Senior Data Engineer (Full Stack - Data + API) | AdTech Measurement

Type: Contract - 1099 | 6 Months + Extendable Work Schedule: 40 Hours / Week Location: Remote - US Based Only Work Authorization: Must be authorized to work in the US legally | US Citizen / Green Card Only Salary will be discussed on call once we have your details. About The Role We are hiring for a Senior Data Engineer for an end-client in the Ad-Media Measurement space . This is for the Ad Optimization team - the revenue-facing edge of the data platform that turns attributed conversions and impressions into optimization feeds that external partners use to make their advertising models smarter. This is a Contractor (1099) role and includes availability for occasional off-hours release / incident support. Formal on-call is not required unless separately established. Responsibilities Build, optimize, and operate production Apache Spark pipelines that generate attributed conversion and optimization feeds from large-scale impression and conversion data Design and evolve data processing and models across modern data lake and warehouse technologies, orchestrated with a production workflow scheduler on AWS Build and operate partner optimization feeds and integrations with external partners, including schemas, identity fields and unique IDs, file delivery, reconciliation, and SLAs Build, change, and operate production REST APIs , including PHP APIs, delivering secure, backward-compatible changes end-to-end: implementation, validation, authorization, data access, documentation, automated testing, and production diagnostics Trace and modify behavior across controllers, database queries, templates, JavaScript, and automated tests Diagnose production failures, reconcile partner-facing data, execute backfills, and manage staged releases and rollbacks Write and maintain unit and integration tests across pipelines, APIs, and feeds Required Qualifications - Must Haves This is a strict filter. Please do not submit without this. 7+ years of professional experience in software or data engineering 4+ years building, optimizing, and maintaining production Apache Spark pipelines, with strong Java (JVM Spark) AND Python (PySpark) skills Advanced SQL, relational data modeling, and large-scale data processing; production experience with Snowflake, MySQL, and Iceberg 3+ years operating AWS data workloads using S3 and Airflow (or equivalent production orchestration); container orchestration and data-catalog experience a plus 3+ years building, changing, and operating production REST APIs Production full-stack experience with PHP, Symfony (or comparable PHP MVC), Doctrine, Twig, and JavaScript Demonstrated AI-assisted development - Must be comfortable using AI tools for code generation, code review, documentation, investigation, working with agentic code harnesses, and spec-driven development, with judgment on when NOT to trust AI output. This is an AI-forward engineering org. Ability to independently deliver secure, backward-compatible API changes Experience with external provider / client integrations involving schemas, APIs, file delivery, identity fields, reconciliation, and SLAs Preferred / Nice to Have Direct experience building partner optimization or advertising feeds with external platforms (DSPs, publishers, measurement partners) Experience in AdTech / Advertising measurement - attribution, conversions, audience/impression data, identity matching Experience with deterministic and probabilistic identity matching, unique IDs, device IDs, identity graphs Familiarity with edge/log delivery infrastructure and pixel/impression tracking Experience with privacy and compliance-driven workflows (deletion, opt-out, suppression, retention) Experience with data lake table formats and query engines at large scale Interview Process Three rounds. Coding interview is possible. Screening Checklist for Submittal: 7+ yrs SWE/Data Eng? 4+ yrs Java (JVM Spark) + Python (PySpark) prod? 3+ yrs S3 + Airflow/orchestration? 3+ yrs building/operating prod REST APIs? AI-assisted dev tools in professional capacity? Prod experience with Snowflake, MySQL, Iceberg? PHP/Symfony, Doctrine, Twig, JS prod experience? US Citizen / Green Card? Open to 1099, 40hrs/week, 6-month contract? Notice period / How soon can join?