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stephendherrera

PROFILE

Stephendherrera

During four months at Mozilla, Sergio Herrera developed and enhanced analytics features across the mozilla/bigquery-etl and mozilla/looker-spoke-default repositories. He built GA4 UID mapping for Firefox Analytics, expanded site engagement tracking, and introduced SEMrush domain overview analytics, using Python, SQL, and LookML to deliver robust ETL pipelines and dashboard views. Sergio focused on data quality by correcting session logic, fixing country mappings, and validating schema changes, ensuring reliable business insights. His work emphasized scalable data modeling and visualization, enabling richer engagement metrics and marketing analytics. The depth of his contributions established a strong foundation for future reporting and analysis.

Overall Statistics

Feature vs Bugs

75%Features

Repository Contributions

23Total
Bugs
3
Commits
23
Features
9
Lines of code
95,078
Activity Months4

Work History

April 2026

1 Commits

Apr 1, 2026

April 2026 monthly summary for mozilla/looker-spoke-default: Focused on data integrity improvements in Marketing Analytics. Delivered a fix to correct outdated country mappings in the semrush_domain_overview view, improving accuracy of country-level marketing analytics and decision-making. No new features shipped this month; all effort targeted bug repair and validation.

March 2026

2 Commits • 1 Features

Mar 1, 2026

Summary for 2026-03: Delivered SEMrush Domain Overview enhancements in mozilla/looker-spoke-default, introducing new views and explores to enable richer domain-performance analytics. Fixed a LookML typo (avgerage_rank -> average_rank) to ensure accurate metrics and reduce analytics confusion. These changes establish a foundation for future reporting and dashboards, delivering measurable business value through improved data quality and deeper insights. Key technologies demonstrated include LookML modeling, data quality practices, and collaborative Git-based development.

February 2026

10 Commits • 4 Features

Feb 1, 2026

February 2026: Delivered end-to-end site engagement analytics, expanded domain analytics, and stabilized engagement metrics across the data platform. Implemented new GA4 site engagement data products, backfill workflows, and domain overview capabilities, enabling robust business insights and scalable analytics for Firefox product engagement.

November 2025

10 Commits • 4 Features

Nov 1, 2025

Month: 2025-11 recap focusing on delivered features, bug fixes, and cross-system data integrations that drive business impact. Key outcomes include the GA4 UID mapping feature for Firefox Analytics, the Firefox AI Window News newsletter rebrand, and the Monitor Plus users Braze synchronization, alongside the Mozilla WNP dashboard enhancements for richer engagement analytics. The work emphasizes data quality, reliability, and actionable insights for cross-channel activation.

Activity

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Quality Metrics

Correctness96.6%
Maintainability88.6%
Architecture93.0%
Performance88.6%
AI Usage26.0%

Skills & Technologies

Programming Languages

LookMLPythonSQLYAMLlkml

Technical Skills

API integrationBigQueryETL processesGA4LookMLLookerPythonPython scriptingSQLanalyticsbigquerycloud computingdashboard developmentdata analysisdata analytics

Repositories Contributed To

3 repos

Overview of all repositories you've contributed to across your timeline

mozilla/bigquery-etl

Nov 2025 Feb 2026
2 Months active

Languages Used

PythonSQLYAML

Technical Skills

BigQueryPythonPython scriptingSQLbigquerycloud computing

mozilla/looker-spoke-default

Nov 2025 Apr 2026
4 Months active

Languages Used

SQLlkmlLookML

Technical Skills

LookerSQLdashboard developmentdata analysisdata analyticsGA4

mozilla/lookml-generator

Feb 2026 Feb 2026
1 Month active

Languages Used

YAML

Technical Skills

LookMLanalyticsdata modeling