CrawlJobs Logo
Yopeso Logo Yopeso · IT - Software Development

Full-Stack JavaScript Engineer

Spain, Madrid · Job Posted May 04, 2026
Apply Position
Job Link Share

Job Description

We are seeking an experienced Full Stack Developer to join our team working on an open-source AI chat platform. The successful candidate will contribute to developing and maintaining a sophisticated conversational AI application that integrates multiple AI providers and offers a rich user experience, while collaborating closely with product and design stakeholders.

Job Responsibility

  • Develop and maintain both frontend and backend components of the AI chat platform
  • Implement new AI provider integrations and chat functionalities
  • Work with modern React-based frontend and Node.js/Express backend architecture
  • Collaborate on database design and optimization using MongoDB
  • Implement and maintain real-time features using WebSocket connections
  • Write comprehensive tests and ensure code quality through automated testing
  • Deploy and maintain containerized applications using Docker
  • Participate in code reviews and maintain high development standards

Requirements

  • React.js (v18+) with modern hooks and functional components
  • TypeScript for type-safe development
  • Vite for build tooling and development server
  • TailwindCSS for styling and responsive design
  • Radix UI and Headless UI for accessible component libraries
  • Tanstack Query (React Query) for data fetching and state management
  • React Router for client-side routing
  • State management with modern React patterns
  • Node.js (v18+) with Express.js framework
  • MongoDB with Mongoose ODM for database operations
  • PostgreSQL structured data storage
  • Redis for caching and session management
  • RESTful API design and implementation
  • JWT and session-based authentication
  • Docker and Docker Compose for containerization
  • MongoDB database administration
  • Environment configuration and secrets management
  • Git with advanced workflows (rebasing, merging, conflict resolution)
  • ESLint and Prettier for code quality
  • 3+ years of full-stack JavaScript/TypeScript development
  • Fluent in English, both written and verbal
  • Excellent communication and collaboration skills
  • Ability to work independently and manage complex projects

Nice to have

  • Experience with OpenAI API, Anthropic Claude, or similar LLM APIs
  • Understanding of prompt engineering and AI model integration
  • LangChain framework for AI application development
  • RAG (Retrieval-Augmented Generation) implementation experience
Yopeso - All Job Offers

Looking for more opportunities?

Search for other job offers that match your skills and interests.

Suggested Tags: Frontend Developer Secretary Talent Manager Salesforce Administrator Data Analyst
Similar Jobs for

Full-Stack JavaScript Engineer

8 matching positions

Full-Stack JavaScript Engineer

We are seeking an experienced Full Stack Developer to join our team working on a...
Location
Location
Spain , Madrid
Salary
Salary:
Not provided
yopeso.com Logo
Yopeso
Expiration Date
Until further notice
Flip Icon
Requirements
Requirements
  • Frontend Development: React.js (v18+) with modern hooks and functional components
  • TypeScript for type-safe development
  • Vite for build tooling and development server
  • TailwindCSS for styling and responsive design
  • Radix UI and Headless UI for accessible component libraries
  • Tanstack Query (React Query) for data fetching and state management
  • React Router for client-side routing
  • State management with modern React patterns
  • Backend Development: Node.js (v18+) with Express.js framework
  • MongoDB with Mongoose ODM for database operations
Job Responsibility
Job Responsibility
  • Develop and maintain both frontend and backend components of the AI chat platform
  • Implement new AI provider integrations and chat functionalities
  • Work with modern React-based frontend and Node.js/Express backend architecture
  • Collaborate on database design and optimization using MongoDB
  • Implement and maintain real-time features using WebSocket connections
  • Write comprehensive tests and ensure code quality through automated testing
  • Deploy and maintain containerized applications using Docker
  • Participate in code reviews and maintain high development standards
Read More
Arrow Right

