Freelancer profile translated to English.
Back to original languageAbout Thomas
Looking for a backend-oriented Ruby on Rails developer?
You've come to the right place.
I am a software engineer with over 15 years of experience.
My specialties: Ruby on Rails, PostgreSQL, Snowflake, Google Ads, web frontend interfaces.
I have worked in various sectors: fintech, adtech, greentech, e-commerce.
I have collaborated with companies such as Linedata, WiiSmile, Solocal, Sweep.
I am able to:
- Contribute to backend architecture decisions
- Challenge the existing, reduce technical debt
- Design backend services and Rails APIs (GraphQL, REST)
- Maintain large-scale systems (multi-tenant SaaS, 30,000+ clients)
- Synchronize large-scale data via API (Sidekiq + Kubernetes HPA)
- Reduce cloud infra costs through optimization and auto-scaling (GCP, Kubernetes HPA)
- Optimize SQL queries and search performance (Indexes, PostgreSQL Planner)
- Manage background jobs, monitoring, and observability (Sidekiq, SolidQueue, PGHero, Datadog)
- Operate OLAP analytical databases (Snowflake)
My notable achievements:
1. Data synchronization: 300M records/day, 3h -> 11mn (x16)
2. Reduction of infra and cloud costs: -50% GCP cost
3. Heavy migrations up to 40M records
I place great importance on the transparency of technical performance.
I implement automated dashboards to enable immediate incident detection and resolution.
Do you have a project?
Contact me
Response in 10 minutes
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French
Native or bilingual
English
Native or bilingual
Spanish
Native or bilingual
Arabic
Basic
Can work on-site
Lyon (up to 50km), Paris (up to 50km), Lyon (up to 50km), Bordeaux (up to 50km), Clermont-Ferrand (up to 50km)
Experience
- SweepRuby on Rails DeveloperSOFTWARE PUBLISHINGJanuary 2026 - Today (7 months)Sweep is a carbon footprint management software for large, high-emitting companies. Its objective: Collect, measure, and track their emissions to reduce them through concrete action plans (ESG).The company has 6,000 clients, 200 employees, 30,000 users.I joined the Pando team to participate in backend stabilization.The team consists of 5 senior Ruby on Rails backend engineers and 1 engineering manager.My responsibilities:- Improve backend performance: SQL queries, GraphQL endpoints, REST APIs, Snowflake- Add features to React screens- Reduce technical debt- Enable clients to access their billions of lines of OLAP data (Snowflake)- Configure Snowflake via Terraform- Maintain Datadog monitoring to anticipate and resolve issues before customer impactMain achievements:- Implemented GraphQL resolvers that reduced the execution time of complex GraphQL queries by 99% (10s → 100ms)- Implemented an export API for customer audit logs stored on Snowflake (billions of lines in 3 minutes)- Developed a data migration feature: Transferring millions of lines between different Postgres databases via CSV files, resolving data conflictsTechnical context:- Ruby on Rails- Sidekiq- React- GraphQL- PostgreSQL- Snowflake- OLAP- Datadog- AWS- Claude Code- AWS Bedrock- Backend developer- Backend developer- Backend ruby developer- Backend ruby on rails developer- Backend react developer- Back-end developer- Ruby On Rails Developer- Ruby on Rails Engineer- Ruby Developer- Software Engineer- Development Specialist
- SolocalRuby on Rails DeveloperPRESS AND MEDIAApril 2022 - December 2025 (3 years and 8 months)Clermont-Ferrand, FranceSolocal is a company specializing in digital advertising for professionals, enabling the automatic generation of advertising campaigns synchronized with Google, Bing, Yellow Pages, and Meta.The company has 2,000 employees and approximately 30,000 clients for this automated advertising offer.I joined the Effilab team of 8 people, including 4 senior developers, 100% English-speaking.My responsibilities:- Development and maintenance of legacy Rails applications that automatically generate advertising campaigns based on targeted professional activity- Synchronization of campaigns with Google, Bing, Yellow Pages, and Meta- Automatic download and transformation of advertising performance reportsMain achievements:- Optimization of data synchronization time between systems: 300 million records per day via GRPC API + HPA (Horizontal Pods Autoscaling).- Reduction from 3 hours to 11 minutes on average, thanks to optimization of processing time (+50% speed, -50% GCP cost) and the implementation of auto-scaled cloud parallelization- Elimination of slowdown peaks (up to 27 hours of latency before my intervention)- Migrations of large volumes of data (SQL tables with 40 million records)- Implementation of Metabase monitoring with alerting systems- Implementation of automatic assignment of functional errors to data entry operators for resolution.Technical context:- Ruby on Rails 8- Ruby 3.4- Sidekiq- PostgreSQL- PgHero- GraphQL- Google Ads API- Bing Ads API- Meta Marketing API- Vue 3- Vite- GCP- Kubernetes- HPA- Helm- Docker- Github- CircleCI- Metabase- Back developer- Backend developer- Backend ruby developer- Backend ruby on rails developer- Backend vue developer- Back-end developer- Ruby On Rails Developer- Ruby on Rails Engineer- Ruby Developer- Software Engineer- Development Specialist
- Woom.frRuby on Rails DeveloperE-COMMERCEMarch 2017 - December 2021 (4 years and 9 months)Clermont-Ferrand, Francewoom.fr is an e-commerce startup for leisure and vacation stays.The company had 6 employees and 3,000 leisure partners.Starting from scratch, woom.fr became one of the leaders in leisure in France in 3 years. Approximately 1,000 orders per month.In 2021, the platform was acquired by WiiSmile, a specialist in employee benefits.My responsibilities:- 3 sub-domains and 6 platforms, including a multi-tenant architecture- Full-stack development of the platform (backend, frontend, tests, infra)- Integration with Vente Privée (veepee.fr)- Mangopay 3DS2 and KYC tunnel integration- Customer.io integration- Rails 4.2 to 5.2 migrationMain achievements:- Implementation of an e-commerce purchase funnel with a 5% customer conversion rate, generating €1M annually- Performance optimization on all pages:- Display under 200 milliseconds- Google Lighthouse score of 90%Technical context:- Ruby on Rails- PostgreSQL- DelayedJob- Memcached/Dali- Algolia- Slim- SCSS- StimulusJS- Algolia InstantSearch JS- RSpec- Cucumber/Selenium- Gitlab CI- AWS S3- AWS SNS- AWS SES- Mangopay- Segment- OVH- Backend developer- Backend developer- Backend ruby developer- Backend ruby on rails developer- Backend react developer- Back-end developer- Ruby On Rails Developer- Ruby on Rails Engineer- Ruby Developer- Software Engineer- Development Specialist
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Education
- Master of Science in Computer Science, Networks and TelecommunicationsTélécom Bretagne2012
Certifications
- Engineering Diploma in Computer Science, Networks and TelecommunicationsTélécom Bretagne (IMT Atlantique, formerly ENST Bretagne)2012