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Tomi Katajanheimo

PROFILE

Tomi Katajanheimo

Over 18 months, contributed to Opetushallitus/ataru and kouta-backend by building and refining backend features focused on data privacy, workflow reliability, and internationalization. Delivered enhancements such as robust data anonymization pipelines, CSV-driven ingestion, and payment obligation review synchronization, using Clojure, SQL, and JavaScript. Improved system integrity through type-safe data handling, cache optimization, and security upgrades, while integrating services like AWS and eIDAS authentication. Emphasized maintainability with targeted refactoring, comprehensive test automation, and clear API boundaries. The work addressed evolving compliance needs, streamlined user-facing processes, and ensured accurate, multilingual data flows across complex application and review lifecycles.

Overall Statistics

Feature vs Bugs

76%Features

Repository Contributions

73Total
Bugs
11
Commits
73
Features
35
Lines of code
551,547
Activity Months18

Work History

June 2026

1 Commits

Jun 1, 2026

June 2026 monthly summary for Opetushallitus/ataru focused on targeted data integrity improvements and clean test coverage. Delivered a critical type-safety fix for the Finnish Social Security Number field and reinforced end-to-end data handling with accompanying tests and validations.

May 2026

4 Commits • 3 Features

May 1, 2026

2026-05 monthly highlights for Opetushallitus/ataru focusing on three core outcomes: delivering precise Finnish SSN handling, improving communications for eIDAS-authenticated users, and refining UI/error message translations. This period emphasizes data accuracy, user guidance, and maintainability, with changes mapped to specs and utilities for long-term reliability.

April 2026

7 Commits • 4 Features

Apr 1, 2026

April 2026 — Delivered four core features in Opetushallitus/ataru with a strong emphasis on test automation, authentication compliance, and user experience improvements. The work enhanced reliability, security posture, and business value through faster feedback loops and clearer user guidance.

March 2026

2 Commits • 2 Features

Mar 1, 2026

March 2026 monthly summary: Delivered two key features across Opetushallitus repositories, focusing on internationalization and backend connectivity. The Ataru project gained a Multilingual Label Comparison Enhancement (Finnish and Swedish) to improve label filtering accuracy by using language-specific keys. The Kouta-backend project adopted the AWS Advanced JDBC Wrapper to enhance database connectivity and configuration options. No major bugs fixed this month. These changes reduce label misclassification risks, streamline deployments, and lay groundwork for scalable, multi-language support across the platform. Technologies demonstrated include language-aware filtering, i18n improvements, AWS JDBC Wrapper integration, and Java backend work, with clear commit traceability.

February 2026

2 Commits • 1 Features

Feb 1, 2026

February 2026 monthly summary for Opetushallitus/ataru: Delivered reliability and observability improvements to critical workflows, focusing on anonymization stability and discretionary applications processing.

January 2026

2 Commits • 1 Features

Jan 1, 2026

January 2026 monthly summary for Opetushallitus/ataru: Delivered cross-review synchronization for kk-application-payment-obligation to ensure consistency across related reviews on save. Implemented the new behavior and accompanying tests, improving data integrity and accelerating the review workflow.

December 2025

2 Commits • 1 Features

Dec 1, 2025

2025-12 Monthly performance summary: Delivered key enhancements across two repos with a focus on correctness, maintainability, and clear API boundaries. Activities included a bug fix in kouta-backend for sports vocational training location eligibility and a feature improvement in ATARU's CAS client for header handling; both backed by targeted commits and tests, yielding measurable business value and improved developer ergonomics.

November 2025

4 Commits • 1 Features

Nov 1, 2025

November 2025 monthly performance summary focusing on delivering the Payment Obligation Review Enhancements for the Opetushallitus/ataru repository, with strengthened workflow, improved state management, and clearer status labeling across the payment review process.

October 2025

3 Commits • 1 Features

Oct 1, 2025

October 2025: Opetushallitus/ataru delivered user-focused localization improvements and robust data retrieval fixes, driving better user experience and more reliable payment flows.

September 2025

8 Commits • 5 Features

Sep 1, 2025

September 2025 monthly summary focusing on business value and technical achievements across Opetushallitus/kouta-backend and Opetushallitus/ataru. Highlights include security hardening via CAS upgrade, resource optimization with singleton client patterns, enhanced payment obligation lifecycle, and internationalization improvements that improve user experience and reporting.

August 2025

18 Commits • 6 Features

Aug 1, 2025

August 2025 monthly summary for Opetushallitus/ataru: Delivered a set of reliability, performance, and compliance-focused enhancements across access control, email handling, payments, and UI. Notable outcomes include: doubled daily payment status checks without blocking main processing, extended email retention, improved email delivery reliability with deduping and clearer errors, enhanced observability to aid debugging, and UI/performance improvements for KK application searches. Data sanitization improvements and post-rebase code cleanup reduced risk and technical debt. These changes collectively enhance business value by reducing support incidents, improving payment processing timeliness, ensuring regulatory retention, and delivering faster, more reliable user experiences.

