Rex

AI Operations Partner for Enterprise Order to Cash

Y CombinatorSummer 2026ActiveB2BFinance and AccountingB2BEnterprise SoftwareAI

What they do

Problem

Enterprise order-to-cash operations are messy and exception-heavy, making invoice management and collections slow, manual, and hard to automate.

Solution

Rex provides AI agents that continuously run order-to-cash workflows to manage invoices, customers, and exceptions to SLA standards and keep cash moving.

Who it's for

Enterprises and high-growth companies with large accounts receivable teams managing significant B2B receivables from enterprise customers.

Founders

Lewis Blackwood

Founder

Founder and CTO at Rex, building the AI partner for enterprise order to cash. Previously: - Founding engineer at Sequence (backed by a16z) - Cofounded Personably (backed by Global Founders Capital) - Early team at GoCardless (YC S11) - Economics at Cambridge

Merlin Kafka

Founder

Merlin is the Founder and CEO of Rex, the AI partner for enterprise order-to-cash. He spent 4 years as CPO at Sequence (a16z-backed), an order-to-cash platform where he grew the company to millions in ARR and hundreds of customers. He has deep domain expertise in order to cash and accounts receivable workflows -- the exact space Rex is transforming with AI. Previously a PM at Tessian (Sequoia-backed, acquired in 2023). Studied Industrial Engineering in Cambridge and Product Design in Glasgow.

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