Flatpay website screenshot

Flatpay

Flatpay is a Copenhagen-headquartered payments company founded in 2022 that sells card acceptance to small and medium-sized European merchants on a single flat per-transaction rate with no monthly subscription. Its product line is a PAX card terminal, an all-in-one point-of-sale system, an online payment solution for webshops built on the Frisbii (Billwerk+) platform, and Flatpay Capital merchant financing. The company operates in Denmark, Finland, Germany, Italy, France, the Netherlands and the United Kingdom, serves roughly 70,000 merchants, and reached unicorn valuation in 2025. Flatpay publishes no public developer portal, API reference or machine-readable specification: webshop integration is delivered through Frisbii+ Pay plugins and a merchant-issued API key for the Frisbii gateway, which is operated by a different company.

Flatpay is profiled on the APIs.io network. Tagged areas include Company, Payments, Point-of-Sale, Payment Terminals, and Merchant Acquiring.

Flatpay’s developer surface includes support, engineering blog, pricing, and 17 more developer resources.

24.4/100 emerging ▬ flat Agent 3/100 human only Front door AI 1/6 silent saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →
AccessFreemium
0 APIs
CompanyPaymentsPoint-of-SalePayment TerminalsMerchant AcquiringFintechOnline PaymentsDenmarkEuropeSmall Business

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0
Regulatory Posture applies to this provider. Its tags matched the Payments regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.
Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.
The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.
Show this score on your site. Kin Score badge preview for Flatpay It updates itself when the score changes. Paste this where you link to your API docs:
<a href="https://apis.io/providers/flatpay/"><img src="https://apis.io/badge/flatpay/card.svg" alt="Flatpay on APIs.io — Kin Score by API Evangelist"></a>
Other styles, a README pill and a shields.io endpoint are on the badge page.
Raise your score.
Agent readiness — checks not met, largest first (exact, from this profile):
  • Machine-Readable Contract +18 pts — api_specs includes an OpenAPI document
  • MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
  • Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
  • Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
  • Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
  • Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
12 more unmet checks in the Agent Readiness table above.
Kin Score — facets with the most composite points still available (weight × headroom):
Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/flatpay/apis.yml: open an issue on github.com/api-evangelist/flatpay to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Flatpay API pricing

Prices published by Flatpay. A free plan or tier is listed.

PlanPrice
Payment Terminal Free
Payment Terminal (above 200,000 EUR turnover) —
Basic POS EUR 1495
Premium POS EUR 2495

Plan details, limits and sources →

Pricing Plans 1

Published pricing tiers and plan structures.

Flatpay Plans Pricing

4 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Flatpay Rate Limits

0 limits

RATE LIMITS

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Flatpay Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Flatpay Vulnerability Disclosure

security.txt · contact published

SECURITY

Resources

Get Started 1

Portal, sign-up, and the first successful call

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

Design & Contract 1

Pagination, idempotency, versioning, errors, and events

Build 2

SDKs, sample code, and the tooling you integrate with

Access & Security 4

Authentication, authorization, and security posture

Operate 4

Status, limits, changes, and where to get help

Commercial 4

Pricing, plans, and the legal terms of use

Company 2

The organization behind the API

Source (apis.yml)

