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, Card Terminals, and Merchant Acquiring.

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

🌐 Visit website 📡 Source on GitHub

28.1/100 thin Agent 6/100 human only Full breakdown ↓
scored 2026-08-17 · rubric v0.11.0

0 APIs

CompanyPaymentsPoint of SaleCard TerminalsMerchant AcquiringFintechOnline PaymentsDenmarkEuropeSmall Business

Kin Score

Kin Score How this is scored →
scored 2026-08-17 · rubric v0.11.0

Composite quality — 28.1/100 · thin

Contract Quality 0.0 / 21

Developer Ergonomics 1.1 / 17

Commercial Clarity 13.0 / 17

Operational Transparency 3.5 / 11

Governance 0.0 / 10

Discoverability 5.8 / 9

Regulatory Posture 4.7 / 15

Agent readiness — 6/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 3 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

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.

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/.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/flatpay: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

Pricing Plans 1

Published pricing tiers and plan structures.

Flatpay Plans Pricing

4 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Get Started 1

Portal, sign-up, and the first successful call

Login

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

WellKnown

WellKnown

LLMsTxt

LLMsTxt

Design & Contract 1

Pagination, idempotency, versioning, errors, and events

Lifecycle

Lifecycle

Build 2

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Packages

Packages

Access & Security 4

Authentication, authorization, and security posture

Security

Security

SecurityTxt

SecurityTxt

VulnerabilityDisclosure

VulnerabilityDisclosure

DomainSecurity

DomainSecurity

Operate 4

Status, limits, changes, and where to get help

Support

HelpCenter

StatusPage

RateLimits

Commercial 4

Pricing, plans, and the legal terms of use

Pricing

TermsOfService

PrivacyPolicy

Plans

Company 2

The organization behind the API

Website

Website

Blog

Blog

Source (apis.yml)

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
specificationVersion: '0.20'
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
- 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'