Observed Signal · Aug 10, 2026 · M&A - Announced · Source: Trending Topics · Impact: 2/5 · Sentiment: Positive
Infrastructure Market: Callstack Acquires Margelo for Over $20M
Polish software company Callstack is acquiring Vienna-based engineering firm Margelo in a deal valuing the latter at more than €20 million. Both companies specialize in React Native, a cross-platform framework for building mobile apps. Margelo is known for its open-source libraries (VisionCamera, react-native-mmkv, Nitro Modules) and contract development for clients like Discord, Coinbase, and Expensify. Callstack, founded in 2016, employs over 200 people and serves enterprise clients. The acquisition aims to expand Callstack's technology portfolio and support international growth. Founder Marc Rousavy will stay on and retain a significant stake. The deal follows a recent growth investment from Viking Global Investors that valued Callstack at around €120 million.
M&A in the React Native development ecosystem; relevant to mobile app development and MarTech tooling for brands.
Key Takeaways & Evidence Grounding
- Callstack is acquiring Margelo for a valuation exceeding €20 million.
- Margelo is known for open-source React Native libraries with over 420 million total npm downloads.
- Marc Rousavy will remain with the combined company as a significant shareholder.
- Callstack was valued at roughly €120 million after a 2025 investment from Viking Global Investors.
- The acquisition is intended to broaden Callstack’s React Native technology and open-source portfolio.
Connected Companies & Entities
4 Entities mappedMeta
Consumer internet platforms monetised through advertising, apps, subscriptions and VR.
Viking Global
Global investment firm managing public, private, credit and structured-capital strategies.
“US fund Viking Global Investors came in with a growth investment that valued Callstack at roughly half a billion zloty (about 120 million eu...”
Margelo
React Native mobile engineering and product design agency.
“Polish software company Callstack is acquiring Vienna-based engineering firm Margelo....”
Callstack
Enterprise React Native engineering and AI delivery services.
“Polish software company Callstack is acquiring Vienna-based engineering firm Margelo....”
Ontology Mapping & Concepts
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