Observed Signal · Jun 22, 2026 · M&A - Announced · Source: Trending Topics · Impact: 2/5 · Sentiment: Neutral
Callstack Acquires Margelo in €20M+ React Native Engineering Deal
Polish React Native specialist Callstack has acquired Vienna-based engineering firm Margelo at a valuation exceeding €20 million. Both companies focus on the cross-platform framework React Native, which enables apps for iOS and Android from a single codebase. Margelo is known for its open-source libraries such as VisionCamera, react-native-mmkv and Nitro Modules, with more than 420 million npm downloads in total. It also provides contract development and performance optimization, counting Discord, Coinbase, Expensify, MetaMask, Rainbow, VSCO and WalletConnect among its references. Founder Marc Rousavy will remain a shareholder and continue developing the libraries. Callstack, founded in 2016 in Wrocław, employs over 200 people and serves more than 100 enterprise clients. The deal follows a growth investment from Viking Global Investors in summer 2025 that valued Callstack at roughly €120 million. Both firms cite AI-driven, increasingly agentic software development as the rationale for combining their capabilities.
Mid-sized M&A consolidating React Native engineering services; highlights AI-agent-driven shifts in software development, with limited direct impact on the AdTech ecosystem.
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Key Takeaways & Evidence Grounding
- Callstack is acquiring Vienna-based Margelo at a valuation of more than €20 million.
- Margelo's React Native open-source libraries have surpassed 420 million npm downloads.
- Margelo was founded by Marc Rousavy and employs around 39 senior developers.
- Callstack employs more than 200 people and serves over 100 enterprise clients.
- Viking Global Investors invested in Callstack in summer 2025, valuing it at roughly €120 million.
Connected Companies & Entities
6 Entities mapped“Polish software specialist Callstack is acquiring Vienna-based engineering company Margelo....”
“Polish software specialist Callstack is acquiring Vienna-based engineering company Margelo....”
“As references, Margelo names Discord, Coinbase, Expensify, MetaMask, Rainbow, VSCO and WalletConnect....”
“As references, Margelo names Discord, Coinbase, Expensify, MetaMask, Rainbow, VSCO and WalletConnect....”
“As references, Margelo names Discord, Coinbase, Expensify, MetaMask, Rainbow, VSCO and WalletConnect....”
“As references, Margelo names Discord, Coinbase, Expensify, MetaMask, Rainbow, VSCO and WalletConnect....”
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