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Daniel Berry

PROFILE

Daniel Berry

Over the past year, D. Berry engineered robust experimentation and telemetry solutions in the mozilla/metric-hub and mozilla/experimenter-docs repositories. Berry designed and implemented TOML-based experiment configurations, SQL-driven analytics pipelines, and Glean telemetry integrations to support data-driven product decisions across Firefox platforms. Leveraging Python, SQL, and TypeScript, Berry enabled granular metrics tracking, cross-device onboarding experiments, and region-specific feature rollouts. Their work included authoring technical documentation on statistical methods and experiment sizing, improving onboarding for new contributors. Berry’s contributions emphasized maintainable configuration management, precise data collection, and clear documentation, resulting in scalable experimentation infrastructure and enhanced analytics capabilities for Mozilla’s product teams.

Overall Statistics

Feature vs Bugs

97%Features

Repository Contributions

34Total
Bugs
1
Commits
34
Features
28
Lines of code
4,026
Activity Months12

Work History

April 2026

1 Commits • 1 Features

Apr 1, 2026

April 2026: Delivered VPN Experiment Enrollment Configuration for mozilla/metric-hub, introducing a dedicated TOML-based configuration to control the enrollment period for VPN experiments. This enables staged feature testing, safer rollouts, and faster validation of VPN-related changes. The change centered on a single commit: 9372a31549e886ad542f3e6bf7611b3c16d24595 with the message 'Create vpn-mvp-beta-holdback.toml (#1393)'. No major bugs fixed this month; work focused on enabling configurable experiment enrollment and improving testing capabilities, contributing to reduced risk and clearer rollout criteria.

January 2026

1 Commits • 1 Features

Jan 1, 2026

January 2026: Focused on delivering the Experiment Population Sizing Guide for the mozilla/experimenter-docs repository. Produced a comprehensive documentation resource covering statistical power, exposure rates, and design patterns to optimize experiment outcomes. Delivered the first draft and updated sizing.md, establishing a foundation for standardized experimentation practices and improved decision-making across teams.

November 2025

1 Commits • 1 Features

Nov 1, 2025

November 2025 (Month: 2025-11) - Focused on improving the Firefox VPN integration's configuration management in the metric-hub repo. Delivered a Windows 10 configuration file rename to enhance clarity and user experience. Implemented a targeted fix for issue #1247 related to Windows 10 VPN configuration handling (commit b424c4852fb42bfd90df170ad6c6db7f6294d150). This work reduces onboarding friction for users and helps support teams diagnose configuration issues faster. Maintained strong code quality with precise commit messages and alignment to issue tracking.

August 2025

4 Commits • 3 Features

Aug 1, 2025

In August 2025, mozilla/metric-hub delivered targeted analytics improvements and multi-region experiment instrumentation, strengthening data-driven decision making around tab groups and sign-in UX. The work expanded measurement scope, enabled richer segmentation, and extended data collection windows to support robust analysis of user engagement. No major bugs were documented in this period; momentum was maintained through well-scoped configurations and instrumentation across AU and IN regions, with clear artifacts for ongoing experimentation and data reuse across future cycles.

July 2025

3 Commits • 2 Features

Jul 1, 2025

July 2025 — Delivered two key feature experiments in mozilla/metric-hub that drive measurable improvements in data collection and engagement analysis. Implemented enrollment data collection for the desktop-credit-card autofill global enablement holdback experiment via a TOML-configured query, and refined the data analysis scope by adjusting the date range and event tracking. Added new user activity segments for the Whats-new notification tab groups experiment to enhance targeting and insights into engagement with tab-group features. Impact: enables more accurate measurement of autofill adoption across global users and supports data-driven rollout decisions; improves segmentation-driven analytics for product engagement. Tech stack and skills demonstrated: TOML-configured data collection, experiment instrumentation, event tracking, and segmentation analytics.

June 2025

1 Commits • 1 Features

Jun 1, 2025

Monthly performance summary for 2025-06 focusing on delivering telemetry enhancements for Firefox Desktop, reinforcing data governance, and enabling richer analytics through Glean.

May 2025

1 Commits • 1 Features

May 1, 2025

Delivered New Toolbar iOS redesign Experiment (Iteration 1) in mozilla/metric-hub, configuring an A/B/n test named 'new-toolbar-ios-ios-redesign-iteration-1' with three weekly enrollment segments and data sources, including extraction of client IDs and enrollment dates from the event stream to quantify engagement during the experiment windows. No major bugs fixed this month. This work advances measurement-driven rollout decisions and strengthens instrumentation for iOS toolbar experiments.

