Rex
New accelerator entry · 2026-05-27 · the record
In their words
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.
What the record says
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.
Founders, titles and bios as the company published them. Photographs are our own copies of the ones on that record, so they do not break when the original link expires.
Against the 209 companies on file from Summer 2026. Median team 2, largest 30.
The nearest companies on file from the same batch, side by side with this one.
| Company | Batch | Sectors | Listed |
|---|---|---|---|
| Frontier Computing | Summer 2026 | Artificial Intelligence, Hard Tech, Hardware | 2026-08-31 |
| Ethos Space Resources | Summer 2026 | Hard Tech, Exascale Computing, Energy | 2026-08-23 |
| Spectre Intelligence | Summer 2026 | Biotech, Investing, Trading | 2026-08-22 |
| Edgerun | Summer 2026 | Robotics, Defense | 2026-08-21 |
| Allia Health | Summer 2026 | Artificial Intelligence, Healthcare, Mental Health | 2026-08-19 |
| Rex (this page) | Summer 2026 | Artificial Intelligence, B2B, Enterprise | 2026-05-27 |
Click a column heading to sort. Comparison is against records held here, not against every company that exists.
The full profile
The rest of this profile is open on any paid or trial plan
It costs no credits. It is a plan check and nothing else.
- Source Check — verify Merlin Kafka's other claims against the registers that hold them.
- INVEST — compare this company against the peers above, on the numbers.
- RECRUIT — see who is already on the team.
- Press Requests — connect with Merlin Kafka for a story.
You land back on this company when you are in.
Not ready to upgrade? Keep this one in view instead.
Watchlist RexYou get an alert in MentionFox the next time this company shows up.
Is this you?
If you're behind Rex: acceptance into a YC batch is one of the few weeks a young company gets looked up by people who matter — investors, other founders, press. FoxPlug turns the commits, deploys, and releases you're already making into that story automatically, so anyone who looks finds something current. FoxChat puts a guide on your own site so the people YC's own page just sent you don't read one line and leave.
Sourced from the company's Y Combinator directory entry. Figures are read directly from the source record; names have not been matched against other people.