Katalyz vs. Billabex: Which AI Collection Agent Should You Choose in 2026?

Updated May 14, 2026 · 9 min read

Katalyz.ai and Billabex are the two leading French AI-powered platforms for unpaid invoice collection. Both promise an intelligent agent that follows up with your debtors on your behalf. But the approaches are very different — in pricing, features, and philosophy. This comparison helps you decide.

Quick summary

Pricing: the fundamental difference

Katalyz: you only pay when it works

Katalyz.ai operates on a performance-based model. The commission only applies to amounts recovered beyond the debtor's usual payment delay. In plain terms: if your client normally pays at 45 days and ends up paying at 60 days thanks to the agent, the fee only covers the 45-60 day window. If the agent recovers nothing, you pay nothing.

This model aligns incentives: Katalyz wins when you win. It's particularly attractive for SMBs hesitant to invest in a tool whose results they haven't proven yet.

Billabex: fixed subscription, results or not

Billabex charges a monthly subscription starting at EUR 170 (excl. VAT) for the PRO plan (under 2,000 invoices per year). Whether the agent recovers a lot or nothing, you pay the same amount every month.

This model suits businesses with predictable invoice volumes who want a fixed budget. But for a micro-business with 10-20 overdue invoices per month, EUR 170/month can be a barrier — especially early on, when you don't yet know if the solution will deliver.

Real-world simulation

Take an SMB with 50 overdue invoices totaling EUR 75,000.

With Billabex: EUR 170/month, or EUR 2,040/year. Fixed cost regardless of results.

With Katalyz: if the agent recovers 85% (EUR 63,750), and the success fee is 10% on the portion recovered beyond usual delay (estimated at 40% of total, or EUR 25,500), the cost is EUR 2,550. Slightly more in this scenario, but you only paid because the agent actually recovered your money. If the agent recovers nothing, the cost is EUR 0.

AI voice calls: the Katalyz advantage

This is the most visible difference in 2026. Katalyz offers AI voice calls with a natural-sounding voice in French, English, and Arabic. When a debtor doesn't respond to emails, the agent picks up the phone, calls, negotiates in real time, and confirms payment agreements.

Billabex has announced this capability in its marketing, but it's not yet visible in the product. Collection through Billabex runs primarily via email, through its subsidiary Revoptim.

Why this matters: studies show that 30-40% of debtors who ignore emails respond to phone calls. Skipping the voice channel means leaving money on the table.

The Revoptim model

Billabex has a distinctive approach: follow-ups are sent in the name of Revoptim, its subsidiary which is a licensed collection agency. The agent signs as a "Client Relations Manager" at Revoptim, not in your company's name.

The upside: the third-party effect increases open and response rates. Receiving an email from a collection agency creates more urgency than one from your supplier.

The downside: your client knows they've been handed off to a third party. The business relationship can suffer. Some debtors experience this as aggressive escalation, even if the tone remains courteous.

Katalyz takes the opposite approach: the agent works in your name, with your brand, in the tone you define. The debtor thinks they're communicating with a team member. The relationship is preserved.

Multilingual: different approaches

Billabex advertises 80+ languages through AI translation. Impressive coverage, but the question is quality: is an auto-translated Arabic or Japanese message as impactful as a natively composed one?

Katalyz offers fewer languages (5+) but with a "native" approach: the agent doesn't translate, it communicates as a native speaker, accounting for cultural norms (formality in French, negotiation conventions in Arabic, directness in English). Quality over quantity.

Integrations: Billabex leads

On accounting integrations, Billabex has an edge. Beyond Pennylane and Sage, Billabex connects to NetSuite, Zoho Books, Chargebee, Odoo, and Sellsy. The Pennylane partnership is particularly strategic: it provides access to 6,000 accounting firms and 700,000 businesses.

Katalyz offers Pennylane, Sage, QuickBooks, Xero, and Stripe. The Stripe integration is notable for SaaS and e-commerce businesses looking to recover failed payments directly.

Who should choose what?

Choose Katalyz if...

You want a pay-for-performance model (zero risk, aligned incentives). You need AI voice calls for debtors who ignore emails. You work with international clients and want culturally adapted follow-ups. You prefer the agent working in your name (relationship preservation). You're a small business and EUR 170/month is a significant commitment.

Choose Billabex if...

You prefer a fixed, predictable budget. You want the third-party pressure of Revoptim. You need integrations with NetSuite, Zoho, or Chargebee. You're already in the Pennylane ecosystem (native integration). You have high volume and want a capped cost.

Our take

Both platforms address a real need. Billabex has the advantage of being earlier to market (launched 2024) and a broader integration ecosystem. Katalyz has the advantage of innovation (AI voice calls) and a pricing model better aligned with SMB interests.

For many SMBs, the deciding factor will be pricing. Pay EUR 170/month with no performance guarantee, or pay only when the agent actually collects? For businesses just starting out or still evaluating, Katalyz's success-fee model reduces risk to zero.