Portrait of Artem Bakalinskii
Artem Bakalinskii, Senior Applied ML Engineer

Artem Bakalinskii

Senior Applied ML Engineer · External Applied ML R&D

External Applied ML R&D for hard data problems

Have a large dataset and a difficult problem your team doesn't yet know how to solve?

I investigate the data, test the critical hypotheses and determine what is worth building before you commit to a full implementation.

  • Billions of events/day Production-scale event processing
  • Up to ~200M users/hour Hourly identity processing cycles
  • Several billion UIDs Behavioral representation space
  • ~1B-row datasets Offline research & training workloads
  • 3–4 years in production Long-running production ML systems

Commercial offer

Research & Feasibility Sprint

  • One difficult data/ML question.
  • Real client data.
  • Focused experiments.
  • Prototype where useful.
  • A clear recommendation on what is worth building next.

Typical scope: one research question · 5–7 business days · representative data · experiments · written findings · next-step recommendation.

Experience

Where this experience came from

Large-scale Applied ML R&D across AdTech and marketplace environments.

AdRiver R&D

Senior ML Engineer — 2021–2024

One of the leading traffic verification and DSP platforms in the Russian market.

Most of my large-scale production ML experience was developed here: identity resolution, behavioral modeling, traffic verification and advertising ML — from poorly defined problems and algorithms designed from scratch to production rollout, automated pipelines and long-term monitoring.

  • Identity Resolution
  • Behavioral Modeling
  • Traffic Verification
  • Targeting
  • DSP / SSP / RTB
  • Large-scale Production ML

Avito

Applied ML / R&D — 2025–2026

Russia's largest classifieds platform.

R&D for the external advertising network — expanding experience beyond a dedicated AdTech platform into a large marketplace environment with its own user, behavioral and advertising data.

  • Marketplace R&D
  • External advertising network
  • Applied ML research
Across both environments, my strongest role has been at the research-heavy end of Applied ML: taking large, messy datasets and unclear technical problems and turning them into tested algorithms and practical systems.

What I do

I work on problems where the answer isn't obvious yet

The most useful work often starts before model selection — understanding whether the data contains the necessary signal, what the actual constraints are, and which technical direction is worth pursuing.

Data Investigation

  • understand what is actually present in the data
  • assess signal quality
  • identify unreliable sources
  • detect hidden constraints
  • challenge initial assumptions

Algorithm & ML Research

  • formulate the problem
  • test hypotheses
  • design algorithms
  • compare approaches
  • evaluate feasibility

Rapid Prototyping

  • build enough of a real solution to test critical assumptions
  • avoid premature production engineering
  • turn research into an actionable technical decision

How I work

From problem to a technical decision

  1. Problem
  2. Data
  3. Research
  4. Hypotheses
  5. Experiments
  6. Prototype
  7. Decision

The goal is not to explore everything. The goal is to collect enough evidence to make the next technical decision.

Selected work

What difficult systems I actually built

First the proof. Details are available if you want the technical depth.

Identity Resolution at massive scale

Up to ~200M users/hour · 3–4 years in production

Built from scratch a production identity resolution system for advertising infrastructure with large volumes of noisy and unstable user identifiers — no reliable global ground truth, shared IPs, bots and cascading false merges.

Fully automated hourly pipeline with persistent graph state, used for traffic verification, retargeting, audiences and downstream ML.

Identity resolution at this scale is a dynamic graph-control problem, not simply pairwise similarity.
Technical details

Technical challenge

  • no reliable global ground truth
  • shared IP addresses
  • high-cardinality and non-unique User-Agent values
  • technical User-Agents, bots, changing identities
  • unreliable external hard identifiers
  • cascading false merges
  • components constantly changing over time

Approach

  • candidate generation
  • deterministic and probabilistic signals
  • filtering of unreliable identity bridges
  • component-level constraints
  • iterative stitch / validate / de-stitch
  • persistent state between iterations
  • fully automated hourly pipeline
  • Grafana monitoring

Pipeline (conceptual)

  • Candidate generation
  • Signals
  • Constraints
  • Stitch
  • Validate
  • De-stitch

Business usage

  • traffic verification
  • retargeting
  • audiences
  • behavioral histories
  • downstream ML

Behavioral embeddings for billions of user IDs

Several billion UIDs · AUC ~0.75 → 0.83–0.85 · ~1.5–2× usable predictions

Built a stable user representation from web and in-app behavior histories (Word2Vec, 100-d embeddings, CatBoost) for gender, age-group, targeting and traffic verification — later reused by other teams.

