DATEV Unternehmen Online API Integration
Maesn is the only Unified API officially certified by DATEV, that enables you broad access to DATEV Unternehmen Online and DATEV Rechnungswesen with two-way-sync capabilities.
DATEV Unternehmen Online is a cloud-based collaboration platform by DATEV that connects businesses with their tax advisors.
DATEV Interface Partner
Have a Certified DATEV
Integration in Hours
Certified & Compliant
Get a DATEV certified integration via Maesn. Our API is continuously tested, secured and maintained.
Post & Pull data
Post and Pull data via our REST API and forget about CSV/XML and services.
DATEV Sandboxes
We provide DATEV sandboxes, enabling you to fully focus on you product.
REST API only
Forget about XML, CSV, and special DATEV formats. You only work with an easy REST API.
DATEV integration in days: How Rally (YC25) launched faster with Maesn
Rally is a financial platform for businesses that operate vehicle fleets.
"Maesn transformed the way how to integrate with DATEV. What would have been a complex long process turned into a smooth, intuitive process thanks to their REST API, DATEV sandbox and certification process. There are simply just upsides."
Thiago Peres
CTO @ getrally.com
One API for your DATEV Unternehmen Online integration use cases.
Unified. Certified. Production-ready.
Post invoices, bills and credit notes directly into DATEV Unternehmen Online.
Push structured invoice, bill, and credit note data — including attachments — directly into your users' DATEV Unternehmen Online environment. No manual uploads, no format conversion, no back-and-forth with the tax advisor.
Invoices, bills & credit notes with attachments
Structured data in the correct DATEV format
Direct posting into the user's DATEV environment
No DATEV formats. Just a clean REST API.
Forget about XML, CSV, DATEV-specific formats — maesn handles all the conversion in the background. You work with a straightforward REST API and maesn takes care of the rest.
No XML, CSV or DATEV-specific formats
Simple REST API — one standard for all systems
Format conversion handled by maesn
Secure multi-company support for DATEV Unternehmen Online.
Multi-company support out of the box — every DATEV Unternehmen Online integration is strictly isolated and enterprise-grade secure.
Strict environment isolation per company
Enterprise-grade security & compliance
Built for multi-tenant SaaS products
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DATEV authentication — handled like every other system.
Whether your users authenticate via SmartCard or SmartLogin — maesn abstracts the full DATEV auth flow behind the same unified interface you already know. No special handling, no extra implementation.
SmartCard & SmartLogin supported
Same auth interface as every other system
No DATEV-specific implementation required
Everything you can build with DATEV via Maesn.
From capturing invoices in DATEV Unternehmen Online to posting bookings and managing contacts in DATEV Rechnungswesen — Maesn covers the full range of DATEV workflows through one unified API. Including beta access to retrieve data directly from DATEV Rechnungswesen.
Capture invoices & bills in DATEV Unternehmen Online
Create bookings & contacts in DATEV Rechnungswesen
Retrieve data from DATEV Rechnungswesen
Get listed in the DATEV Marketplace — supported by maesn.
A DATEV Marketplace listing requires > 25 active connections, customer interviews and a strategic fit with DATEV. Maesn supports you through the entire process and your integration via Maesn counts exactly the same as a direct integration.
Marketplace listing fully supported via Maesn
Evaluation by DATEV partner team
Maesn guides you through the qualification process
DATEV is a collection of systems, modules and webservices.
Maesn covers them all.
DATEV consists of multiple systems, modules, and web services — each with its own formats and protocols.
Maesn abstracts all of it into one unified REST API, so you never have to deal with XML, CSV, or DATEV-specific formats directly.
Document Uploads
Belegbilderservice
Upload of bills, invoices or credit notes as PDF or JPG into DATEV.
Post Structured Data
Rechnungs-datenservice 1.0
Post structured data related to invoices, bills and credit notes
Post Journal entries
Buchungs-datenservice
Post reconciled journal entries to the accounting system.
Pull Journal Entries
Export Rechnungswesen
Pull journal entries with related data directly out of DATEV Rechnungswesen.
Whitepaper Learn everything about DATEV
Understand the difference between Unternehmen Online and Rechnungswesen, how specific use cases map to required webservices, how service activation works, and which data formats matter - and why none of this complexity matters when you use Maesn.
Get officially certified DATEV
integration via Maesn
Stop struggling with your own CSV/XML/DATEV APIs – Get a certified
DATEV integration with Maesn’s whitelabel process in days.
3 Reasons why it is better to integrate DATEV API with Maesn
Save months of effort
No need to understand DATEV complexity yourself — Maesn removes months of learning and implementation effort.
Save thousands of euros
Avoid costly clarification rounds, external support, and repeated coordination before going live.
Work with a proven partner
Maesn powers DATEV integrations trusted by thousands of companies — we know what works.
Read more in our related blog articles.
Everything you need to know about Datev Unternehmen Online
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Frequently asked
questions
You have more questions? We are looking forward hearing from you - book a meeting now!
What is DATEV Unternehmen Online?
DATEV Unternehmen Online is a cloud-based collaboration platform by DATEV that connects businesses with their tax advisors for shared access to invoices, bills, and financial documents — widely used across Germany.
What is the difference between DATEV Unternehmen Online and DATEV Rechnungswesen?
DATEV Unternehmen Online is used by businesses to upload and share financial documents with their tax advisor. DATEV Rechnungswesen is the accounting system used by the tax advisor themselves or by companies doing their own bookkeeping to process and book those documents. maesn supports both — through one unified API.
How do I integrate DATEV Unternehmen Online via Maesn?
Maesn provides a unified REST API that abstracts the full DATEV Unternehmen Online integration — including authentication, document uploads, and structured data posting. No XML, no DATEV-specific formats, no special handling required.
How do I get a DATEV sandbox for development?
Maesn provides all customers with a ready-to-use test environment for both DATEV Unternehmen Online and DATEV Rechnungswesen — so you can start building immediately without any dependencies.
Can I get listed in the DATEV Marketplace through Maesn?
Yes, an integration via maesn counts the same as a direct integration for DATEV Marketplace qualification. maesn supports you through the full process, including the 25-connection requirement and strategic fit evaluation.
Is it possible to pull data from DATEV?
Yes, via Maesn. DATEV Rechnungswesen data retrieval is available, allowing you to pull journal entries and related data directly out of DATEV through Maesn's unified API.
How do I activate DATEV web services like Belegbilderservice or Buchungsdatenservice?
DATEV web services are activated through the user's tax advisor directly in their DATEV instance. Once activated, maesn handles the full integration — your users simply authenticate and you're ready to go.
We are European.
Enterprise-grade security & compliance are our foundation.
Built and hosted in Germany to meet the highest security and compliance standards, Maesn processes API calls in real time without storing customer data and is fully ISO 27001 & GDPR compliant.
