SaaS per-seat
Examples
SlackLinearNotionFigmaCursor
How it works
Per-user monthly/annual, mid-cycle quantity changes, trials
API building blocks
seat product · quantity · automatic proration
SEPA · E-Invoicing · Subscription Billing
Billing for Europe.
Finally done right.
A billing platform built for the regulatory reality of 27 member states, at the speed modern product teams expect.
One platform for every billing model SaaS per-seatAPI platformHybrid PaaSMarketplaceSubscription BoxDomain RegistrarTelco CarrierCloud InfrastructureCreator PlatformEnterprise SaaSReseller NetworkOutcome-Based ServicesSaaS per-seatAPI platformHybrid PaaSMarketplaceSubscription BoxDomain RegistrarTelco CarrierCloud InfrastructureCreator PlatformEnterprise SaaSReseller NetworkOutcome-Based ServicesSaaS per-seatAPI platformHybrid PaaSMarketplaceSubscription BoxDomain RegistrarTelco CarrierCloud InfrastructureCreator PlatformEnterprise SaaSReseller NetworkOutcome-Based Services
3 hrs
Average integration time to the first production invoice.
1 tenant
One instance for DACH, Benelux, Nordics and EU-wide subsidiaries.
< 200ms
p99 billing API latency across all EU regions, measured from Frankfurt.
01 · Foundation
Depth that wins every demo.
Seven points that matter during evaluation – built for the requirements of European finance teams, not adapted from US products.
Tax Engine
For every edge case in Directive 2006/112/EC.
Reverse charge, OSS, IOSS, margin scheme, small-business exemption. Rules are versioned and fully traceable in the audit log.
2,184 tax rules active27 member states
E-Invoicing
XRechnung, ZUGFeRD, Peppol BIS 3.0.
Validation against official Schematron rules, automatic mapping from your raw data, handoff to Peppol access points.
EN 16931FacturX
Accounting
DATEV, SAP, Xero. Bidirectional.
Document flow, master-data sync, reversal logic and account mapping. No midnight CSV imports.
SKR03 · SKR04GoBD-compliant
Payments
SEPA, card, Bacs, iDEAL, Bizum.
One PSP layer instead of three. Mandates, pre-notifications, chargeback workflows and a retry plan that knows when banks are open.
StripeAdyenMollie
Pricing
Volume tiers, packages and formulas from one engine.
Volume, graduated, or package, with formulas if needed, modeled once, not stitched across three tools.
rate_expressionPriceFormula
Dunning
Collections that do more than send emails.
A real dunning state machine with AI-timed retries and automatic SEPA R-transaction recovery.
per planper subscriptionper org
Data Model
An open schema, not a disguised ERP.
Subscriptions, usage events, invoices, credit notes, payments. Cleanly normalized, documented, fully API-describable.
REST · v2OpenAPI 3.1WebhooksSDKs: TS · Go · Python
02 · Platform
One platform. No patchwork.
Subscriptions, payments, taxes and accounting – what most EU teams assemble from three separate systems, Kontorion delivers as one integrated platform.
Compliance
EU tax logic that survives an audit
VAT OSS, reverse charge, VIES and XRechnung - out of the box, no add-ons.
- EU VAT OSS · automated quarterly filing
- Reverse charge §13b/§14 UStG native
- XRechnung today; ZUGFeRD from June 2026
Payments
Every EU payment method, without a second PSP contract
SEPA, cards, Apple/Google Pay and SCA - live today, no second contract needed.
- SEPA Direct Debit CORE + B2B (GoCardless)
- Cards + Apple/Google Pay + SCA (Stripe)
- R-transactions feed into dunning automatically
Contracts
Ramp-ups, promos and pauses, properly modelled
Six contract phases with mid-cycle proration and Preview mode.
- Trial · Intro · Standard · Ramp · Overlay · Promotion
- Mid-cycle proration included
- Plan migration with Preview mode
Pricing
Volume tiers, packages and groups from one engine
Three pricing models with formulas, overrides and keyed prices.
- VOLUME · STAIRCASE · PACKAGE
- Per-tier formulas (cost × 1.15 + 200)
- Customer price overrides + keyed prices
Audit-ready
FX and tax, frozen at invoice time
FX rate and tax rule frozen at invoice time - existing books never touched.
- Plan versioning (replay-safe)
- FX pinning: period_start · issue · segment
- Policy changes never touch existing books
For developers
A production-ready API from the first call
REST with RFC 9457, signed webhooks, cursor pagination and test clocks.
- SDKs: Python · Go · TypeScript
- Sandbox keys + test clocks
- EU-only hosting, GDPR-native
03 · Business Models
Your business model is probably already covered.
Twelve documented blueprints – from per-seat SaaS to marketplace settlement. Each one ships with the API calls to get you live in under an hour. Configure, don't rebuild.
API platform
Examples
OpenAITwilioStripe APIAnthropic
How it works
Pay-per-call with graduated discounts, real-time visibility
API building blocks
usage events · STAIRCASE · idempotent aggregators
Hybrid PaaS
Examples
VercelSupabaseRenderPlanetScale
How it works
Flat tier + usage overage above included allowances
API building blocks
plan allowances · rollover · allowance webhooks
Marketplace + payouts
Examples
EtsyShopify PaymentsUberDoorDash
How it works
Platform takes a fee, settles to sellers weekly
API building blocks
settlements · counterparty rules · withholding
Subscription box
Examples
HelloFreshBarkBoxDollar Shave Club
How it works
Fixed delivery, pause/skip, gift subscriptions
API building blocks
recurring schedules · scheduled changes · wallet credits
04 · Implementation
Four steps to automated billing.
