and conducted analysis on production issues. Led efforts in the quick resolution of clients' issues.
- Managed the release process of multiple front-end projects.
Senior Full-stack Developer
Blacc Spot Media
- Developed a multi-tenant, multi-plugin application based on the TwilioFlex platform. Developed the back end to support additional functionalities.
- Reviewed, assessed, developed, documented, and maintained software features. Interviewed, onboarded, managed, and mentored team members.
- Communicated with vendor/client teams in order to resolve issues, remove obstacles, and derive requirements.
- Managed the deployment/delivery process. Resolved issues and supported other developers during the delivery process.
Senior Full-stack Developer
Opt Health
- Developed the front and back end for the app that tracks different health indicators to determent a person's health score and tracks health over time. Users could schedule a private online checkup over the WebRTC.
- Reviewed, assessed, developed, and maintained software features.
- Set up an automated deployment and delivery process and different environments.
Front-end Lead
Virtual Connections – Blacc Spot Media
- Implemented the initial architecture for both admin and public applications.
- Played the role of a front-end technical leader and architect.
- Implement video-chat components based on the TokBox API.
Front-end Developer | Part Owner
Smart and Applied, d.o.o.
- Managed client's requirements, expectations, communication, and relationships.
- Improved the build and delivery process. Resolve issues with third-party integrations.
- Implemented game features, fixed issues, and reviewed other teammates' work. Mentored and managed team members.
Full-stack Web Developer | System Architect
Tele-ID – Blacc Spot Media
- Designed and implemented the front- and back-end architectures for a HIPAA-compliant platform.
- Implemented API endpoints and tests. Implemented UI components.
- Managed development efforts to deliver products in time-constrained conditions.
Full-stack Developer
Blacc Spot Media, Inc.
- Developed and designed a prototype for WebRTC product and event live streaming.
- Assessed the technology stack according to client requirements and compared potential solutions, focusing on GraphQL versus REST, based on our previous implementations.
- Collaborated with the client's tech team to address knowledge gaps and enhance technical depth. Guided them in identifying deficiencies in their requirements and provided solutions to overcome potential future challenges.
Full-stack Web Developer
WABI – Blacc Spot Media
- Implemented missing functionality and API endpoints. Implemented UI components.
- Fixed bugs and improved the codebase. Estimated, reviewed, and implemented features.
- Set up the deployment process. Helped and supported teammates with tasks and issues.
Front-end Developer
3rd-eyes
- Developed the front-end application for a wealth-management application.
- Developed the initial proof-of-concept and minimum viable product.
- Set up the initial front-end architecture in Angular. Implemented reusable UI components. Implemented charts based on the Highcharts library.
Full-stack Developer | System Architect
Surge Broad Band
- Planned and implemented flexible cross-platform architecture using JavaScript as base technology.
- Implemented a platform analytics sub-system.
- Implemented communication between routers and additional hardware to improve additional router features.
Software Architect and Software Engineer
CodeSynapses
- Created front-end architecture in AngularJS for the social network application.
- Worked on a multi-module, front-end build. Created a testing framework.
- Developed and designed tools. Developed a SaaS minimum viable product.
Software Engineer and Front-end Lead
PSTech
- Designed front-end architecture. Designed and implemented a suite of various components.
- Implemented a front-end delivery infrastructure for the application.
- Implemented and maintained a SaaS product. Created a testing framework with Jasmine.
Software Developer
Youngculture
- Developed and maintained features for an e-banking system.
- Managed builds and build scripts for the development team.
- Integrated the system with various third-party systems.
Experience
GotCourts
https://www.gotcourts.comSaaS Platform for Device Managment
Vellino
3rd-eyes
https://3rd-eyes.com/de/Tele-ID
WABI
VirtualConnection - CFF
SmartSlot
FEATURES
• Integration with 3rd-party casinos and providers.
• Custom deploy and release for different clients.
Gravity CX
https://www.gravitycx.ioWe added robust support for managing users and contacts. I added a custom solution over the Twilio flex routing so clients can easily configure with pinpoint precision what an agent should get as a pending task. There is support for canned responses so that agents can be more productive. Many 3rd-party integrations for SSO providers, CRM solutions, and more.
LocalNow HTML5
I was the senior front-end engineer responsible for maintaining, improving, and developing the existing solution for Tizen, Vizio, and Comcast platforms. All the apps can be obtained via a platform-specific distribution system.
