Callixte is currently unavailable
Callixte Girard
Verified Expert in Engineering
Full-stack Developer
Paris, France
Toptal member since May 13, 2025
Bio
Callixte is a senior full-stack developer with over five years of experience across diverse industries, including legaltech, solartech, hiretech, FMCG, and real estate. He excels at building robust, scalable applications while adhering to SOLID principles and clean architecture. Clients particularly value Callixte's commitment to bug-free deliverables, transparent reporting, and pragmatic approach to software development that balances technical excellence with business needs.
Portfolio
LegalPlace
React, NestJS, Node.js, TypeScript, PostgreSQL, TypeORM, GitLab, GitLab CI/CD...
Revolt.eco
React, Next.js, Node.js, TypeScript, PostgreSQL, Git, GitHub, JavaScript...
Kador.io
React, Next.js, Node.js, JavaScript, PostgreSQL, MongoDB, Full-stack, Front-end...
Experience
- React - 6 years
- Node.js - 5 years
- TypeScript - 5 years
- Python - 5 years
- PostgreSQL - 5 years
- Next.js - 4 years
- Cursor AI - 2 years
- NestJS - 1 year
Preferred Environment
React, Next.js, NestJS, TypeScript, JavaScript, Python, PostgreSQL, Cursor AI, Git, Agile, Web3, Crypto
The most amazing...
...thing I've developed is an all-in-one recruitment application suite that reduced the hiring time of internal account managers by up to 50%.
Work Experience
React/Node.js Developer
2025 - PRESENT
LegalPlace
- Developed and shipped new features on a NestJS back end and a React front end while ensuring performant, accessible UIs for complex financial workflows.
- Designed and maintained robust RESTful APIs to integrate with external banking partners and internal legal service modules.
- Collaborated daily with product managers, UX designers, and adjacent engineering squads to align on data models, authentication flows, and deployment strategies.
- Established and evangelized best practices, including test-driven development (TDD), code reviews, shared documentation, and CI/CD pipelines.
- Utilized and shared my knowledge of AI-driven tools like code-assist and automated test generation to boost developer productivity without compromising code quality.
- Drove continuous improvement of development processes through retrospectives, metrics tracking, and knowledge-sharing workshops.
Technologies: React, NestJS, Node.js, TypeScript, PostgreSQL, TypeORM, GitLab, GitLab CI/CD, Agile, Scrum, Storybook, RTK Query, Cursor AI, Unit Testing, Jest, API Integration, TanStack Router, TanStack, User Interface (UI), Databases, Front-end Development, Back-end Development, Full-stack Development, Tailwind CSS, Software Architecture, CSS, APIs, Banking as a Service (BaaS), Amazon Web Services (AWS), HTML, Large Language Models (LLMs), Pixel Perfect, Responsiveness, Artificial Intelligence (AI), PL/pgSQL, Pipelines, Microservices, GraphQL, REST, CSS3, CSS Animations, Figma, CSV, REST APIs, Serverless, Gemini, Google Cloud Platform (GCP), .NET, Go, AI Tools, Non-relational Databases, Relational Databases, Claude, Active Directory (AD), Azure SQL Databases, Jira REST API, Java, BigQuery, Springbot, Laravel, DevOps, C#, Bubble, Low Code, React Hook Form, Single Sign-on (SSO), React Testing Library, Server-side Rendering (SSR), Object-oriented Programming (OOP), Amazon Simple Queue Service (SQS), Datadog, HIPAA Compliance, Payload CMS, RabbitMQ, Radix UI, Sitecore, WCAG 2, Mapbox, Geospatial Data, Automation, Google Workspace APIs, Salesforce API
Full-stack Developer
2024 - 2024
Revolt.eco
- Developed new features on the Vue/React/Next.js/C# application.
- Achieved rapid and bug-free feature delivery by adhering to industry best practices.
- Evolved a PostgreSQL database using Prisma for seamless migrations.
- Collaborated on determining the optimal approach for implementing significant changes.
- Reviewed code contributed by other developers during pull requests.
