Sovereign & Open-Source
Subscription Engine
Subkit is the privacy-first, developer-friendly, self-hosted alternative to US-based proprietary platforms like RevenueCat and Adapty. Built to give developers full digital sovereignty.
Why We Are Building Subkit
In-app subscriptions have become the lifeblood of modern mobile and web applications. However, the ecosystem is heavily consolidated under US proprietary SaaS giants like RevenueCat and Adapty.
Every time a user subscribes, sensitive purchase receipts, customer journeys, and transaction values are routed through black-box architectures outside Europe. We believe that critical transaction pipelines must be transparent, secure, and fully owned by the developers building them.
Our mission is simple: to democratize in-app monetization by building an open-source standard for mobile subscriptions.
EU Digital Sovereignty & Grant Vision
Subkit is built directly in line with the European Commission’s Next Generation Internet (NGI) initiative. We champion an internet that is:
- ✓Human-Centric: Privacy by design, placing absolute control back in the hands of creators and consumers.
- ✓Open-Source Centered: Transparent codebases that prevent single-vendor monopolies and tech colonization.
- ✓Decentralized & Resilient: Self-hostable models enabling businesses to maintain data residency inside EU boundaries.
Our Core Pillars
Designed around trust, agility, and performance.
No Data Vendor Lock-in
Your transactional and user activity data resides entirely inside your own servers. Migrating or integrating with custom internal business tools is a simple database query away.
Auditability & Transparency
Proprietary SDKs act as black boxes where developers cannot verify background tracking or telemetry. Subkit is completely transparent and open for third-party security audits.
GDPR Compliance by Design
Run inside European cloud providers or fully on-premise infrastructure. By self-hosting Subkit, you guarantee 100% data residency compliance for EU users without complex compliance legal overlays.
Green IT & Performance
Unlike bloated proprietary SDKs that increase app size and battery consumption, Subkit’s zero-dependency native SDKs are ultra-lightweight. This preserves device battery, reduces data overhead, and minimizes carbon footprints—fully aligning with Green IT standards.
Open Core & Federation
We are not just building a self-hosted server. Our vision includes a federated model where distinct Subkit instances can securely communicate via verified APIs, establishing a decentralized subscription validation network that eliminates central monopoly points.
Zero-Dependency SDKs
Fully open-source client SDKs integrated directly within native frameworks like iOS Swift, Android Kotlin, Flutter, and React Native. Highly optimized to execute without impacting app boot performance.
Modern, Light, and Developer-Centric
How Subkit replaces heavy proprietary SDK configurations.
Self-Hosted Docker Node
Deploy the Subkit engine via a single Docker container. Connect to standard PostgreSQL or SQLite databases and scale horizontally as your traffic grows.
Zero-Dependency SDKs
Native iOS, Android, Flutter, and React Native client SDKs. Lean codebases that don't bloat your app sizes or slow down startup cycles.
SUPPORT THE INITIATIVE
Join us on GitHub and help us construct a sovereign digital future.
Let's Build a More Open Internet
Are you applying for NGI grants or looking to collaborate? We would love to share resources, documentation, and technical alignment.