Spider Web
https://localnow.com/React Native TWC
SalesFlowAI
https://app.salesflowai.toptal.tech/loginI joined the final development phase as a full-stack developer and successfully drove the project to production release. I implemented a customizable AI buyer persona creation system, integrated Gemini Voice Assistant with ElevenLabs, added protections against injection attacks, boosted test coverage and code quality, resolved critical bugs, and added missing features.
Education
Bachelor's Degree in Computer Science
University of Belgrade - Belgrade, Serbia
Certifications
API Partner Voice
Vonage
API Partner Video
Vonage
API Partner SMS/Verify
Vonage
API Partner Messaging
Vonage
The Fundamentals of Twilio Voice
Twilio
Twilio Platform Certifications for Partners
Twilio
Twilio The Fundamentals of Messaging at Scale
Twilio
Twilo Flex for Partners
Twilio
Skills
Libraries/APIs
Chai, Highcharts, React, Node.js, MobX, Formik, Yup, REST APIs, Google Maps SDK, jQuery UI, jQuery, WebGL, Web Audio API, Lodash, WebRTC, OpenAI API, Playwright, GSAP, Vue, Google API, Twilio API, Twilio Sync API, Vonage Messages API, Vonage Verify API, Vonage Video API, Vonage Voice API, Vonage SMS API, Stripe, Shaka Player, HLS.js, Video Multiple Ad Playlists (VMAP), Objection.js, Redux-Saga, React Native for Web, Zod
Tools
Git, Grunt, Spine, TokBox, Sequelize, MySQL Workbench, Mocha, PhpStorm, Karma, Figma, Vitest, Animatron, GitHub, AWS Elemental MediaTailor, React Apollo
Languages
SQL, HTML5, CSS3, JavaScript, SCSS, TypeScript, CSS, HTML, GraphQL, Sass, XML, PHP, Java, C++, Pascal, MIPS
Frameworks
Angular, AngularJS, Express.js, Bootstrap, PixiJS, Hapi.js, NestJS, Next.js, Angular Material, Jasmine, React Native, Redux, Material UI, Tailwind CSS, Jest, Cypress, Electron, Ionic, MUI CSS
Paradigms
REST, Agile, Best Practices, Code Refactoring, Refactoring, Testing, Functional Programming, Object-oriented Programming (OOP), Agile Software Development, E2E Testing, Unit Testing, Management, Design Patterns
Platforms
GreenSock Animation Platform (GSAP), Linux, Ubuntu Linux, Vercel, MacOS, Twilio, Amazon Web Services (AWS), Heroku, Software Design Patterns, tvOS, Google Cloud Platform (GCP), AWS IoT
Storage
SQLite, Redis, MongoDB, MySQL, PostgreSQL, Google Cloud, Databases, NoSQL
Industry Expertise
Closed Captioning
Other
SaaS, Sprites, API Integration, RESTful Services, Integration, Front-end, Minimum Viable Product (MVP), Full-stack, Back-end, Web Development, Styled-components, CI/CD Pipelines, Engineering, Software Architecture, Project Consultancy, Front-end Architecture, Architecture, Technical Leadership, Problem Solving, Full-stack Development, Legacy Code, Integration Testing, Cordova, Natural Language Processing (NLP), Internet of Things (IoT), Slots, Remote Team Leadership, Team Leadership, Generative Pre-trained Transformers (GPT), APIs, Leadership, OAuth, Single Sign-on (SSO), Finance, Team Management, Engineering Management, User Experience (UX), User Interface (UI), Scalable Architecture, Artificial Intelligence (AI), Large Language Models (LLMs), OpenAI, AI Integration, Serverless, Twilio Flex, Vonage, Software Design, Software Development, System Design, Expert Systems, Algorithms, Networks, Signal Processing, Electrical Engineering, Very-large-scale Integration (VLSI), 2D Games, Streaming, Video Streaming, Over-the-top Content (OTT), TV, HTTP Live Streaming (HLS), Video on Demand (VOD), Ads, M3U8, HTML5 Video, EPG, OneTrust, Google Play Store, LiveRamp, Samsung, Cleeng, Samsung Pay, Vite, Supabase, ElevenLabs Solutions, Gemini API, ElevenLabs Api, OpenAI GPT-4 API, OpenAi GPT-5 API, AI Voice Agents, Gemini Live API, OpenAI GPT-5 API
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