Frankfurt-based fintech startup Donnerstag.ai is tackling a critical blind spot in European supply chains with an AI-powered platform that brings transparency to accounts receivable management, addressing a €825 billion ecosystem where suppliers lose billions annually due to lack of visibility over deliveries, invoices, and payments.
What is Donnerstag.ai?
Donnerstag.ai is a German financial technology startup that provides an AI-powered accounts receivable management platform specifically designed for suppliers operating within self-billed invoice ecosystems. Founded in 2024 and headquartered in Frankfurt am Main, the company addresses a fundamental problem that has plagued European suppliers for decades: the opacity created by self-billed invoicing systems, known in Germany as “Gutschriften.”
The company’s name, “Donnerstag,” means “Thursday” in German, symbolising the day when suppliers traditionally receive their payment confirmations and reconcile accounts. This seemingly routine business moment is actually fraught with complexity, confusion, and potential revenue loss for hundreds of thousands of European suppliers.
In self-billed invoice systems, the enterprise buyer creates the invoice rather than the supplier. Whilst this arrangement works efficiently for large buyers who can automate their processes, it creates a black box for suppliers who lack visibility into what was invoiced, what was paid, when the next payment is coming, and whether there are discrepancies between what was delivered and what was billed. Suppliers often only discover problems when expected payments fail to arrive, by which time the opportunity to rectify issues has often passed.
Donnerstag.ai’s platform uses artificial intelligence to connect data from ERP systems, service recording platforms, and banking systems, detecting discrepancies in real time and automatically reconciling thousands of transactions. The intelligent algorithm identifies inconsistencies, predicts missing line items, and alerts finance teams before revenue is lost, transforming accounts receivable management from a reactive, manual process into a proactive, intelligent financial control layer.
The €825 Billion Problem: Understanding Self-Billed Invoicing in Germany
To appreciate Donnerstag.ai’s value proposition, it’s essential to understand the scale and nature of the self-billed invoicing challenge, particularly in the German market.
In Germany alone, over 580,000 suppliers operate within a €825 billion self-billed invoice ecosystem. This system is prevalent across industries including retail, manufacturing, logistics, and services, where large enterprise buyers prefer to control the invoicing process to facilitate their own automation and reconciliation.
The mechanics of self-billed invoicing create several critical pain points for suppliers:
- Lack of transparency: Suppliers cannot see what the buyer has invoiced until payment arrives (or doesn’t), creating weeks of uncertainty about accounts receivable status.
- Discrepancy detection delays: When delivered quantities don’t match invoiced amounts, or when pricing errors occur, suppliers often discover these issues too late to easily dispute or correct them.
- Manual reconciliation burden: Suppliers must manually match bank payments against delivery records and their own service documentation, a time-consuming process prone to errors, especially for suppliers serving multiple large buyers.
- Revenue leakage: The combination of opacity, delayed detection, and manual processes means suppliers lose billions annually through under-invoicing, missed deliveries, pricing errors, and uncollected receivables.
Enterprise buyers, meanwhile, have invested heavily in automation and ERP systems that handle self-billed invoicing efficiently. This asymmetry leaves suppliers at a significant disadvantage, particularly small and medium-sized enterprises (Mittelstand companies) that lack resources to build comparable systems.
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Donnerstag.ai Funding: €4.3 Million Seed Round Validates Market Need
In November 2025, Donnerstag.ai announced the completion of a €4.3 million seed funding round, a substantial seed investment that reflects strong investor confidence in both the founding team and the market opportunity.
The round was led by Speedinvest, one of Europe’s most active and respected early-stage venture capital firms, with participation from QED Investors, a leading fintech-focused VC firm, Crestone VC, and several prominent European business angels with experience in financial services and enterprise software.
The calibre of the investor syndicate is particularly noteworthy. Speedinvest has backed successful fintech companies including Bitpanda, wikifolio, and refurbed, demonstrating pattern recognition in identifying scalable fintech platforms. QED Investors, meanwhile, specialises in fintech and has invested in companies including Credit Karma, Nubank, Klarna, and SoFi, providing both capital and strategic guidance to fintech startups navigating complex markets.
Stefan Klestil, General Partner at Speedinvest, explained the firm’s investment thesis: “At a time when artificial intelligence is redefining ERP and financial systems, Donnerstag.ai is creating an entirely new category that has never been technologically addressed before. Barbaros and Volkan combine product expertise, strategic vision, and executional strength in a unique way. We’re proud to lead this round and work with Donnerstag.ai to shape the future of European financial technology.”
