Observed Signal · Jul 6, 2026 · M&A - Announced · Source: Trending Topics · Impact: 1/5 · Sentiment: Neutral
M&A Market: Callstack Acquires Vienna React Native Firm Margelo for Over €20M
Polish software specialist Callstack has announced the acquisition of Vienna-based engineering company Margelo at a valuation exceeding €20 million. Both firms specialize in React Native, a cross-platform framework for building iOS and Android apps from a shared codebase. Margelo is known for open-source libraries such as VisionCamera, Nitro Modules, and react-native-mmkv, and reports more than 420 million npm downloads. It counts Discord, Coinbase, Expensify, and VSCO among its clients and employs around 39 senior developers. Founder Marc Rousavy will remain on board and continue to develop Margelo's libraries. Callstack, founded in Wrocław in 2016, employs over 200 people and serves more than 100 enterprise clients. The acquisition follows a growth investment by Viking Global Investors in summer 2025 that valued Callstack at roughly €120 million. The companies cite AI-driven changes in software development as a rationale, shifting value toward architecture and performance. No closing date or regulatory approvals were disclosed.
Minor M&A in mobile engineering services; no direct advertising technology implications.
Key Takeaways & Evidence Grounding
- Callstack is acquiring Vienna-based Margelo at a valuation exceeding €20 million.
- Margelo's open-source libraries have accumulated over 420 million npm downloads, including VisionCamera, Nitro Modules, and react-native-mmkv.
- Margelo founder Marc Rousavy will remain on board as a shareholder.
- Viking Global Investors invested in Callstack in summer 2025, valuing the company at approximately €120 million.
- No closing date or regulatory approval details have been disclosed.
Connected Companies & Entities
8 Entities mappedMeta
Consumer internet platforms monetised through advertising, apps, subscriptions and VR.
“Callstack was founded a few months after the release of React Native by Meta....”
VSCO
Photography platform combining editing, business software, creator hiring and advertising.
“Margelo lists VSCO among its client references....”
Viking Global
Global investment firm managing public, private, credit and structured-capital strategies.
“US fund Viking Global Investors made a growth investment in Callstack in summer 2025....”
Coinbase
Digital asset exchange, custody and crypto infrastructure platform.
“Margelo lists Coinbase among its client references....”
Expensify
Expense, spend, card and travel management software for businesses.
“Margelo lists Expensify among its client references....”
Margelo
React Native mobile engineering and product design agency.
“Vienna-based Margelo is known for its React Native open-source libraries and counts Discord, Coinbase, Expensify, and VSCO among its clients...”
Discord
Community chat platform with subscriptions, digital goods and native ads.
“Margelo lists Discord among its client references....”
Callstack
Enterprise React Native engineering and AI delivery services.
“Polish software specialist Callstack is acquiring Vienna-based engineering company Margelo....”
Ontology Mapping & Concepts
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