Technologies: React, Next.js, Node.js, TypeScript, PostgreSQL, Git, GitHub, JavaScript, Front-end, Back-end, Full-stack, Databases, RTK Query, Cursor AI, Unit Testing, Jest, TanStack Router, TanStack, User Interface (UI), Front-end Development, Back-end Development, Full-stack Development, Tailwind CSS, CSS, APIs, Dashboards, HTML, Vue, Large Language Models (LLMs), Pixel Perfect, Responsiveness, Material UI, Artificial Intelligence (AI), PL/pgSQL, Microservices, Chart.js, REST, D3.js, CSS3, CSS Animations, Figma, CSV, REST APIs, Gemini, CI/CD Pipelines, BigQuery, C#, Architecture, Single Sign-on (SSO), Docker, React Testing Library, Object-oriented Programming (OOP), Amazon Simple Queue Service (SQS), Radix UI, Sitecore, Mapbox, C#.NET, Airtable, Automation
React/Node.js Developer
2021 - 2023
Kador.io
- Developed the front and back end using Vue, React, Next.js, C#, and .NET.
- Participated in and facilitated user exchange sessions following Agile methodology to comprehend their needs and address inquiries.
- Migrated the application's database to PostgreSQL.
- Migrated the existing app from low-code platforms using Retool for the front end and Xano for the back end and database.
- Set up CRON jobs to define regular automated background actions and procedures.
- Utilized Retool occasionally for rapid prototyping and drafting purposes.
- Enhanced, restructured, and improved the existing monolithic and sluggish Retool and Xano application.
- Developed a Chrome extension for LinkedIn, complementary to the main app, in Vanilla JavaScript without external libraries.
Technologies: React, Next.js, Node.js, JavaScript, PostgreSQL, MongoDB, Full-stack, Front-end, Back-end, REST, Retool, Xano, Chrome Extensions, API Integration, TanStack Router, TanStack, User Interface (UI), RTK Query, Databases, Front-end Development, Back-end Development, Full-stack Development, Jest, Tailwind CSS, Software Architecture, CSS, APIs, Dashboards, OpenAI API, HTML, Vue 3, Large Language Models (LLMs), Pixel Perfect, Responsiveness, Material UI, Artificial Intelligence (AI), Supabase, PL/pgSQL, FastAPI, CSS3, CSS Animations, Figma, Figma to React, CSV, REST APIs, Google Cloud Platform (GCP), Serverless Framework, AI Tools, Non-relational Databases, Relational Databases, .NET, Active Directory (AD), Java, BigQuery, Laravel, Architecture, React Hook Form, Payload CMS, Radix UI, WCAG 2, Vue, C#, .NET 8
React/Python Developer
2021 - 2022
Needl
- Implemented the matchmaking algorithm between buyers and suppliers.
- Set up React applications with the Next.js framework to manage registrations and recommendations for CSMs, facilitating their client management.
- Studied and optimized the process of registration and animation of business meeting virtual events.
- Studied and implemented a key business data visualization app for stakeholders.
- Participated in integrating the matchmaking algorithm and data processing scripts on AWS Data Lab in collaboration with a data engineer.
- Prototyped solutions with Retool to provide a quick way for CSMs to see and modify key business data for their clients.
Technologies: React, Next.js, Python, Django, JavaScript, SQL, MySQL, Full-stack, Front-end, Back-end, Data Analysis, Pandas, NumPy, Retool, Git, Unit Testing, Pytest, API Integration, TanStack Router, TanStack, User Interface (UI), RTK Query, Databases, Front-end Development, Back-end Development, Full-stack Development, Tailwind CSS, Software Architecture, CSS, APIs, Analytics, Dashboards, Amazon Web Services (AWS), HTML, Pixel Perfect, Responsiveness, Material UI, Pipelines, Flask, REST, Snowflake, AWS Lambda, CSS3, Figma, Figma to React, Shadcn, CSV, REST APIs, Data Transformation, Serverless, Gemini, Google Cloud Platform (GCP), Serverless Framework, CI/CD Pipelines, Claude, Azure SQL Databases, Laravel, C#, Low Code, Docker, Server-side Rendering (SSR), Object-oriented Programming (OOP), HIPAA Compliance, Sitecore, Airtable, Google Workspace APIs, Salesforce API
Python Developer
2021 - 2021
sundayapp
- Developed a web scraper in Python to collect data from several thousand restaurants.