An exploratory / Kaggle-style experiment helped shape the embedding approach that was then adapted for production at billions of UIDs.

Strong behavioral representation mattered more than adding feature complexity.
Technical details

Architecture

Behavior history → Word2Vec domain/app embeddings (100-d) → user embedding → CatBoost → class-specific thresholds

Research

  • embedding dimensionality research
  • history-window research
  • long-tail filtering
  • label cleaning
  • multiple label-source cross-checking
  • persistent embedding-space design
  • incremental training
  • precision vs coverage optimization

Pipeline (conceptual)

  • Behavior
  • Domain / App Embeddings
  • User Representation
  • Classification
  • Production Predictions

Additional results

  • age model built from scratch
  • up to ~85–88% precision for distinctive age groups
  • embeddings later reused by other teams

Beyond production

Research & Experiments

I use Kaggle competitions and exploratory projects to enter unfamiliar ML domains, test approaches quickly and transfer the strongest ideas into production.

Experiments have included behavioral modeling, 3D medical imaging, MRI and ECG data, segmentation and other applied ML problems.

One Kaggle-style experiment directly influenced the behavioral embedding approach later adapted for a production system on billions of user IDs.

The common pattern is the same: understand an unfamiliar data problem, test hypotheses quickly and find a practical technical direction.

Engagement details

Applied ML Research & Feasibility Sprint

Before committing to a full ML implementation, determine what your data can actually support.

A focused R&D engagement that answers one primary technical question — not a full product build.

  • Is there enough signal in the data?
  • Can X realistically be predicted?
  • Why is the current approach failing?
  • Are these identity signals reliable?
  • Which approach deserves further investment?
  • Should this system be built at all?

What I need

  • a clearly defined problem
  • representative data or controlled environment access
  • basic domain context
  • access to someone who understands the data

What you get

  • data assessment
  • tested hypotheses
  • baseline / prototype where useful
  • technical findings
  • recommended next step

Typical duration

5–7 business days

Sensitive data can remain inside the client's infrastructure. I can work with anonymized samples or within the client's environment.

Flow

  • Problem
  • Data
  • Research
  • Hypotheses
  • Experiments
  • Prototype
  • Decision

Possible outcomes

BUILD

Enough evidence to proceed with development.

INVESTIGATE FURTHER

Signal exists, but more research is needed.

CHANGE APPROACH

Original framing is weak; a better path was found.

STOP

Data or economics do not justify further development.

A well-supported negative result is also a successful R&D outcome.

For suitable problems, I can start with a limited preliminary review of the problem and available data before defining the full research scope.

About

Senior Applied ML Engineer

I'm a Senior Applied ML Engineer focused on research-heavy, data-intensive problems.

My strongest production background is in AdTech, identity resolution and behavioral modeling, but the underlying expertise is broader: investigating large, noisy datasets and finding practical ML approaches where the correct solution is not obvious upfront.

Core

  • Applied ML Research
  • Data Investigation
  • Algorithm Design
  • Identity Resolution
  • Behavioral Modeling
  • Large-scale Offline ML
  • Rapid Prototyping

Domain

  • AdTech
  • DSP / SSP
  • RTB
  • Targeting
  • Traffic Verification
  • Audience Modeling
  • Attribution

Technical

  • Python
  • SQL
  • CatBoost
  • XGBoost
  • Word2Vec / Embeddings
  • ClickHouse
  • Hadoop / HDFS
  • Grafana
  • Docker
  • Linux

Contact

Have a difficult data problem?

If you have data but are not yet sure what can realistically be built from it, send me a short description of the problem.