Senior Full-Stack JavaScript Engineer – Rapid Clinical Prototyping

At Boston Children’s Hospital, the quality of our care – and our inclusive hospi...
Location
Location
United States , Boston
Salary
Salary:
83241.60 - 133192.80 USD / Year
childrenshospital.org Logo
Boston Children's Hospital
Expiration Date
Until further notice
Flip Icon
Requirements
Requirements
  • Bachelor’s in Computer Science, Bioinformatics, Engineering, Mathematics, or related discipline
  • 4 years of experience in a professional work environment outside of academic or educational settings or Master’s in 2 years of experience
  • Professional experience with NodeJs, HTML, React, CSS, SQL and other technologies used in web development
  • Strong proficiency with front-end development and data visualization using Javascript
  • At least one other programming language (Python preferred)
  • Comfortable doing basic system administration in a Linux environment to deploy applications
  • Strong communication and collaboration skills
  • Excellent problem-solving ability, collaborative spirit, and scientific curiosity
Job Responsibility
Job Responsibility
  • Researches and identifies the requirements of software development and application programming needs
  • Analyzes vendor, internally developed, and open source solutions to meet the integrated needs ranging the spectrum of artificial intelligence and biomedical informatics
  • Specifies, designs, develops, codes, tests, and implements software that support the needs of multiple projects considering the individual goals and objectives of each entity
  • Participates in leading the creation and maintenance of standards for development and software selection and makes software development process and design recommendations within the department or program and to project stakeholders
  • Provides analytical and technical guidance to team members and stakeholders
  • Identifies requirements, develops software design, codes, plans, and executes testing, and ensures that the software delivered meets specifications
  • Creates systems development life cycle documents and/or assists team members in the creation of project documents
  • Produces written documentation for new and existing processes, programs, code, applications, and workflow
  • Keeps software documentation accurate and up to date
  • May assist team members in software administration and maintenance, including preparing and reviewing reports for operations, senior management, and stakeholders
What we offer
What we offer
  • flexible schedules
  • affordable health, vision and dental insurance
  • child care and student loan subsidies
  • generous levels of time off
  • 403(b) Retirement Savings plan
  • Pension
  • Tuition and certain License and Certification Reimbursement
  • cell phone plan discounts
  • discounted rates on T-passes
  • Fulltime
Read More
Arrow Right

Senior Full-Stack JavaScript Engineer

We are looking for passionate people who enjoy working in a team-oriented enviro...
Location
Location
United States
Salary
Salary:
Not provided
sitepen.com Logo
SitePen
Expiration Date
Until further notice
Flip Icon
Requirements
Requirements
  • Senior full stack engineer with at least 10 years of full-time experience
  • Very experienced in delivering Enterprise Software (SaaS, IaaS, etc.)
  • Effective communicator with Product and Business teams
  • Able to provide examples of scalable, performant code
  • Confident in preferred architectures and tools
  • Committed to code quality, ownership & accountability
  • Passionate about the web platform
  • Interested in learning new technologies, standards, and techniques
  • Self-disciplined, able to work and communicate effectively in a fully remote environment
  • Able to lead and delegate when needed
Job Responsibility
Job Responsibility
  • Write new web applications for our customers
  • Provide upgrades and fixes to our customers' existing apps
  • Provide technical assistance and support for our customers' development teams
  • Participate in coaching, training, and leveling up other developers
  • Contribute patches and enhancements to many open source projects
  • Enjoy a refreshing work-life balance
  • Fulltime
Read More
Arrow Right

Senior React Engineer (Full-Stack Focus)

We are seeking an experienced Senior React Developer to join a collaborative Agi...
Location
Location
United States , Maple Grove
Salary
Salary:
Not provided
Intellias
Expiration Date
Until further notice
Flip Icon
Requirements
Requirements
  • 5–7+ years of professional software development experience
  • Strong React development experience (mandatory)
  • Experience with React Redux
  • Strong JavaScript and TypeScript skills
  • Experience building enterprise-scale web applications
  • Strong understanding of front-end architecture and component design
  • Experience working with .NET Core backend environments
  • Strong API development and integration experience
  • Experience consuming and integrating RESTful services
  • SQL experience
Job Responsibility
Job Responsibility
  • Design, develop, and maintain modern web applications using React and TypeScript
  • Build scalable, reusable front-end components and application architecture
  • Collaborate with backend developers working within a .NET Core environment
  • Develop and integrate RESTful APIs across front-end and backend systems
  • Mentor and support developers who are growing their React expertise
  • Help establish front-end engineering standards, best practices, and development patterns
  • Participate in code reviews, technical discussions, and Agile ceremonies
  • Write clean, maintainable, and testable code
  • Support unit testing efforts across front-end and backend integrations
  • Work effectively within projects that may contain evolving requirements and ambiguity
  • Fulltime
Read More
Arrow Right

