Free to start. No contract. We'll show you what your finance stack is costing you.
The problem
An AI product has a cost of goods on every request
Traditional SaaS runs at 80–90% gross margin because serving one more user is nearly free. An AI product pays for inference on every request, so its gross margin runs lower and moves with usage — ICONIQ's State of AI report put AI product gross margin at 45% in 2025. A flat subscription priced on the average user loses money on the heavy ones; Anthropic added weekly limits to its $200 Max plan in 2025 after some subscribers ran tens of thousands of dollars of usage on it. The fix is pricing that follows cost — tokens, requests, agent runs or credits — and a billing system that can meter and invoice it.
UK software companies are in the same move: in m3ter and PwC's 2026 survey of 350 UK software executives, 34% already run pay-per-use alongside traditional pricing and half changed pricing twice or more in a year. Every change has to reach the invoice — with VAT in sterling on each one — without a migration.
Gross margin · by customerFlat £200 plan
Median customercost to serve £31
84%
Top decilecost to serve £412
−106%
Blended
46%
What Fynex runs
How AI billing runs on Fynex
Meter the cost driver, price it, cap it, collect it.
AI usage metering
Meter tokens, requests and agent runs
Register a metric per cost driver — input tokens, output tokens, model requests, agent executions, GPU seconds — with the aggregation that fits it. Events carry an idempotency key and arbitrary metadata such as the model, so a retry from your gateway never bills twice.
Hybrid pricing
Hybrid plans: platform fee, allowance, overage
A recurring platform or seat fee with an included allowance and graduated overage above it, on one contract. Change the overage rate from next month as a dated price version; last month's invoices keep the price they were billed on.
AI-token credits
Credits for AI tokens, with spend caps
Sell prepaid AI-token credits, grant promotional credit on sign-up, and set a spend cap per customer so a runaway agent loop can't produce a bill nobody agreed to. Alerts fire at the threshold you choose, before the cap.
Margin visibility
Margin per customer, not just revenue
Put what each customer costs to serve beside what they pay, and see which plan a heavy-usage cohort has outgrown. Fynex recommends the price change — it never applies one without your approval.
Cohort · top decile
Revenue
£38,400
Inference cost
£29,100
Recommendedoverage above 2M tokens
Review
How we compare
The same job, with the leaks closed
Point tools solve part of it. Fynex runs the whole thing on one platform.
The problem
Other platforms
Recommended
!Meter tokens and agent runs
✕Other platformsA metering engine (Orb, Metronome) plus a separate processor.
✓FynexMetering, rating and invoicing in one engine, collected on the same record.
!Sell AI credits
✕Other platformsCredit burn-down supported; the wallet sits apart from the money.
✓FynexCredit ledger with AI-token credits, applied after tax, liability exported.
!Stop a runaway bill
✕Other platformsAlerts, then a support ticket after the invoice.
✓FynexPer-customer spend caps and threshold alerts before the invoice.
!See gross margin per customer
✕Other platformsExported to a BI tool and joined with the cloud bill.
✓FynexCost to serve beside revenue, with a recommended next price for your approval.
!Independence
✕Other platformsMetronome is now part of Stripe; Orb became part of Adyen in 2026.
✓FynexProcessor-neutral: keep your processor, add billing, payouts and reconciliation.
FAQ
Questions, answered
Most AI companies in 2026 bill hybrid: a recurring platform or seat fee that includes an allowance, plus usage above it priced on the cost driver — tokens, requests or agent runs — often sold as prepaid credits. The billing system has to meter those events accurately, rate them, cap spend, apply credit and issue an invoice the customer can check.
The common shortlist is Stripe Billing, Fynex, Metronome, Orb, Amberflo and Lago. Stripe Billing with Metronome (acquired January 2026) suits Stripe-native companies; Fynex meters, invoices and collects on one record with payouts and reconciliation included; Orb targets high-volume AI and infrastructure; Amberflo focuses on LLM cost metering; Lago is open source for teams that self-host. Compared side by side: the best usage-based billing platforms.
Credits give the customer a predictable spend and give you cash before the cost; pure usage follows cost exactly but produces variable invoices. Many AI products combine them: a subscription with included credits, pay-as-you-go above, and a spend cap. Fynex supports all three on one contract, so switching models is a price change, not a re-platform. See prepaid credits billing and usage-based billing.
Price the unit that drives inference cost, include an allowance sized to the median user, charge graduated overage above it, and cap spend so outliers can't run unbounded. Then watch cost to serve against revenue per customer and cohort. Fynex meters and prices the usage, applies the cap, and surfaces which customers cost more to serve than they pay — the agentic finance layer on top of the rate card.
B2B services to EU businesses are generally outside UK VAT with the customer accounting for VAT under the reverse charge; B2C digital services to EU consumers carry the consumer's local VAT from the first sale through the non-Union OSS. UK customers are charged UK VAT above the £90,000 registration threshold. Fynex invoices enforce the fields each case requires, including reverse-charge wording and the VAT total in sterling.
Keep building
The rest of the billing layer
Every guide below runs on the same billing engine and the same money. Start with one, or run the whole stack.
We can be your Merchant of Record and hold the funds. Most tools can't, because they don't hold the licence.
FCA-authorised EMI
An e-money institution via Fondy. We can hold and move your funds.
Licence
E-money institution
FCA
Client funds
Safeguarded
PCI DSS Level 1
The highest card-data security standard, on by default.
Card data
PCI DSS
Level 1
Encryption
On by default
Audit logs
Every movement traceable and ready for review.
Activity
Payout · £23,84714:02:11
Logged
Split · ORD-2024-00114:02:09
Logged
Built-in KYC / KYB
The switch that turns the business on.
Verification
KYB · Northwind Labs Ltd
Approved
KYC · J. Whitfield
Approved
We do Fridays so you don't have to.Payouts at midnight. You, asleep.Invoices that chase themselves. Ruthlessly.We carry the chargebacks. You carry on.We do Fridays so you don't have to.Payouts at midnight. You, asleep.Invoices that chase themselves. Ruthlessly.We carry the chargebacks. You carry on.We do Fridays so you don't have to.Payouts at midnight. You, asleep.Invoices that chase themselves. Ruthlessly.We carry the chargebacks. You carry on.
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