Rechnungskit is the layer that was missing in our own shop.
Rechnungskit was built in the online shop of Happy Coffee. The way from order to payment to DATEV was the same every month, and every month it was manual work. Rechnungskit covers that way from the incoming payment onward instead of cleaning up afterwards.
Built out of necessity, not as a product idea.
Christian Häfner co-founded FastBill and built invoicing software for freelancers and small businesses. So he didn't spot the gap Rechnungskit closes as an outsider, but in a market he knows from the inside.
Even so, Rechnungskit started as a problem in his own business rather than a product idea. With Happy Coffee, Christian Häfner runs an online shop, and with it the same route every month: order, payment, document, bookkeeping, DATEV.
"There was no tool that covered the way from the shop through the payments to DATEV in one go," says Häfner. What the market offered started at the end of the chain: tools that clean up afterwards so the data fits DATEV.
Häfner's approach was the reverse: instead of sorting out what already went wrong, capture the process cleanly from the incoming payment onward. What came out of that for Happy Coffee has run in production there ever since. In July 2026 it became Rechnungskit, a product of its own for online shops with the same problem.
Who is behind Rechnungskit
Three decisions that explain everything else
Why Rechnungskit looks the way it does.
From our own business
Rechnungskit was built for our own shop before it became a product. It runs in real operations at Happy Coffee and has been through real tax audits.
From the payment, not after it
Rechnungskit starts at the incoming payment and creates the correct document instead of repairing bookings afterwards. Document, matching and DATEV handover are connected in one process.
Your data stays yours
Developed in Germany, hosted in Germany. Documents are archived tamper-proof and remain exportable. Details on the security page.
Integrations
Shop system and payment provider are both connected: Rechnungskit reads the order and the matching payment and creates the document from them. Details for each integration on the integration pages.
Shopify
WooCommerce
Shopware
Stripe Billing
Mollie
PayPal
Unzer
GoCardless
DATEV-Export"Doesn't this exist already?"
Parts of it, yes. A document passes through several steps (order, payment, document, matching, DATEV export, tax advisor), and there is good software for each of them. So what matters is not who covers how much, but where the seams are: every jump between two products is a point where data gets handed over, reconciled and, when in doubt, fixed by hand.
Rechnungskit covers this way from the incoming payment to the DATEV handover in one product. How that compares with other providers in detail is in our sourced comparisons, including the cases where the competitor is the better choice.
All comparisons with sourcesMaterial for coverage
Facts, boilerplate, logos and a founder portrait, cleared for editorial use. Everything from here on is for journalists.
Boilerplate in three lengths
Approved company description. Please use it unchanged; for shorter text, take the next shorter version.
Rechnungskit automates invoices and records for online shops: from incoming payment to the DATEV handover in one continuous process. A product of Happy Coffee GmbH.
Rechnungskit is invoicing and bookkeeping automation for online shops and SaaS companies. Instead of tidying up bookings for the accountants after the fact, Rechnungskit covers the whole way from the incoming payment: a compliant ZUGFeRD e-invoice, a GoBD archive and a DATEV export. The product was built in the online shop of Happy Coffee GmbH, where it runs in production every day. Rechnungskit is publicly available; every account starts in a free test mode.
Rechnungskit is invoicing and bookkeeping automation for online shops and SaaS companies. Most tools on the market sort transaction data for the accountants after the fact. Rechnungskit reverses the order: the process is captured cleanly from the moment a payment comes in. Every payment becomes a compliant ZUGFeRD e-invoice, archived tamper-proof under the GoBD and handed to DATEV as a finished booking batch. Rechnungskit was built in the online shop of Happy Coffee, one of Germany's leading D2C coffee brands, where the way from order to payment to bookkeeping used to be manual work across several tools every month. Rechnungskit runs in production at Happy Coffee every day and is publicly available; every account starts in a free test mode. Founder and managing director is Christian Häfner, who previously co-founded FastBill.
Logo & brand
Please use only these files. The wordmark is always "Rechnungskit" as one word, with no capital K in the middle.
- Leave enough clear space around the mark
- Brand colors: green #0F8C7E and ink #161A18
- Use the standard version on light backgrounds
- Distort, rotate or add shadows
- Use your own colors, gradients or outlines
- Spellings like "RechnungsKit" or "Rechnungs-Kit"
Live demo for journalists
Instead of screenshots, take a direct look at the product: a read-only demo with sample data, from incoming payment to DATEV export. You may use your own images from it editorially.
From the blog
The latest posts from rechnungskit.de/blog.
Rechnungskit is now available to everyone
The waitlist is history: online shops and SaaS providers now create their own account and start in the free test mode.
Rechnungskit opens its waitlist
The invoicing and bookkeeping automation that grew out of Happy Coffee's own online shop becomes a standalone product, starting as a private beta for a limited number of online shops.
All postsMilestones
Questions, an interview or material?
The founder answers requests himself, usually within one business day: support@rechnungskit.de