Software Engineer II - Core Infrastructure

Full Stack Engineer · Mid · Full Time

US California (Redwood City) - OfficeUSD 165k – 220k2w ago
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Role

What you'll do.

Software Engineer II - Core Infrastructure at Poshmark is a full stack engineering role focused on building end-to-end seller experiences on the leading social fashion marketplace with 165 million members. This position requires 2-4 years of professional full stack engineering experience with proficiency in modern frontend frameworks like React and backend languages such as Ruby, Java, or Python, alongside strong computer science fundamentals. You'll own features across the complete technology stack—from database architecture to responsive user interfaces—collaborating with experienced engineers to ship products serving millions of sellers on Poshmark's scalable infrastructure.

Responsibilities

  • Full Stack Feature Development: Design, develop, and maintain production-quality full stack features supporting end-to-end seller experiences including listing creation, order management, and inventory management systems across responsive frontend interfaces and high-performance backend services.
  • Frontend Implementation: Build responsive, accessible, and performant user interfaces using modern frontend frameworks like React, Vue, or Angular with strong HTML, CSS, and JavaScript/TypeScript proficiency to ensure optimal seller experience across devices.
  • Backend Services Development: Develop and maintain scalable backend services and RESTful APIs that power seller-facing workflows, utilizing distributed systems, databases (SQL/NoSQL), and message-queue systems to handle millions of concurrent marketplace transactions.
  • Collaborative Engineering: Collaborate with senior engineers, product managers, QA specialists, and design team members to implement scalable, efficient, and maintainable systems architecture across the seller platform, participating actively in code reviews and technical discussions.
  • Code Quality and Testing: Write clean, well-documented, and thoroughly tested code following software engineering best practices, including comprehensive unit and integration tests, while continuously improving through peer feedback and code review processes.
  • Production Support and Troubleshooting: Troubleshoot and resolve issues across frontend and distributed backend systems in production environments, diagnosing complex technical problems and implementing data-driven solutions to maintain platform reliability and performance.
  • Performance and Scalability: Contribute to performance optimization initiatives and scalability improvements on both client and server sides, analyzing system architecture, identifying bottlenecks, and implementing solutions for the seller platform serving millions of users.
  • Development Process Improvement: Contribute to improving development processes, tooling, continuous integration/deployment workflows, and team development practices to enhance engineering velocity and code quality across the seller pod.

Qualifications

What we look for.

Technical

  • Full Stack Development Proficiency

    Demonstrated expertise building end-to-end web applications with both frontend and backend components, integrating user interfaces with backend services and managing data flow across the complete stack.

  • Frontend Framework Expertise

    Strong proficiency in at least one modern frontend framework (React, Vue, or Angular) with advanced HTML, CSS, and JavaScript/TypeScript skills to build responsive, performant user interfaces.

  • Backend Language Proficiency

    Production-level expertise in at least one backend programming language including Ruby, Java, JavaScript/Node.js, or Python with solid understanding of backend architecture patterns.

  • API and Database Knowledge

    Strong understanding of RESTful API design, SQL and NoSQL database systems, caching mechanisms, and message-queue systems for building scalable, performant backend services.

  • Computer Science Fundamentals

    Solid grasp of core computer science concepts including data structures, algorithms, time/space complexity analysis, and software design principles essential for writing efficient, maintainable code.

  • Responsive Web Development

    Proven experience building responsive, mobile-friendly web applications that provide optimal user experience across diverse devices and screen sizes using modern CSS techniques and responsive design patterns.

  • Version Control and Collaboration

    Proficiency with Git version control, code review workflows, and collaborative development practices essential for working effectively in team environments with distributed engineering teams.

  • Testing and Quality Assurance

    Experience writing comprehensive unit tests, integration tests, and utilizing testing frameworks to ensure code reliability and maintainability across frontend and backend components.

Education

  • Bachelor's Degree in Computer Science

    Bachelor's degree in Computer Science, Software Engineering, or closely related field providing foundational knowledge in algorithms, data structures, and system design.

