Senior/Staff Software Engineer

Extend
New York, NY

Extend is building a modern document processing platform, reimagined with LLMs. We're on a mission to transform how the world works with unstructured data.

As a Software Engineer at Extend, you’ll be responsible for building our core platform that companies use to configure, test, and deploy document processing. We’re looking to hire exceptional engineers who care about crafting intuitive product experiences, relentlessly focus on the details, and operate with high agency.

Why you should consider joining

  • We've grown revenue 15x this year to 7-figures in ARR, with our growth continuing to accelerate

  • We have a product loved by users and being used in mission-critical flows at companies like Chime, Flatiron Health, Brex, Opendoor, Checkr, and many more

  • We're building the next generation document processing platform — the market for document processing has expanded 1000x due to LLMs, and existing solutions are all low NPS

  • We're punching well above our weight, supporting customer and revenue metrics with half the team size of other startups — everyone joining at this stage will have outsized impact

  • We're looking for engineer #3 to join a very talent dense team (e.g. former founders, world record holders) operating in a high performance culture, in-person in NYC, with high equity ownership

  • We're tackling novel, unsolved problems at the intersection of LLMs, complex data processing, and human ↔ AI interfaces

  • We're backed by world class investors, including YC, Homebrew, investors from OpenAI, and more

  • You'll get a front row seat to how a successful startup is built with plenty of leadership opportunities as we grow quickly

We're a lean team, and our customer base is growing too fast for us to keep up. We're looking for talented engineers to join our founding team ahead of our next round and execute on an ambitious roadmap.

Impact

We're powering mission-critical data processing at companies where if we get things wrong, there are real world impacts (e.g. missed payments, people can't move into homes on time).

Here's a few of the complex technical problems we're working on:

  • How do we enable enterprises to deploy LLM-powered document processing into production with confidence?

  • How do we handle never before seen edge cases in customer data?

  • How do we build a self-correcting system that automatically gets better over time?

  • How do we enable non-technical domain experts to improve models with their expertise & business logic?

  • How do we help customers make tradeoffs between latency, cost, and performance?

  • How do we build reliable systems that can process large data streams in real-time?

Role

  • Build, and maintain, durable, scalable systems capable of processing 10s of millions of data points per month.

  • Design and implement the best human ↔ AI interfaces for designing and understanding document processing. We are building a new territory of UX that previously did not exist. It’s up to us to discover and implement new patterns that work for our users.

  • Have complete ownership over the work you do — as a founding team member, you’ll have the opportunity to truly own large areas of product and engineering and have direct relationship with customers.

  • Work directly with the CEO, CTO, and other founding members and help build out our team.

Ideal Candidate Credentials

  • 5+ years of experience building complex software systems in production environments

  • You've been at high-growth startups and know what "great" looks like

  • Ability to take abstract projects end-to-end, operating with high agency

  • Experience deploying AI/ML systems into production environments

  • Experience with developer tools is a plus

Posted 2026-01-16

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