From connection to production – typically live in under two weeks.
01
Connect Payment Providers
Stripe for cards and GoCardless for SEPA Direct Debit - live today, connected in minutes. Mollie as an additional PSP ships in Q2 2026.
02
Configure Products & Rules
Set up pricing models, tax logic, and invoice templates. Everything in one place, not across three different tools.
03
Billing Runs Automatically
Recurring billing, dunning, revenue recognition - Kontorion takes over. AI monitors anomalies and optimizes collection timing.
04
Scale Without Rebuilding
From your first customer to 10,000+ subscriptions. No architecture changes, no migrations. Kontorion scales with you.
05 · Testimonials
Honestly: this is where stock-photo logos would be.
We publish customer logos only when the finance team has signed off, not when the sales slide needs them.
«Kontorion is in Early Access with a small cohort of design partners. Once the first quarter-end closes have run on Kontorion, we will replace this block with real voices - no stock photos, no invented logos.»
K As of May 2026 · Kontorion · Early Access
In the meantime, do it the hard way: check the substance.
06 · Comparison
Why European teams switch.
Lago, Chargebee and Hyperline are solid products – but they weren't built for EU market requirements. You'll notice the first time you close an OSS quarter.
- Fully supported
- Partially supported
- Not supported
| Kontorion | Lago | Chargebee | Hyperline | |
|---|---|---|---|---|
| EU VAT (OSS, reverse charge, VIES) | Partially supported | Partially supported | ||
| SEPA Direct Debit (CORE + B2B) | ||||
| XRechnung (native, with Leitweg-ID) | ||||
| IFRS 15 / ASC 606 rev rec | Partially supported | |||
| Plan & price versioning (replay-safe) | Partially supported | Partially supported | ||
| Per-invoice FX pinning | ||||
| Volume discounts, graduated tiers & packages (with formulas) | Partially supported | Partially supported | Partially supported | |
| Wallets + holds + prepaid | Partially supported | |||
| Marketplace settlements | ||||
| AI dunning + R-transaction routing | ||||
| RFC 9457 errors + idempotent webhooks | Partially supported | Partially supported | Partially supported | |
| Test clocks + sandbox keys | Partially supported | Partially supported | ||
| German UI + support | ||||
| Managed Cloud (EU-only) | Partially supported |
As of April 2026. Based on publicly available documentation from each provider. ZUGFeRD, Factur-X, and PEPPOL ship in Kontorion from June 2026 and are therefore not listed as current features.
07 · Developers
An API that's actually fun.
Five calls from empty org to first invoice. One data model for finance, engineering, and ops.
- RFC 9457 errors
- Signed at-least-once webhooks
- Cursor pagination
- Test clocks in sandbox
- SDKs: Python · Go · TypeScript
- EU-only, GDPR-native
Where is my data stored?
In European data centers. Your data never leaves the EU. GDPR compliance is not an add-on, but a foundation of the architecture.
How long does migration from Stripe Billing or Chargebee take?
Most teams are fully migrated in under two weeks. We provide a migration tool and personal support throughout the switch.
Can I try Kontorion before committing?
Yes. 14 days free, no credit card required. You work with real data in a sandbox environment.
Which payment providers are supported?
Live today: Stripe (cards, Apple/Google Pay, SCA) and GoCardless (SEPA Direct Debit CORE and B2B). Mollie (iDEAL, Bancontact, SEPA) is planned for Q2 2026. More PSPs based on customer demand - tell us what you need.
How does AI dunning work?
Kontorion analyzes payment history and customer behavior to automatically send reminders at the right time through the right channel. No more manual follow-ups.
Is there an API?
A complete REST API with signed at-least-once webhooks, idempotency keys, cursor pagination, and RFC 9457 Problem Details for errors. SDKs for Python, Go, and TypeScript. Sandbox keys with test clocks. Documentation at docs.kontorion.eu.
Which business models does Kontorion handle?
Eleven blueprints in the docs - SaaS per-seat (Slack, Linear), API platforms (OpenAI, Twilio), hybrid PaaS (Vercel, Supabase), marketplaces (Etsy, Shopify), telco (T-Mobile, Vodafone), cloud (AWS, Hetzner), creator platforms, enterprise SaaS, reseller networks, subscription boxes, and outcome-based services. Each blueprint with concrete API calls running in under an hour.
How does replay-safe accounting work?
Plans, prices, and products are versioned. Every subscription pins to an immutable plan_version - catalog edits never silently mutate live invoices. Each invoice pins three FX candidates (period_start, issue, segment) and the tax rules at finalize. Migrations between versions are explicit, with PREVIEW mode.
Which pricing models are supported?
Three models per product: VOLUME (higher quantities unlock a lower rate retroactively), STAIRCASE (each tier pays its own rate), PACKAGE (bundles like SMS packs). Plus optional per-tier formulas (cost * 1.15 + 200), customer price overrides, and keyed prices for products with many SKUs (TLDs, regions).
09 · Contact
Sounds interesting?
Whether a short demo, technical questions, or a conversation about your billing requirements in the EU market – we're available.
contact@frontieralgorithmics.com
Aichach, Germany