  • Equivalent Practical Experience

    For candidates without formal CS degree, substantial demonstrated professional software engineering experience, completed online certifications, or portfolio projects demonstrating equivalent technical expertise and problem-solving capabilities.

Experience

  • Professional Full Stack Engineering Experience

    2-4 years of professional full stack software engineering experience including internships, demonstrating progressive responsibility in shipping production features and collaborating with engineering teams.

  • Commercial Web Application Development

    Hands-on experience building commercial web applications from concept to production, with demonstrated ability to handle technical requirements like scalability, performance optimization, and system reliability.

  • Cross-Stack Problem Solving

    Proven ability to troubleshoot and solve technical problems spanning both frontend and backend layers, including debugging distributed systems and optimizing system performance.

Skills

Required

  • React or Modern Frontend Framework

    Production-level expertise with React, Vue, Angular, or equivalent framework for building complex, performant user interfaces with component-based architecture.

  • JavaScript/TypeScript

    Advanced proficiency in JavaScript or TypeScript including ES6+ features, async programming, functional programming concepts, and modern JavaScript tooling.

  • HTML and CSS

    Strong HTML5 and CSS3 skills including semantic markup, responsive design, CSS Grid, Flexbox, and modern CSS techniques for building accessible, performant interfaces.

  • Backend Programming Language

    Production-level expertise in Ruby, Java, Python, JavaScript/Node.js, or equivalent backend language with solid understanding of language-specific frameworks and ecosystems.

  • RESTful API Design

    Strong understanding of REST principles, HTTP methods, status codes, API versioning, and best practices for designing scalable, maintainable APIs.

  • SQL and NoSQL Databases

    Practical experience with relational databases (PostgreSQL, MySQL) and NoSQL solutions (MongoDB, Redis), including query optimization, schema design, and indexing strategies.

  • Data Structures and Algorithms

    Solid understanding of common data structures and algorithms, including arrays, linked lists, trees, hashing, sorting, and dynamic programming with ability to analyze time and space complexity.

  • Version Control with Git

    Proficient use of Git for version control, including branching strategies, commit practices, pull requests, and collaborative workflows in team environments.

  • Web Development Best Practices

    Understanding of web performance optimization, accessibility standards (WCAG), security best practices, and responsive design principles for modern web applications.

Preferred

  • Cloud Platform Experience

    Nice to have

    Familiarity with cloud computing platforms such as AWS, Google Cloud Platform (GCP), or Azure, including services like EC2, Lambda, Cloud Functions, and containerization with Docker.

  • Caching and Message Queue Systems

    Nice to have

    Experience with distributed caching solutions (Redis, Memcached) and message queue systems (Kafka, RabbitMQ, AWS SQS) for building scalable asynchronous systems.

  • Microservices Architecture

    Nice to have

    Understanding of microservices design patterns, service-to-service communication, API gateways, and distributed system challenges including eventual consistency and fault tolerance.

  • E-commerce Platform Development

    Nice to have

    Experience building features for e-commerce or marketplace platforms, including product listing systems, order management, payment integration, or inventory management.

  • Social Commerce or Community Features

    Nice to have

    Background in social commerce, social networking features, or community-driven platforms with understanding of user engagement, social discovery, and shared experiences.

  • Performance Monitoring and Optimization

    Nice to have

    Experience with application performance monitoring tools, profiling, optimization techniques, and ability to measure and improve system and application performance metrics.

  • Agile Development Practices

    Nice to have

    Familiarity with Agile methodologies, Scrum, sprint planning, and iterative development practices common in fast-paced product development environments.

  • Testing Frameworks and Methodologies

    Nice to have

    Experience with testing frameworks (Jest, Mocha, JUnit, Pytest), test-driven development (TDD), and coverage analysis tools for comprehensive test suites.

Tech stack

Languages

JavaScript/TypeScriptPythonJavaRubySQL

Frameworks

ReactVue.jsAngularExpress.js or Node.js FrameworksRailsSpring or Spring Boot

Databases

PostgreSQLMySQLMongoDBRedis

Tools

GitDockerJest or MochaWebpack or VitePostman or Similar API Tools

Other

AWS or Cloud ServicesREST API ArchitectureMessage Queues and Event StreamingContinuous Integration/Continuous DeploymentSystem Design and Scalability

Compensation

Pay and benefits.

