Software Engineer, Backend (Staff+)

About the role

ABOUT LIGHTFIELD

Lightfield is reimagining CRM as a world model of a business. By learning from emails, meetings, and customer conversations, we’re building a living understanding of how a company works—so AI can help teams anticipate what comes next, make better decisions, and take action.

More than 5,000 companies have used the product since its November launch. We’ve raised more than $70M from Andreessen Horowitz, Coatue, Maverick Ventures, and Greylock to attack the biggest software category in the world. We previously built Tome, which reached more than 25 million users, and our team brings experience from Llama, Instagram, Google, and Salesforce.

ABOUT THE ROLE

At Lightfield, the backend is not a layer beneath the product. It is the product's foundation.

Lightfield builds a living model of a company's customers from emails, calls, meetings, and other signals. It structures that raw history into customer-defined objects, attributes, relationships, and versioned values, then exposes the same underlying capabilities to the product UI, external APIs, automations, and agents. Decisions about the data model, authorization, event propagation, and execution semantics directly determine what customers can do.

As a Software Engineer, Backend, you'll own those decisions for important product capabilities. You'll start with an ambiguous customer or product problem, define the behavior and system boundaries, design the data model and APIs, sequence migrations, and carry the capability through rollout and production. Recent examples include record-level permissions, field history and audit, durable workflows, and consumption metering.

These foundations already operate at meaningful scale:

- Our Postgres fleet serves 5B+ queries a month — roughly 2,500 QPS steady state, with sustained spikes past 25,000 QPS — and database workload more than doubled last month.

- Redis sustains ~50,000 commands per second behind a job platform that executes 10M+ background job runs a day across ~170 queues.

- We ingest tens of millions of emails and calendar events a month.

Scale makes the product work technically serious: new abstractions must be fast, reliable, observable, and safe under real load. But this is not primarily a role for keeping the lights on. It's a chance to define foundational pieces of an AI-native product while the architecture is still taking shape—and to see those decisions change what customers and agents can accomplish.

This role can be based in San Francisco or Cambridge. In San Francisco, you'd work from our HQ alongside the founders and most of the engineering team. In Cambridge, you'd join an initial group of staff-level engineers at our new Kendall Square site, working alongside one of our most senior infrastructure engineers. We aim to build the site and organization around this group as the company scales.

WHAT YOU'LL DO

- Own core product capabilities end to end—from customer requirement and behavioral semantics through data model, API, migration, rollout, and operation.