Software Engineer, Full-Stack

Ema, a Series A startup founded by serial entrepreneurs and ex-Google, Coinbase,...
Location
Location
United States , San Francisco Bay Area
Salary
Salary:
135000.00 - 300000.00 USD / Year
ema.co Logo
Ema
Expiration Date
Until further notice
Flip Icon
Requirements
Requirements
  • Bachelor's degree in Computer Science, Web Development, or a related field, or equivalent work experience
  • A minimum of 4 years of professional experience in full-stack development, with a focus on front-end engineering and API integration
  • Strong proficiency in HTML, CSS, and JavaScript, with extensive experience in React
  • Experience with gRPC for client-server communication, and familiarity with RESTful APIs, JSON, XML, and OAuth
  • Solid understanding of back-end technologies such as Node.js or Python, and experience working with server-side frameworks (e.g., FastAPI, Express)
  • Familiarity with version control systems like Git and build/deploy platforms such as Vercel
  • Excellent problem-solving and analytical skills, with a strong commitment to delivering high-quality user experiences across both front-end and back-end
  • Strong communication and collaboration skills, with the ability to work effectively both independently and as part of a team
Job Responsibility
Job Responsibility
  • Design, develop, and implement exceptional user interfaces for web applications using modern web technologies such as HTML, CSS, and JavaScript
  • Collaborate closely with product managers, UX designers, and other stakeholders to gather requirements, own the user experience, develop wireframes, and create high-fidelity prototypes
  • Develop and maintain API integrations, ensuring seamless communication between front-end and back-end systems using React and gRPC
  • Contribute to back-end development with a focus on creating robust APIs and ensuring smooth communication between the front-end and server using technologies like Node.js or Python
  • Build, test, and deploy full-stack web applications using React and gRPC, while ensuring responsiveness, performance, and scalability
  • Optimize web applications for performance, accessibility, and SEO best practices
  • Troubleshoot and resolve UI and back-end related issues, ensuring a consistent and optimal user experience across multiple platforms and devices
  • Write clean, maintainable, and well-documented code adhering to established coding standards, and deploy/debug using platforms like Vercel
  • Fulltime
Read More
Arrow Right

Lead Software Engineer (Full-stack)

We are looking for an experienced, passionate Full Stack Engineer to join our de...
Location
Location
United States , South Jordan
Salary
Salary:
Not provided
cricut.com Logo
Cricut
Expiration Date
Until further notice
Flip Icon
Requirements
Requirements
  • BS/MS in Computer Science or commensurate industry experience
  • 7-10+ years of professional experience in software development
  • Highly proficient in Angular 16+, TypeScript, JavaScript, HTML5, CSS3 (and preprocessors like Less/Sass)
  • Strong experience in C# / .NET for backend development
  • Experience designing and implementing RESTful APIs
  • Familiarity with cloud-based web services (AWS preferred) and Relational/Non-relational databases
  • Experience with Electron or similar desktop wrappers is a strong plus
  • Ability to design and develop reusable front-end components
  • Proficient in Test Driven Development (TDD), automated testing, and CI/CD pipelines
  • Deep knowledge of concurrency, resiliency, caching, and scalable software architecture
Job Responsibility
Job Responsibility
  • Design and develop scalable, high-performance web and desktop applications using Angular 16+, TypeScript, and Electron
  • Build and maintain robust backend services and RESTful APIs using C#/.NET and cloud-native technologies (AWS)
  • Collaborating across cross-functional teams (UX, QA, Product) to deliver new functionality for Cricut’s next-generation apps
  • Write solid, testable code for multiple platforms (Web, Windows, MacOS)
  • Participate in architectural discussions, guiding best practices for both frontend and backend systems
  • Solve real-world problems for users and ensure systems handling billions of transactions remain performant and reliable
  • Mentor junior engineers and contribute to a culture of continuous improvement
What we offer
What we offer
  • competitive Medical, Dental, and Vision coverage
  • a 401(k) match
  • generous PTO
  • tuition reimbursement
  • a yearly lifestyle stipend
  • exclusive employee discounts
  • Fulltime
Read More
Arrow Right