March 2025

2 Commits • 2 Features

Mar 1, 2025

March 2025: Feature delivery and documentation improvements across two repos, enabling advanced experiment design and dot-release targeting for desktop experiments. Key outcomes include detailed preenrollment bias and covariate adjustment docs and Fx 136.0.2 targeting support, with related GraphQL/TypeScript and Docusaurus updates.

February 2025

1 Commits • 1 Features

Feb 1, 2025

February 2025 monthly summary for mozilla/bigquery-etl focused on ToS rollout analytics across Firefox platforms. Delivered new SQL views and metadata to monitor Terms of Service rollout enrollments across Fenix, Desktop, and iOS. Implemented derived tables to extract client_id, submission_timestamp, experiment_slug, and branch from event streams to enable tracking and analysis of ToS rollout experiments. This work was implemented as a single commit.

January 2025

6 Commits • 5 Features

Jan 1, 2025

January 2025 monthly summary for mozilla/metric-hub. This period focused on expanding telemetry coverage and experimentation capabilities through TOML-configured instrumentation, with emphasis on cross-device usage, onboarding cohorts, and promotional campaigns. Key outcomes include cross-device sign-in metrics on Windows, desktop-to-mobile adoption tracking, Jetstream multi-action CTA pin-tracking, extended onboarding observation windows, and onboarding add-ons promotions.

December 2024

4 Commits • 3 Features

Dec 1, 2024

December 2024 (Month: 2024-12) — Focused on data quality, experiment enablement, and telemetry robustness in mozilla/metric-hub. Delivered a data integrity fix for enrollment tracking and launched TOML-configured experiments to support controlled onboarding optimization, private-browsing VPN usage analysis, and account spotlight telemetry. These efforts increase metric accuracy, accelerate experimentation cycles, and provide actionable insights for product decisions.

November 2024

9 Commits • 7 Features

Nov 1, 2024

Month 2024-11 — Mozilla Metric Hub delivered 7 cross-platform experiment configurations and telemetry enhancements to accelerate data-driven improvements in onboarding, recommendations, import behavior, and the sync/backup value proposition. Key outcomes include expanded telemetry metrics (addon counts/installations, staff picks metrics using clients_daily data, import rates, pinned tabs events including pinning, concurrent pins, reloads), reorganization of experiment configurations for maintainability (moving configs out of outcomes folder and updating pinning metrics), and targeted onboarding experiments for iOS, Android, and Windows. These changes enable faster experimentation cycles, clearer data signals, and stronger business value around user activation, feature adoption, and data-informed product decisions. Notable commits include 57afab786fb16e9b02e0f408e7b67a94601d50d4, ed372dcd86f7f760e6634eb69292353ecff86726, 0d1cb76b2d46137210c538f8c4b5de1cee9d29be, 1439bd18307b8715703aeda92318c3ab1e81973f, 5727588576470ea8feabf301a0a9ed34bf579d35, 5cb62a8fb9b26936484187b0a39cd3440d29211a, 8abcf8a3b48e5d06578374e6002b96f0d494dd7b, 2f6d0e7dff836ec7e9c20f695de6054332810e4d

Activity

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Quality Metrics

Correctness94.8%
Maintainability95.2%
Architecture94.8%
Performance93.0%
AI Usage20.0%

Skills & Technologies

Programming Languages

GraphQLMarkdownPythonSQLTOMLTypeScriptjavascriptmarkdownsqltoml

Technical Skills

A/B Testing ConfigurationAPI Schema DefinitionBigQueryConfiguration ManagementData AnalysisData Analysis ConceptsData EngineeringData MetricsDocumentationExperiment ConfigurationExperiment ManagementExperimentationMetrics DefinitionMetrics TrackingRefactoring

Repositories Contributed To

4 repos

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

mozilla/metric-hub

Nov 2024 Apr 2026
9 Months active

Languages Used

SQLTOML

Technical Skills

Configuration ManagementData AnalysisData EngineeringData MetricsExperimentationRefactoring

mozilla/experimenter-docs

Mar 2025 Jan 2026
2 Months active

Languages Used

javascriptmarkdownsqltomlMarkdown

Technical Skills

Data Analysis ConceptsDocumentationTechnical WritingWeb Developmentdata analysisdocumentation

mozilla/bigquery-etl

Feb 2025 Feb 2025
1 Month active

Languages Used

SQL

Technical Skills

BigQueryData EngineeringSQL

mozilla/experimenter

Mar 2025 Mar 2025
1 Month active

Languages Used

GraphQLPythonTypeScript

Technical Skills

API Schema DefinitionConfiguration ManagementVersion Control