Donnerstag.ai Founders: Serial Fintech Entrepreneurs Returning to Product Development
Donnerstag.ai was co-founded by Barbaros Özbugutu and Volkan Özkan, two experienced fintech entrepreneurs with complementary backgrounds spanning payments, technology, and European markets.
Barbaros Özbugutu: CEO and Payment Industry Veteran
Barbaros Özbugutu serves as Co-Founder and CEO of Donnerstag.ai. He brings over 15 years of experience in the global payment and telecommunications sectors, with a track record that includes one of Turkey’s most successful fintech exits.
Özbugutu’s career began in the telecom sector at Telefónica Germany, where he served as Team Manager of the Business Service Center from 1999 to 2005. He then moved into financial services, joining Firstdata in 2005 before moving to Telecash, a Firstdata subsidiary, as Director responsible for the SME market in 2007.
In 2010, Özbugutu joined Klarna GmbH as Vice President of Sales Germany, where he worked until 2012. This role provided crucial insights into the European payment landscape and the challenges facing both merchants and financial service providers.
Most significantly, Özbugutu co-founded iyzico in 2013, an online payment services provider that democratised financial services in Turkey. As CEO, he led the company through rapid growth, securing Series B funding and attracting international investors including the International Finance Corporation, Speedinvest, Vostok Emerging Finance, 212 Capital, and Amadeus Capital Partners. The company raised $28 million and served over 1,000 marketplaces and 100,000 online merchants, including major brands like Amazon, Nike, and Zara.
In 2019, iyzico was acquired by global payment giant PayU (Prosus/Naspers) in what was reportedly one of the largest fintech acquisitions in Turkey. Özbugutu continued leading iyzico as Chairman and CEO of PayU Turkey until 2022.
After the successful exit, Özbugutu founded DeBa Group S.A. SPF, a family office, and DeBa Ventures, a firm dedicated to investing in early-stage tech startups. His experience as an investor, however, ultimately led him back to product development. “I was looking to transition from just supporting to building again,” Özbugutu explained. “The self-billed invoice problem in Germany represents exactly the kind of challenge that requires both technical innovation and deep understanding of financial operations.”
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Volkan Özkan: Co-Founder and Technical Architect
Volkan Özkan serves as Co-Founder of Donnerstag.ai, reuniting with his former iyzico colleague to tackle the accounts receivable challenge. Özkan brings extensive experience in fintech product development and a deep understanding of the technical complexities involved in financial data integration and reconciliation.
The co-founders’ shared history at iyzico, where they built a payment platform serving hundreds of thousands of merchants, provides crucial experience in handling high-volume financial transactions, integrating with diverse systems, and building products that work reliably in mission-critical financial contexts.
How Donnerstag.ai Works: AI-Powered Receivables Management
Donnerstag.ai’s platform is built around several core capabilities that work together to provide suppliers with unprecedented visibility and control over their accounts receivable.
Data Integration and Connectivity
The platform connects to multiple data sources within a supplier’s technology ecosystem:
- ERP systems: Integrates with enterprise resource planning platforms to access delivery records, pricing information, and customer data.
- Service recording systems: Pulls data on services rendered, quantities delivered, and contractual terms.
- Banking systems: Monitors incoming payments and automatically matches them against expected receivables.
This multi-source integration creates a comprehensive view of the entire order-to-cash cycle, from initial delivery through final payment.
Real-Time Discrepancy Detection
Once data is integrated, Donnerstag.ai’s AI algorithms analyse transactions continuously to identify discrepancies:
- Quantity mismatches: Detects when invoiced quantities don’t match delivery records.
- Pricing errors: Flags instances where the wrong price was applied or contractual discounts weren’t reflected.
- Missing line items: Predicts deliveries that should have been invoiced but weren’t included in the buyer’s self-billed invoice.
- Payment delays: Identifies overdue payments and patterns suggesting potential collection issues.
The system operates in near real-time, meaning discrepancies are flagged within hours or days rather than weeks or months, when intervention is still practical.
Intelligent Reconciliation
Perhaps the platform’s most valuable capability is automated reconciliation. Traditionally, suppliers must manually match bank deposits against delivery records and self-billed invoices, a tedious process that becomes exponentially more complex as transaction volumes increase.
Donnerstag.ai’s algorithms automatically reconcile thousands of transactions, learning from each customer’s unique data patterns to become increasingly precise over time. The system handles the complexity of partial payments, multi-line-item invoices, and the variations in how different buyers structure their self-billed invoices.
