Elixir Developer Jobs in Philadelphia, PA (NOW HIRING)

CollX is changing the face of card collecting, bringing computer vision, machine learning, and other technology to the Hobby. We began by solving a very simple and age-old problem: helping collectors figure out what their cards are worth. The CollX app, launched in early 2022, enables anyone to snap a photo of a trading card, instantly ID it, and get the current market value. From there you can scan your collection, follow your friends, and buy, sell or trade with others. The app has quickly grown to more than 3.6M users, who have scanned over a billion cards.

We’re looking for a Senior Elixir Developer to join our growing team. We've hit the limits of horizontal scaling and batch processing. We're dealing with billions of entities, streaming data across auto-scaling clusters, and every architectural decision has real consequences. This isn't about building faster CRUD apps—it's about fundamentally different engineering challenges.

We’re Looking For Someone who:

• Has been here before. You've debugged distributed systems in production, planned migrations that can't have downtime, and built things that handle massive load.
• Has built systems that don't fit on one machine. You understand why consistent hashing matters, why you can't just "add more servers," and when eventual consistency is your friend (and when it's your enemy).
• Thinks in streams, not batches. Real-time data processing across distributed systems is your wheelhouse. You've debugged backpressure issues, dealt with partitioning strategies, and know why ordering guarantees are harder than they look.
• Has made the hard architectural choices. You understand the tradeoffs between consistency, availability, and partition tolerance—not just as theory, but as daily reality.

Our Stack & Scale

• Continuous deployment with zero-downtime requirements
• Billions of entities requiring careful data modeling
• Streaming architectures where batch processing isn't an option

• Design systems that work at scale. Every table change, every new feature requires serious architectural consideration. You'll be making decisions that affect performance and reliability for years to come.
• Support the software delivery lifecycle from design to implementation
• Collaborate with interdisciplinary teams to conduct automation testing and check for performance bottlenecks
• We’re a small company, so whatever else may come up that you can help with!

• Degree in Engineering, Computer Science (or equivalent experience)
• Mastery of Elixir
• Solid understanding of GraphQL
• 8+ years of relevant experience as a software developer
• Prior experience developing mobile applications is a plus
• Demonstrable experience in building marketplace facilitation systems is a plus
• Excellent communication and collaboration skills

• Be part of a small, nimble, and fast-growing company that’s reshaping the sports card industry.
• Work alongside passionate collectors, entrepreneurs, and industry leaders.
• See the impact of your work consistently and quickly, operating with increased autonomy and decision-making.