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Jovan Spasojević
From Serbia 06:12 AM (GMT+02:00)
$40/hr or $60,000/yr

Active 25 minutes ago


Member since Jul 2026

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Senior Full-Stack AI Engineer

AI-native engineer
Available for hire
Years of experience
10+ years
Experience level
Lead
Available for
Full-time, Part-time, Contract, Freelance

Machine Learning Engineer and Backend Developer with more than 10 years of experience delivering AI products from prototype to production. Built and operated end-to-end machine learning systems serving 24 enterprise brands on a platform that processes over 2 trillion events per year, including a Transformer-based model that increased conversion rates by 17%. Combines deep modeling expertise with strong backend engineering across microservices, Apache Kafka, and cloud infrastructure on Google Cloud and AWS. Led a team of 3 engineers, designed experimentation frameworks, and partnered with product and business stakeholders to turn models into measurable revenue.

Languages

Employment History

Staff Machine Learning Engineer at Wunderkind 2024 - 2026
•Increased conversion rates by 17% and migrated 5 enterprise clients off the legacy system by developing a Transformer-based send-time model with a custom ranking loss and hard-example mining for rare conversions; the system now serves approximately 430,000 sends daily. •Delivered models, MLOps pipelines, and runtime services for 24 brands on infrastructure that processes over 2 trillion digital events per year, scaling 5 brands to fully AI-driven delivery. •Established the experimentation and delivery framework (A/B testing, staged rollout, monitoring, and exploration-exploitation strategies) that moved 9 successive timing model generations through full test cycles into production. •Engineered a high-fidelity simulator of production marketing workflows, modeling user clicks, conversions, and unsubscribes from live behavioral data to enable offline evaluation of timing and channel models. •Deployed a budget-constrained channel optimization model that used per-user scoring and dynamic thresholding to steer limited SMS budgets toward cohorts with the highest purchase likelihood and the largest lift of SMS over email. •Architected a campaign prioritization engine, validated it offline with a dedicated simulator, and presented the design to an internal audience of more than 200 people to align engineering, product, and business teams. •Led a team of 3 ML engineers across 4 initiatives (timing, simulation, prioritization, and channel optimization), planning engineering work and partnering with Product, Analytics, and Customer Success. •Operated models on Google Cloud (Kubernetes, Kafka, Deephaven, Iceberg, Trino, and BigQuery) with GitLab and Kargo CI/CD, and created the team's first Deephaven unit-testing framework, since adopted by other engineering teams. •Replaced a legacy Dataflow identity resolution pipeline with a lightweight Python FastStream service, reducing maintenance overhead and adding Grafana monitoring and alerting. •Prototyped internal developer tooling with Claude and other large language models, including agentic coding workflows that automate a pre-commit lint-fixing loop.
Senior Backend Developer at Sentinel Labs Limited 2024 - 2025
•Owned the full technical lifecycle of 2 products from concept to production as the sole technical leader, covering cloud solution architecture, software architecture, product management, development, and DevOps. •Built a PCI card issuing service that deducted cryptocurrency from user wallets during fiat transactions, implemented as NestJS and TypeScript microservices communicating through Apache Kafka. •Launched an API-as-a-service offering for AI agent hosting with a dynamic billing system that charged cryptocurrency per API call through a custom NestJS proxy and a separate transaction processing service. •Administered service discovery, workload orchestration, and secrets management with HashiCorp Consul, Nomad, and Vault, and developed an AWS Lambda provisioner that automatically created and managed client instances. Integrated Web3 and non-Web3 components through secure interface points and maintained rapid, reliable releases with GitHub CI/CD pipelines.
Natural Language Processing Engineer at Novetta Corp 2023 - 2025
•Designed an NLP dialog system in TensorFlow 2.0 that enables non-technical users to create complex, structured queries. •Achieved an F1 score above 95% across 6 natural language understanding tasks on a limited dataset, near state-of-the-art performance, by fine-tuning BERT with multi-task LSTM heads, multiple input streams, and self-attention. •Improved model performance further through data augmentation, custom loss functions, conditional random fields, and hyperparameter search with Keras Tuner. •Coordinated dataset design, collection, cleaning, and annotation with 6 annotators, and released an open-source tool for rapid, hotkey-based multi-label annotation. •Mentored team members on machine learning, TensorFlow, AI architectures, Git, and Docker.

Education

Bachelor of Computer Science at Singidunum University 2011 - 2016