Ivan Mijatović

TRADING SYSTEM

Software Architect and Core Engineer · Automated trading system

Polymarket Twin Engine

Deterministic trading infrastructure for prediction markets

Deterministic execution · Backtesting engine · Live trading infrastructure · Event-driven architecture

I design & built a deterministic trading and backtesting platform where live trading and simulations run the exact same strategy and execution logic, ensuring directly comparable and reliable results.

It includes full infrastructure: real-time data ingestion, order book reconstruction, execution engine, order management, portfolio accounting, and research tooling for strategy development.

Impact

First ever backtesting system for Polymarket
Backtest/live 99.6% parity: identical strategy + execution logic on the same tick stream
Processes +200M market events/day through a real-time pipeline (P95 sub-100ms)

My Role

Architected the execution pipeline and deterministic replay model
Built ingestion + storage + replay engine (raw events → storage → reconstruction)
Implemented order management, risk limits, and portfolio/PnL accounting

Engineering highlights

Tick-by-tick replay with full market state reconstruction
Unified execution engine for live trading and backtesting
Parallel backtesting at scale: runs many independent simulations concurrently on shared datasets
High-throughput data egress: streams and persists multi-GB/day market data

Core technologies

TypeScript Node.js Python Parquet Postgres WebSocket Redis React Drizzle Zod Ethers/Viem

Read "Polymarket Twin Engine" case study →

TRAVEL MARKETPLACE

Platform Architect & Lead Backend Engineer

Bookaweb

Multi-vertical travel marketplace operating across 210 countries

Domain-isolated verticals • Deterministic pricing • Conflict-safe reservations • Segmented worker architecture

Bookaweb lets users search and book across 2.4M+ hotels, 300K+ experiences, and flights in 210 countries.

I designed and built the backend infrastructure: multi-provider data ingestion, real-time availability sync, calendar and pricing logic, and end-to-end booking workflows handling live reservations.

Impact

Built a transactional booking system managing availability, pricing, and reservations.
Integrated millions of travel listings from external providers into a unified search experience
Designed calendar synchronization resolving availability conflicts across multiple provider APIs
Implemented scalable search and filtering across large datasets

My role

Designed backend architecture and booking system from scratch
Built booking workflows, calendar logic, and pricing infrastructure
Build partner integration pipelines ingesting and normalizing data from external providers
Owned production infrastructure, database performance, and search indexing

Engineering highlights

Built booking orchestration handling availability checks, pricing, and reservation workflows
Designed real-time calendar sync with conflict resolution across external providers
Built data ingestion pipelines normalizing heterogeneous provider APIs into a unified model
Implemented scalable search and filtering over millions of listings

Core technologies

Laravel PHP Node.js Redis Elasticsearch MySQL Horizon Vue 3 Laravel Nova

Read "Bookaweb" case study →

SAAS PLATFORM

Senior Software Engineer • SaaS platform • 2018–2023

Infinity

Work Management SaaS platform used by 20,000+ companies worldwide

Multi-tenant SaaS • Scalable backend architecture • Real production workloads

Infinity is a work management platform that helps teams organize projects, workflows, and internal operations.

I co-founded Infinity and designed core backend systems, APIs, and infrastructure supporting production workloads globally.

Impact

Used by 20,000+ companies worldwide
Built scalable multi-tenant SaaS platform from scratch
Powered real production workloads globally

My role

Designed backend architecture and APIs
Built core platform systems and infrastructure
Worked across backend, frontend, and system architecture

Engineering highlights

Designed scalable multi-tenant SaaS architecture
Built core backend systems and APIs
Developed real-time and asynchronous workflows
Designed database schema and performance optimizations

Core technologies

PHP Laravel MySQL Vue.js JavaScript REST APIs Docker

Read "Infinity" case study →

Senior Software Engineer and co-founder of Bookaweb & Infinity

Selected Work

Polymarket Twin Engine

Impact

My Role

Bookaweb

Impact

My role

Infinity

Impact

My role

Core Technologies

Languages

Backend & APIs

Queues & Background Jobs

Data & Storage

Infrastructure

Trading Systems

AI & Agent Workflows

Blockchain & Web3

Systems Engineering Focus

Let’s Build Production Systems That Scale