- Sorted all the data found in the interesting website pages containing new prospective restaurants, including pictures.
- Analyzed and matched this data against an existing database of tens of thousands of entries using the Pandas library.
Technologies: Python, Scraping, Web Scraping, Back-end, Data Matching, Pandas, Selenium WebDriver, Data Analysis, Back-end Development, CSV, Data Transformation
Python Developer
2020 - 2021
French Real Estate Agency
- Developed a scraper to collect real estate data from French cities such as MeilleursAgents. MeilleursAgents is a very challenging site to scrape due to the numerous protective measures they have explicitly implemented against scrapers.
- Stored and updated this data in a PostgreSQL database.
- Visualized the scraped data in a Power BI dashboard.
Technologies: Python, Django, PostgreSQL, SQL, Scraping, Full-stack, Database Design, Selenium WebDriver, Microsoft Power BI, Data Analysis, Unit Testing, Pytest, API Integration, User Interface (UI), Databases, Front-end Development, Back-end Development, Full-stack Development, Software Architecture, CSS, APIs, Analytics, Dashboards, HTML, REST, FastAPI, CSS3, CSV, REST APIs, Data Transformation
React Developer
2020 - 2020
ISEP
- Parsed JavaScript code initially with an AST to generate a comprehensive plan outlining its structure.
- Transformed the plan into colored visual blocks using the Blockly library.
- Converted each code section, including loops, conditions, variables, etc., into a block that could be rearranged and nested.
Technologies: React, JavaScript, Abstract Syntax Trees (AST), Full-stack, Front-end, Blockly, User Interface (UI), Front-end Development, CSS, HTML
VBA Developer
2017 - 2019
Bouygues Telecom
- Calculated statistics to analyze and optimize an order database.
- Developed corrective scripts for Excel database extracts to rectify inconsistencies automatically.
- Imported and merged various Excel extracts from BO databases.
- Presented results in a structured, clear format to be understandable to the entire non-tech team.
Technologies: Excel VBA, Excel 2013, Analytics, Data Visualization, Dashboards, Data Transformation, Google Cloud Platform (GCP), PHP
Experience
Vadims.AI —The AI That Understands Your Audience to Make Your Content Convert
Vadims.AI is a SaaS (software as a service) I co-founded with a friend in late 2024 and launched in early 2025.
This is a simple AI-based SaaS that allows influencers to write posts that correspond to their style and structure very easily and quickly. Users have nothing to configure; we fine-tuned the AI models for them. Users can also provide additional parameters and examples of their style to make the output even more fine-tuned. Everything is made to simplify their life and make it the easiest way possible.
There is a whole range of output formats provided, each with its specific format, codes, etc: high-value post, side note, tweet, Instagram description, LinkedIn post, newsletter, thread, and even more to come. This was made with Next.js, React, PostgreSQL, and deployed on Vercel. I also included a back office for my partner to update the detailed custom prompts and instructions for our models.
I made all the technical design and realization, while my partner made all the marketing and sales parts. We made the product part together, from a common and iterative reflection. I am also in charge of all the technical support, code coverage, security, and migrating the database while not affecting users in production.
This is a simple AI-based SaaS that allows influencers to write posts that correspond to their style and structure very easily and quickly. Users have nothing to configure; we fine-tuned the AI models for them. Users can also provide additional parameters and examples of their style to make the output even more fine-tuned. Everything is made to simplify their life and make it the easiest way possible.
There is a whole range of output formats provided, each with its specific format, codes, etc: high-value post, side note, tweet, Instagram description, LinkedIn post, newsletter, thread, and even more to come. This was made with Next.js, React, PostgreSQL, and deployed on Vercel. I also included a back office for my partner to update the detailed custom prompts and instructions for our models.
I made all the technical design and realization, while my partner made all the marketing and sales parts. We made the product part together, from a common and iterative reflection. I am also in charge of all the technical support, code coverage, security, and migrating the database while not affecting users in production.
Full-stack Development
http://revolt.eco• Developed new features on the Vue/React/Next.js/C# application.
• Achieved rapid and bug-free feature delivery by adhering to industry best practices.