apis.yml Raw ↑
aid: flatpay
name: Flatpay
description: 'Flatpay is a Copenhagen-headquartered payments company founded in 2022 that sells card acceptance to small and
  medium-sized European merchants on a single flat per-transaction rate with no monthly subscription. Its product line is
  a PAX card terminal, an all-in-one point-of-sale system, an online payment solution for webshops built on the Frisbii (Billwerk+)
  platform, and Flatpay Capital merchant financing. The company operates in Denmark, Finland, Germany, Italy, France, the
  Netherlands and the United Kingdom, serves roughly 70,000 merchants, and reached unicorn valuation in 2025. Flatpay publishes
  no public developer portal, API reference or machine-readable specification: webshop integration is delivered through Frisbii+
  Pay plugins and a merchant-issued API key for the Frisbii gateway, which is operated by a different company.'
url: https://raw.githubusercontent.com/api-evangelist/flatpay/refs/heads/main/apis.yml
x-type: company
x-source: harvest:secondary-market
x-tier: stub
x-tier-reason: harvest
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  probe_state: none
  source:
  - plans
  - rate-limits
  - security
  generated: '2026-11-06'
  method: derived
specificationVersion: '0.23'
created: '2026-08-16'
modified: '2026-08-16'
image: https://cdn.prod.website-files.com/675c2b1d9cefa24db1fdcafc/681a7a4079e0bf9e26fad636_en-open-graph-main-all-products.jpg
tags:
- Company
- Payments
- Point-of-Sale
- Payment Terminals
- Merchant Acquiring
- Fintech
- Online Payments
- Denmark
- Europe
- Small Business
tags_raw:
- Company
- Payments
- Point of Sale
- Card Terminals
- Merchant Acquiring
- Fintech
- Online Payments
- Denmark
- Europe
- Small Business
apis: []
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://www.flatpay.com/
- type: Support
  url: https://www.flatpay.com/support
- type: HelpCenter
  url: https://help.flatpay.com/en/support/solutions
- type: Blog
  url: https://www.flatpay.com/blog
- type: Pricing
  url: https://www.flatpay.com/pricing
- type: Login
  url: https://portal.flatpay.com/
- type: TermsOfService
  url: https://www.flatpay.com/legal/terms-conditions
- type: PrivacyPolicy
  url: https://www.flatpay.com/legal/privacy-policy
- type: GitHubOrganization
  url: https://github.com/FLATPAY-DK
- type: StatusPage
  url: https://status.flatpay.com/
- type: Security
  url: https://flatpay.com/responsible-disclosure
- type: SecurityTxt
  url: well-known/flatpay-security.txt
- type: WellKnown
  url: well-known/flatpay-well-known.yml
- type: VulnerabilityDisclosure
  url: security/flatpay-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/flatpay-domain-security.yml
- type: LLMsTxt
  url: llms/flatpay-llms.txt
- type: Lifecycle
  url: lifecycle/flatpay-lifecycle.yml
- type: Plans
  url: plans/flatpay-plans-pricing.yml
- type: RateLimits
  url: rate-limits/flatpay-rate-limits.yml
- type: Packages
  url: packages/flatpay-packages.yml
x-enrichment:
  date: '2026-08-16'
  status: minimal
  artifacts_added: 9
  pass: local-v1
x-coverage:
  state: none
  reason: no-developer-program
  detail: Flatpay ships no developer program of its own — api.flatpay.com and developer.flatpay.com do not resolve, the 1,554-URL
    sitemap contains no /developers, /docs or /api path, and the help center's webshop-integration articles hand merchants
    an emailed API key and link out to Frisbii's billwerk.plus plugin pages, because Flatpay Online runs on the Frisbii (Billwerk+)
    platform operated by a different company.
  evidence:
  - url: https://api.flatpay.com/
    status: 0
  - url: https://www.flatpay.com/openapi.json
    status: 404
  - url: https://www.flatpay.com/sitemap.xml
    status: 200
  - url: https://help.flatpay.com/en/support/solutions
    status: 200
  - url: https://www.flatpay.com/.well-known/security.txt
    status: 200
  - url: https://www.flatpay.com/llms.txt
    status: 200
  checked: '2026-08-16'

Flatpay API — frequently asked questions

How much does the Flatpay API cost?

Flatpay publishes its prices; its Basic POS plan is EUR 1495 as of 2026-08-16. APIs.io lists 4 pricing plans for Flatpay, with each plan's price, limits and inclusions under Pricing on this page.

Is the Flatpay API ready for AI agents?

Flatpay has a Kin Score of 24.4 out of 100 (emerging) and an Agent Readiness score of 2.5 (human-only), scored by API Evangelist on 2026-11-06.

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