Base·USD 165,000 – 220,000

Benefits

  • Health and Wellness Coverage

    Comprehensive health insurance plans including medical, dental, and vision coverage to support your wellbeing and healthcare needs.

  • Flexible Work Environment

    Collaborative culture with flexibility to support work-life balance, fostering creativity and productivity in a fast-paced technology environment.

  • Professional Development

    Opportunities for continuous learning including mentorship from senior engineers, technical training, conference attendance, and career growth within engineering organization.

  • Competitive Compensation Package

    Competitive salary, performance bonuses, and potential equity grants aligned with experience and market rates for mid-level software engineers in Silicon Valley.

  • Impactful Work

    Opportunity to build features used by millions of sellers on a leading fashion marketplace, directly impacting business growth and seller empowerment across the platform.

  • Collaborative Engineering Culture

    Work alongside experienced engineers in a supportive environment prioritizing code quality, knowledge sharing, and collaborative problem-solving across the seller pod.

Full posting

Original listing.

About Poshmark


Poshmark is the leading fashion marketplace where style comes alive through discovery, self-expression, and human connection. Powered by a vibrant community of 165 million members, Poshmark brings real people and taste to shopping through a social experience shaped by shared discovery. Buying and selling fashion feels simple, joyful, and personal, while every item tells its own story. Poshmark empowers sellers to grow meaningful businesses, keeps fashion in circulation longer, and gives shoppers access to unique and trusted finds, from everyday pieces to one-of-a-kind vintage and luxury.

 

🎯 About the Role

We’re looking for a Full Stack Engineer to join our Seller Pod and help build the end-to-end experiences that power how sellers list, manage, and grow their businesses on our marketplace. You’ll work across the stack — crafting responsive, intuitive seller-facing interfaces on the frontend and reliable, high-performance services on the backend. This is an exciting opportunity to own features from the database to the browser, collaborate with experienced engineers, and ship products used by millions of sellers every day.

⚙️ What You’ll Do

Design, develop, and maintain full stack features that support the seller experience, from listing creation to order and inventory management.

Build responsive, accessible, and performant user interfaces using modern frontend frameworks.

Develop and maintain backend services and APIs that power seller-facing workflows.

Collaborate with peers and senior engineers to implement scalable, efficient, and maintainable systems across the stack.

Write clean, well-documented, and well-tested code following best practices.

Participate in code reviews and learn from feedback to continually improve.

Troubleshoot and fix issues across the frontend and distributed backend systems in production environments.

Contribute to improving development processes, tooling, and team workflows.

6-Month Accomplishments:

Become proficient with the seller pod’s tech stack, development tools, and codebase across frontend and backend.

Ship production-quality full stack features with guidance from senior team members.

Take ownership of small to medium-sized components or features end-to-end.

Collaborate effectively with Product, QA, and Design teams on feature delivery.

12+ Month Accomplishments:

Independently deliver full stack features from design to production.

Contribute to performance improvements and scalability initiatives on both the client and server side.

Develop a strong understanding of the seller platform’s system architecture and make data-driven technical decisions.

Participate in technical discussions and contribute ideas to improve platform reliability, usability, and efficiency.

Mentor interns or new hires joining the team.

💪 What You’ll Bring

2- 4 years of professional experience (including internships) in full stack software engineering.

Strong understanding of computer science fundamentals — data structures, algorithms, and software design principles.

Proficiency in a modern frontend framework (e.g., React, Vue, or Angular) and strong HTML, CSS, and JavaScript/TypeScript skills.

Proficiency in at least one backend language (e.g., Ruby, Java, Javascript or Python).

Familiarity with RESTful APIs, databases (SQL/NoSQL), and caching or message-queue systems.

Experience building responsive, user-facing web applications.

Interest in cloud technologies (AWS, GCP, or similar) and scalable architectures.

Bachelor’s degree in Computer Science or a related field, or equivalent practical experience.

Collaborative, curious, and motivated to learn and grow within a fast-paced environment.

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