Senior Software Engineer Full-Stack

We are looking for a Senior Full-Stack Software Engineer with a background in cr...
Location
Location
United States , Lancaster
Salary
Salary:
Not provided
kodiak.ai Logo
Kodiak Robotics
Expiration Date
Until further notice
Flip Icon
Requirements
Requirements
  • Strong technical background as evidenced by BS, MS, or equivalent experience, in Computer Science or a related engineering discipline
  • 5+ years of experience building backend services and/or intuitive web applications with significant scale and performance
  • Solid understanding of HTML, CSS, and related web technologies
  • Recent experience with JavaScript, TypeScript and React
  • Experience with using internal and external facing APIs
  • Experience with app profiling and performance tuning.
  • Experience with service performance measurement, observability, and tuning.
  • Familiarity with web sockets and Typed Arrays
  • Great communicator
  • you must be capable of writing clear, concise, and detailed documentation.
Job Responsibility
Job Responsibility
  • Optimize and enhance existing applications and APIs to incorporate new features and user feedback.
  • Design new features and user experiences, including UI elements and layout through mockups (e.g., Figma) and implement such features in React + TypeScript.
  • Research and design new APIs for new use cases and implement such APIs and backend logic using Python, JavaScript/TypeScript, C++.
  • Utilize a variety of AWS technologies such as API Gateway, AWS Lambda, Amazon AppSync, DynamoDB, and Terraform.
  • Interact with a variety of data sources including documents, databases, raw and/or processed sensor data, and other APIs.
  • Collaborate with Software Engineering, Software Quality, and Operations to understand end user requirements.
What we offer
What we offer
  • Competitive compensation package including equity and annual bonuses
  • Excellent Medical, Dental, and Vision plans through Kaiser Permanente, Cigna, and MetLife (including a medical plan with infertility benefits)
  • MetLife Legal Services, Identity & Fraud Protection, Hospital Indemnity Insurance, Accident Insurance, & Critical Illness Insurance
  • Flexible PTO, 10 paid holidays, and generous parental leave policies
  • Office perks: free catered lunch, a fully stocked kitchen
  • Long Term Disability, Short Term Disability, Life Insurance
  • Wellbeing Benefits - Headspace through Cigna, Calm through Kaiser, One Medical, Gympass, Spring Health through Cigna, Rula (mental health navigation)
  • Fidelity 401(k)
  • Commuter, FSA, Dependent Care FSA, HSA
  • Various incentive programs (referral bonuses, patent bonuses, etc.)
  • Fulltime
Read More
Arrow Right

Lead Software Engineer (Full-Stack)

Do you love building and pioneering in the technology space? Do you enjoy solvin...
Location
Location
United States , Chicago
Salary
Salary:
179400.00 - 204700.00 USD / Year
capitalone.com Logo
Capital One
Expiration Date
Until further notice
Flip Icon
Requirements
Requirements
  • Bachelor’s Degree
  • At least 4 years of experience in software engineering (Internship experience does not apply)
  • At least 1 year experience with cloud computing (AWS, Microsoft Azure, Google Cloud)
Job Responsibility
Job Responsibility
  • Lead a portfolio of diverse technology projects and a team of developers with deep experience in distributed microservices, and full stack systems to create solutions that help meet regulatory needs for the company
  • Share your passion for staying on top of tech trends, experimenting with and learning new technologies, participating in internal & external technology communities, mentoring other members of the engineering community
  • Collaborate with digital product managers, and deliver robust cloud-based solutions that drive powerful experiences to help millions of Americans achieve financial empowerment
  • Utilize programming languages like JavaScript, Java, HTML/CSS, TypeScript, SQL, Python, and Go, Open Source RDBMS and NoSQL databases, Container Orchestration services including Docker and Kubernetes, and a variety of AWS tools and services
What we offer
What we offer
  • performance based incentive compensation, which may include cash bonus(es) and/or long term incentives (LTI)
  • comprehensive, competitive, and inclusive set of health, financial and other benefits that support your total well-being
  • Fulltime
Read More
Arrow Right