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Juliana J.JJ

Juliana J.

Supermalter

Senior Front-End Developer | React • TypeScript

€580/day
8 projects
Le Perray-en-Yvelines, FR
8-15 years

Average response time: 1 hour

Freelancer profile translated to English.
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About Juliana

I help product teams evolve their existing applications: refactoring, modular architecture, reusable components, testing, accessibility, and Product/UX collaboration.

Senior Front-End Developer with over 13 years of experience in software development, including over 8 years with React. I primarily work on applications already in production that need to evolve without a brutal rewrite.

I can assist you with:
- developing new React / TypeScript features
- progressively modernizing an existing front-end architecture
- separating business logic from the interface and reducing duplication
- building reusable components and integrating a Design System
- strengthening unit and end-to-end tests
- improving accessibility and maintainability
- collaborating with Product, UX, QA, Data, and Backend

I have worked on high-stakes products at beta.gouv.fr, SNCF Connect, Prose, PerfectStay, ManoMano, and Amundi.
My motivation is to contribute to products that bring real value to their users, while helping teams sustainably improve the quality and maintainability of their applications.

Expertise
React • TypeScript • JavaScript • Redux • Apollo GraphQL • Storybook • React Testing Library • Jest • Cypress • Playwright • Sass • Design Systems • Accessibility • Refactoring • Front-End Architecture • Code Review • Agile

📩Available for your Front-End projects
Looking for a React Front-End developer to strengthen your team or evolve your application? Let's discuss your project.

👨‍💻Github: github.com/JulianaJM
  • French

    Native or bilingual

  • English

    Fluent

Remote only
Primarily works remotely

Experience

  • Beta Gouv - DINUM
    Senior Front-End Developer - Trackdéchets
    PUBLIC SECTOR
    December 2022 - Today (3 years and 7 months)
    - Contribution to the progressive refactoring of the front-end architecture and to a more modular structure.

    - Participation in the progressive refactoring of the Front-End architecture to facilitate the integration of future developments.

    - Simplification of React components, separation of business logic and UI, reduction of duplication.

    - Preparation and progressive integration of the State Design System (DSFR).

    - Improvement of the ticket lifecycle and awareness of validation before production deployment.

    - Design workshops, quarterly roadmap seminars

    - Code reviews.

    Technologies: React, TypeScript, Apollo Client, GraphQL, Sass, Storybook, Testing Library
    React.js Front-End Development SASS Typescript JavaScript
  • Prose
    Senior Front-End Developer React
    FASHION AND COSMETICS
    July 2021 - May 2022 (10 months)
    - Proposal, from the technical test, to resume the questionnaire without loss of progress; functionality then developed in production.

    - Comparison of persistence solutions and implementation via Local Storage and Redux.

    - Co-design with PM, Proxy PO, UX, Backend, and Data team.

    - Participation in A/B tests of the prescription journey and Supplements pages under FlipT feature flags.

    - Code reviews

    Technologies: React, Redux, Styled Components, Jest, Cypress, FlipT
    React.js redux Front-End Development styled-components JavaScript
  • PerfectStay
    Front-End Developer React
    TRAVEL AND TOURISM
    January 2020 - March 2021 (1 year and 3 months)
    Paris, France
    - Development of React components and journeys for a white-label booking engine.

    - Integration of partners with a dedicated graphic identity on a common technical base.

    - Contribution to a White Label platform allowing rapid deployment of new brands from a common Front-End architecture.

    - UX, QA, Backend collaboration; validation on feature branch and strong e2e Cypress coverage.

    - Code reviews

    Technologies: React, Redux, Sass, Jest, Cypress, Zeplin
    React.js redux SASS JavaScript Responsive Design

Reviews

5.0

Out of 2 ratings

M

Mehdi

Développeuse Front-End - Trackdéchets

Reviewed on 6/18/2026

Juliana contributed with talent and dynamism to the Trackdéchets project during her assignment as a front-end developer. Her technical expertise, combined with great attention to detail and real creativity, helped shape a user interface that is both intuitive, performant, and polished. Her investment, responsiveness, and ability to collaborate effectively with the teams were valuable assets to the project. Thank you to Juliana for her valuable work.
E

Emmanuel

Trackdéchets

Reviewed on 10/22/2025

A big thank you to Juliana for the work she accomplished in implementing the dematerialization of hazardous waste traceability and the integration of National Register functionalities, nationwide, from December 2022 to date. Her commitment has led to wide recognition by industry players and has helped make Trackdéchets an innovative public project, emblematic of "State unicorns". As a Frontend Developer, she played a key role in the optimization and continuous improvement of the product's user interface. With a perfect mastery of best practices in accessibility, performance, and responsive design, she contributed to the functional evolution of the product. It's a pleasure to work with Juliana, her technical curiosity and attention to detail characterized each of her interventions.

Recommendations

Julien Seren-RossoJS
Julien K.JK
FU
Julien Seren-Rosso and 2 other people have recommended Juliana

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Education

  • State Diploma - Software Architect, Software Engineering
    INSTA
    2012
    Diplôme d'Etat - Architecte Logiciel, Ingénierie logicielle

Skill set

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