Proactive Alerts and Workflows
When issues are detected, Donnerstag.ai doesn’t simply generate reports. The platform alerts relevant finance team members via integrated workflows, providing specific information about the discrepancy and recommended actions. This transforms finance teams from reactive reconcilers into proactive revenue protectors.
Strategic Deployment of Seed Capital
The €4.3 million will be deployed across several strategic priorities designed to establish Donnerstag.ai as the leading accounts receivable platform for suppliers across the DACH region (Germany, Austria, Switzerland):
- Product development: Enhancing AI algorithms, expanding integration capabilities with additional ERP and banking systems, and building features requested by early customers.
- Market expansion: Scaling sales and marketing efforts across Germany, Austria, and Switzerland, targeting the hundreds of thousands of suppliers within the self-billed invoice ecosystem.
- Team growth: Hiring engineering talent, customer success specialists, and sales professionals to support rapid customer acquisition.
- Partnership development: Establishing relationships with ERP vendors, industry associations, and accounting firms to facilitate customer acquisition and product integration.
Market Opportunity and Competitive Landscape
The accounts receivable automation market in Europe is experiencing significant growth and investor interest. In 2025 alone, several noteworthy funding rounds have validated the market opportunity:
- Mimo (UK/Stockholm): Raised €7.7 million in a seed round to build a B2B payments and accounts receivable solution.
- Tapline (UK, serving DACH/CEE): Secured €20 million in equity and debt to pre-finance future receivables for B2B SaaS and subscription businesses.
- Factris (Netherlands/Lithuania): Raised €100 million in a facility to support invoice factoring services for SMEs across Europe.
Including Donnerstag.ai’s seed round, these funding announcements represent approximately €127.7 million in capital deployed to working capital and accounts receivable solutions in 2025 alone, highlighting significant investor appetite for platforms that help businesses optimise cash flow.
Donnerstag.ai occupies a unique position within this landscape. Whilst competitors like Tapline focus on receivables pre-financing and Factris provides invoice factoring, Donnerstag.ai addresses the specific challenge of supplier receivables management within self-billed ecosystems, a niche that has been largely overlooked by existing solutions.
Donnerstag.ai Key Takeaways
- Substantial Seed Funding for Niche Solution: Donnerstag.ai raised €4.3 million in November 2025 led by Speedinvest and QED Investors, validating the market need for AI-powered accounts receivable management specifically designed for suppliers operating within Europe’s €825 billion self-billed invoice ecosystem.
- Experienced Serial Entrepreneurs: Co-founders Barbaros Özbugutu and Volkan Özkan bring proven track records, including the successful iyzico exit to PayU/Prosus in 2019, combining payment industry expertise with product development capabilities to tackle a problem affecting 580,000+ German suppliers.
- AI-First Approach to Unsolved Problem: The platform creates a new software category by applying artificial intelligence to automate reconciliation of self-billed invoices, detecting discrepancies in real time and preventing revenue leakage, a problem that traditional ERP and accounting systems haven’t adequately addressed.
- Strategic DACH Market Focus: By targeting the German, Austrian, and Swiss markets where self-billed invoicing is particularly prevalent and where Mittelstand suppliers lack the resources to build internal solutions, Donnerstag.ai addresses a massive addressable market within Europe’s economic powerhouse region.
Conclusion: Levelling the Playing Field for European Suppliers
Donnerstag.ai represents a compelling case study in how experienced entrepreneurs can identify overlooked problems in established industries and apply modern technology to create substantial value. The self-billed invoicing challenge has existed for decades, costing suppliers billions annually, yet remained largely unaddressed by enterprise software vendors who focused primarily on buyer-side optimisation.
By combining deep fintech expertise with artificial intelligence and a laser focus on a specific, large-scale problem, Özbugutu and Özkan have positioned Donnerstag.ai to become the standard platform for supplier receivables management across the DACH region and potentially beyond.
The strong seed funding, led by respected fintech investors, provides the resources needed to rapidly scale customer acquisition, enhance the platform, and establish market leadership before competitors recognise the opportunity. For Europe’s hundreds of thousands of suppliers struggling with opacity in their accounts receivable, Donnerstag.ai offers the transparency, speed, and control that enterprise buyers have long enjoyed, finally levelling the playing field in European supply chains.
As CEO Barbaros Özbugutu noted: “Every year, suppliers lose billions because they lack transparency over what has been delivered, invoiced, and paid. With our AI-powered platform from Germany, we’re bringing clarity to a sector that is central to Europe’s competitiveness.” For investors, customers, and the broader fintech ecosystem, Donnerstag.ai’s emergence signals that even in mature markets, innovative technology combined with entrepreneurial execution can unlock substantial value by solving real, persistent problems.