Sr. Software Engineer Core Infrastructure

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.

The Core Infrastructure team drives developer experience, microservice development, and performance and reliability related initiatives. Developer experience covers anything that a team might need in order to build, release, run, and support software; for example, ensuring automated tests stay fast and stable. Poshmark's first platform was largely a monolith written in JRuby. Today that monolith is being broken up into smaller microservices written in Java, JRuby, and Python. The Core Infrastructure team develops the microservice frameworks and core libraries used by other teams.

Responsibilities:

• Write high‑quality code in Ruby (JRuby), Java, and Python

• Develop APIs, frameworks, libraries and services for use by other developers

• Design and improve architecture in order to ensure horizontal scalability at all layers

• Resolve issues related to performance at all tiers of the application

• Help shape developer experience a.k.a. engineering enablement at Poshmark, including defining what best practices every team should be following

• Use AI as a force multiplier in day-to-day engineering work

• Closely partner with the DevOps, security, and SRE teams to bake compliance, performance, and reliability into the platform

6-Month Accomplishments:

• Able to plan medium complexity projects with no supervision

• Provides meaningful design feedback and code reviews to peers

• Actively mentors junior engineers, guiding them through complex technical tasks and fostering their career development

12+ Month Accomplishments:

• Able to find technical solutions to large complexity problems with minimal supervision

• Able to identify architectural gaps and propose solutions

• Have rolled out a high impact project to production

Desired Skills:

• 4+ years experience building and operating back-end systems

• You have experience debugging complex problems across an entire stack

• You have worked on and/or understand distributed systems and large scale engineering challenges

• You are familiar with either NoSQL or SQL databases and have experience scaling them

• You are a strong communicator who can articulate trade‑offs and drive consensus across teams

• Experience with any of: Ruby (JRuby), Java, Python, MongoDB, OpenSearch, Redis, RabbitMQ, containerization, and *nix environments

• A solid foundation in computer science with strong competencies in data structures, algorithms, and software design