• Evolved a PostgreSQL database using Prisma for seamless migrations.
• Collaborated on determining the optimal approach for implementing significant changes.
• Reviewed code contributed by other developers during pull requests.
• Achieved rapid and bug-free feature delivery by adhering to industry best practices.
• Evolved a PostgreSQL database using Prisma for seamless migrations.
• Collaborated on determining the optimal approach for implementing significant changes.
• Reviewed code contributed by other developers during pull requests.
React/Python Development
• Implemented the matchmaking algorithm between buyers and suppliers.
• Set up React applications with the Next.js framework to manage registrations and recommendations for CSMs, facilitating their client management.
• Studied and optimized the process of registration and animation of business meeting virtual events.
• Studied and implemented a key business data visualization app for stakeholders.
• Participated in integrating the matchmaking algorithm and data processing scripts on AWS Data Lab in collaboration with a data engineer.
• Prototyped solutions with Retool to provide a quick way for CSMs to see and modify key business data for their clients.
• Set up React applications with the Next.js framework to manage registrations and recommendations for CSMs, facilitating their client management.
• Studied and optimized the process of registration and animation of business meeting virtual events.
• Studied and implemented a key business data visualization app for stakeholders.
• Participated in integrating the matchmaking algorithm and data processing scripts on AWS Data Lab in collaboration with a data engineer.
• Prototyped solutions with Retool to provide a quick way for CSMs to see and modify key business data for their clients.
Education
2014 - 2019
Master of Engineering Degree in Software Development
ISEP - Paris, France
Skills
Libraries/APIs
React, Node.js, OpenAI API, Vue, REST APIs, Jira REST API, React Hook Form, React Testing Library, Google Workspace APIs, Salesforce API, Pandas, Selenium WebDriver, Vue 3, Chart.js, NumPy, Blockly, Stripe API, D3.js
Tools
RTK Query, TanStack Router, Claude, BigQuery, Git, GitHub, Retool, Prisma, Pytest, Jupyter, Figma, Shadcn, Bubble, Amazon Simple Queue Service (SQS), RabbitMQ, GitLab, GitLab CI/CD, Microsoft Power BI, Excel 2013
Languages
TypeScript, JavaScript, Python, SQL, HTML, PL/pgSQL, GraphQL, Go, Java, PHP, C#, CSS, CSS3, Excel VBA, Snowflake, C#.NET
Frameworks
Next.js, Jest, Tailwind CSS, Serverless Framework, .NET, Laravel, Payload CMS, NestJS, Django, Material UI, Flask, .NET 8
Paradigms
Clean Code, Clean Architecture, REST, Unit Testing, DevOps, Object-oriented Programming (OOP), Automation, Agile, Database Design, Scrum, Microservices, HIPAA Compliance
Platforms
Google Cloud Platform (GCP), Docker, Xano, Vercel, Amazon Web Services (AWS), AWS Lambda, Mapbox
Storage
PostgreSQL, Databases, Relational Databases, Azure SQL Databases, Datadog, MongoDB, MySQL
Other
Software Development, SOLID Principles, Front-end, Back-end, Full-stack, Scraping, Web Scraping, GitHub Actions, API Integration, TanStack, User Interface (UI), Front-end Development, Back-end Development, Full-stack Development, Software Architecture, APIs, Large Language Models (LLMs), Responsiveness, CSV, Gemini, CI/CD Pipelines, AI Tools, Non-relational Databases, Active Directory (AD), Springbot, Single Sign-on (SSO), Server-side Rendering (SSR), Sitecore, WCAG 2, Airtable, Cursor AI, Hexagonal Architecture, Data Analysis, Analytics, Data Visualization, Web3, Dashboards, Banking as a Service (BaaS), Pixel Perfect, Artificial Intelligence (AI), Pipelines, FastAPI, Figma to React, Data Transformation, Serverless, Architecture, Low Code, Radix UI, Geospatial Data, TypeORM, Storybook, Chrome Extensions, Data Matching, Abstract Syntax Trees (AST), Crypto, Supabase, Vectors, CSS Animations
Collaboration That Works
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
1
Share your needs
Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2
Choose your talent
Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3
Start your risk-free talent trial
Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.
Top talent is in high demand.
Start hiring