Rex
Rex is a YC Summer 2026 (S26) company. Based in San Francisco, CA, USA. Team of 2.
About Rex
Summary
Rex builds AI agents that run order-to-cash operations for enterprise finance teams, replacing the outsourced manual labor that sits between issued invoices and collected cash. The agents handle invoice submission, customer email correspondence, portal uploads, dispute triage, and payment application across the disconnected systems, handoffs, and exceptions that traditional automation cannot navigate. Finance teams get the throughput of a full BPO operation without the headcount.
Business model
A managed AI operations service priced as an alternative to outsourced BPO headcount.
Go-to-market
Enterprise finance teams at high-growth and pre-IPO tech companies are the primary buyers, engaging Rex as an operations partner rather than a software tool, with deployment focused on live receivables management from day one.
From the Y Combinator listing
AI-native BPO for enterprise order-to-cash
Rex is an AI-native service for order to cash. Rex replace manual operations with AI agents that continuously manage invoices, customers and exceptions. Order to cash is a $60B outsourced function because the work is too messy for traditional automation. Every customer has different context, exceptions do not follow clean rules, and the next step is often buried in emails, portals, handoffs, or someone’s memory. Rex agents run continuously in the background and resolve work to SLA standards so cash keeps moving. We're live with pre-IPO tech companies, managing >$500m in receivables from F100 companies, cutting manual follow-up cycles from weeks to hours. We founded Rex after spending four years building Sequence, an a16z-backed finance ops platform, from zero to Series A — where we saw firsthand that at-scale, O2C still runs on manual labour. Rex is the #1 winner of the Vercel AI Accelerator out of 2,500 teams, selected by Guillermo Rauch and leaders from OpenAI, Anthropic, Browserbase and more.
Facts
- B2B / B2B -> Finance and Accounting
- San Francisco, CA, USA
- 2
- Active
- Early
Founders (2)
- Lewis Blackwood
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