Rex

AI-native BPO for enterprise order-to-cash

3.0Score#353 of 999 agents#13 of 27 in Billing and collections agent

Why it ranks #353

Rex, an AI billing and collections agent from YC S26, ranks #353 of 999 AI agents and #13 of 27 in Billing and collections agent, with a score of 3.0 of 10. Data as of 3 Oct 2026.

The score adds four parts, each 0 to 10, by weight. Every point comes from public evidence. How scoring works ·

Proof 0 × 30% 0.0
Scale 1 × 30% 0.3
Momentum 6 × 25% 1.5
Autonomy 8 × 15% 1.2
= 3.0

Proof
Do customers use it? 30% of the score
0
No public claims of customers or revenue yet.
Not found: revenue or growth (+4), named customers (+3), a customer result (+2), a customer count (+2), work done at scale (+2)
Scale
Is there a real company behind it? 30% of the score
1
2 people.
- +1
  2 people on its YC page2 people
Not found: funding round in its news (+3)
Momentum
Is it shipping and growing now? 25% of the score
6
Shows a recent launch, hiring and a new batch.
- +3
  Launched in the last 6 monthsRex: Turn enterprise order-to-cash into an autonomous operationLaunch YC post · 27 Jul 2026
- +2
  Hiring: 2 open rolesFounding AI Engineer (Enterprise Finance Operations), Finance Operator in Residence (Order-to-cash)YC page
- +1
  New: YC Summer 2026
Not found: new traction claim in the last 6 months (+2), funding news in the last year (+2)
Autonomy
How much of the job does it do on its own? 15% of the score
8
Autonomous worker: completes whole tasks; people handle exceptions.
- +8
  Level 3 of 4: Autonomous workerCompletes whole tasks; people handle exceptions.
What the model read
- Acts in other systems: 90% likely
- Finishes whole tasks: 68% likely
- Calls itself an agent: 97% likely
- An AI-native service: it sells the finished work, so it counts as an agent at any level
Level 3: Completes whole tasks; people handle exceptions.

About Rex

Rex is an AI-native service for order to cash. Rex replaces 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.