Consolidating global open-source leadership and performance-first engineering in React Native, the combination sets a new benchmark for capability-led M&A in the AI era.
Warsaw / Vienna – September 2026 - Zeema acted as the exclusive buy-side M&A advisor to Callstack, a global leader in React Native and cross-platform enterprise engineering, on its strategic combination with Margelo, the Vienna-based high-end engineering pioneer behind industry-standard open-source technologies including Nitro Modules, VisionCamera, and react-native-mmkv. The transaction values Margelo at more than EUR 20 million.
Following Callstack’s 2025 growth investment, this acquisition marks a major milestone in Callstack’s international expansion strategy. The transaction combines Callstack’s decade-long enterprise delivery track record and core framework stewardship with Margelo’s deep-tech, performance-first engineering DNA. Together, Margelo’s flagship libraries - Nitro Modules, VisionCamera, and react-native-mmkv - command over 142 million combined downloads on npm, representing one of the most widely adopted foundational technology stacks in modern mobile development.
Defining the Capability Premium in Digital Services.
As generative AI accelerates and commoditizes baseline code generation, enterprise demand is shifting rapidly from raw delivery capacity to senior architectural authority, low-level performance, and end-to-end outcome ownership. The combination creates the undisputed global authority in high-performance cross-platform software, enabling Fortune 500 and high-growth technology leaders to build, validate, and scale mission-critical applications with unprecedented execution certainty.
Margelo’s established open-source libraries will remain fully open source, with Founder Marc Rousavy continuing to lead their development and shape the combined group’s advanced technology offering.
"
This deal perfectly captures where M&A demand from top-tier, specialized technology services firms is moving. The Margelo acquisition demonstrates that Callstack’s focus is on the core drivers of the next-generation services model: high-end technical depth, defensibility against automation, and proven brand authority established through proprietary open-source contributions.
At Zeema, we are truly excited to be advising on transactions in this new era of IT services. It reinforces both our deep domain expertise and our intuition for market shifts – insights we look forward to bringing to future mandates in the sector.
"
Michał Przybylski, Managing Partner, Zeema