June 2025

6 Commits • 2 Features

Jun 1, 2025

June 2025 monthly summary for Opetushallitus/ataru focusing on feature delivery, security validation, and performance improvements. Key work included attachment deadline handling and configuration enhancements, input validation for malicious input, and cache performance optimization for institutional data. The work emphasized business value, reliability, and maintainability with targeted tests and refactors.

May 2025

3 Commits • 2 Features

May 1, 2025

May 2025 monthly summary for Opetushallitus/ataru. Key features delivered include Email Service Integration (viestinvälityspalvelu) with updated dependencies, configuration, and refactoring to pass organization OIDs and metadata for privilege control and masking. Also implemented Dual Study Program Key Updates to support new identifiers and preserve data integrity. Major bug fixed: attachment-deadline service parameterization ensuring the attachment-deadline-service is passed to email job processing and application service calls, preserving email generation and event handling. Impact: improved reliability, security, and scalability of outbound communications; better support for evolving program structures and data integrity; smoother end-to-end processing workflows. Technologies/skills demonstrated: backend service integration with a new messaging service, dependency/configuration management, data model evolution (organization OIDs, new dual study keys), and robust parameter propagation across services.

April 2025

2 Commits • 1 Features

Apr 1, 2025

April 2025: Opetushallitus/ataru monthly performance summary emphasizing business value and technical achievements. Focus areas include data retrieval optimization for applications and a new API to fetch application OIDs by hakukohde OIDs, enabling downstream processing and analytics.

March 2025

3 Commits • 1 Features

Mar 1, 2025

March 2025 performance summary for Opetushallitus/ataru focusing on business value and technical achievements. Key feature delivered: Ineligibility Reason Handling for Export and Review, consolidating ineligibility reason logic across Excel export and review notes. Changes ensure the Excel export shows reasons only for ineligible applications, review notes are cleaned when an application is no longer ineligible, and outdated ineligibility notes are removed across systems (export and transfer API). This work was implemented via the following commits: 743cf8715bc06953460bbc8206569ee8f0363dea; c3b98de1c0060026c2f6e6c058b6ac24beed26a8; d3a54b451c01a7a0eee43c72f10866083ed994f0 (OY-5079).

February 2025

1 Commits • 1 Features

Feb 1, 2025

February 2025 highlights for Opetushallitus/ataru: Implemented auto-fill of missing contact details (email, phone, address) using ONR data, accompanied by helper utilities for de-accenting and normalizing strings and generating contact data from available person information. This work improves data completeness and quality, reduces manual data entry, and enhances outreach capabilities. Linked to commit OY-4954: Generate contact details if not present in ONR data.

January 2025

4 Commits • 2 Features

Jan 1, 2025

January 2025 (Opetushallitus/ataru): Delivered core anonymization pipeline enhancements and data integrity fixes, targeting CSV-based data ingestion, orphaned-data cleanup, and atomic batch encryption/anonymization workflows. These changes improve privacy compliance, data integrity, and processing reliability while enabling CSV-driven data flows for anonymization tasks.

December 2024

1 Commits • 1 Features

Dec 1, 2024

Month 2024-12: Delivered a key privacy and data handling enhancement in Opetushallitus/ataru by refactoring the anonymization pipeline to support additional fields, including long text areas and guardian information. Updated core anonymization logic and SQL queries to improve coverage and robustness, ensuring sensitive information is properly anonymized and compliant with privacy requirements. This work reduces risk of data exposure and lays groundwork for safer analytics across applications data.

Activity

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Quality Metrics

Correctness88.2%
Maintainability86.2%
Architecture82.6%
Performance82.6%
AI Usage20.6%

Skills & Technologies

Programming Languages

CSSClojureClojureScriptHTMLJavaJavaScriptLESSSQLScalaShell

Technical Skills

API DevelopmentAPI IntegrationAPI developmentAWSBackend DevelopmentCSV ParsingCache ManagementClojureClojure DevelopmentClojure developmentClojureScriptCode CleanupCode RefactoringConfiguration ManagementData Anonymization

Repositories Contributed To

2 repos

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

Opetushallitus/ataru

Dec 2024 Jun 2026
18 Months active

Languages Used

ClojureSQLJavaTypeScriptCSSClojureScriptHTMLJavaScript

Technical Skills

Backend DevelopmentClojure DevelopmentData AnonymizationDatabase ManagementSQL ScriptingCSV Parsing

Opetushallitus/kouta-backend

Sep 2025 Mar 2026
3 Months active

Languages Used

JavaScalaXML

Technical Skills

Backend DevelopmentDependency ManagementScalabackend developmentdatabase managementtest-driven development