Summary: Inside Nexus – The API Powering GeroWallet
In this edition of the Developers Office Hour, representatives from A.D. Labs present Nexus, the multi-chain data and transactional API infrastructure that powers GeroWallet. The presentation outlines why the team rebuilt their backend architecture around a WebSocket push model instead of traditional HTTP polling, while detailing Nexus’s feature suite across multiple blockchains.
Why Push Replaces Polling Traditional DApp and wallet backends rely heavily on REST API polling, which generates substantial network costs and operational overhead. Case studies conducted by the team demonstrated that up to 80% or more of traditional polling queries return empty responses, wasting API calls and increasing server costs by 3x to 11x. By transitioning to a WebSocket-based push model, Nexus streams live on-chain events directly to clients, reducing monthly requests for high-volume protocols from millions to just a few thousand targeted messages.
Core Product Suite and Yaci Engine Nexus currently supports three primary blockchains: Cardano, Bitcoin, and Midnight. The platform offers a multi-chain product set that includes:
- Blockchain API & Transaction Builder: High-speed data endpoints and unsigned CBOR transaction generation.
- WebSocket Event Streaming: Real-time event subscription channels.
- DEX Aggregator & Market Data: Route optimization across multiple decentralized exchanges and real-time asset pricing backed by a dedicated PostgreSQL database.
- MCP Server for AI Agents: Model Context Protocol integration enabling autonomous AI agents to query multi-chain data seamlessly.
Nexus’s core indexing engine is powered by the Java-based Yaci store framework. The team selected Yaci for its superior processing speed and actively contributes production fixes and pull requests back to the upstream repository.
Blueprints in Practice and Developer Tools Through the Nexus dashboard, developers can define “Blueprints”—customized WebSocket event filters that subscribe to specific on-chain criteria such as policy IDs, script hashes, staking credentials, or wallet addresses. Once configured, the server pushes relevant transactions in real time with zero empty response overhead. The dashboard also includes API key management, an interactive testing playground, and an embeddable swap widget for DApps.
Block Delivery Latency and Roadmap Benchmark testing demonstrates that Nexus delivers newly minted blocks with a median head start of approximately 2 seconds compared to traditional Blockfrost endpoints. Median request latencies sit at 4 to 5 milliseconds, with 99th percentile response times remaining under 800 milliseconds. Moving forward, the team’s roadmap includes extending support to EVM chains and Solana, developing cross-chain translation layers for enterprise onboarding, and coordinating with future Cardano protocol upgrades such as Ouroboros Leios.
Top Five Q&A (FAQ) about Nexus
Question 1: What is Nexus and what primary problem does it solve for Cardano applications? Answer: Nexus is a multi-chain data, streaming, and transaction API developed by A.D. Labs. It eliminates the inefficiency and high infrastructure costs of REST API polling by streaming on-chain events via WebSockets, reducing empty API calls by over 80%.
Question 2: Which blockchains are supported by Nexus? Answer: Nexus natively supports Cardano, Bitcoin, and Midnight, with planned future expansion to EVM chains and Solana.
Question 3: How do “Blueprints” work in the Nexus architecture? Answer: Blueprints allow developers to create targeted WebSocket subscriptions based on specific criteria like policy IDs, script hashes, staking credentials, or addresses. Whenever a matching transaction occurs on-chain, Nexus instantly pushes the payload to the subscriber without requiring repetitive polling.
Question 4: Why did the team select Yaci as the underlying indexing engine? Answer: The team chose Yaci because its Java-based architecture provides significantly faster indexing and query execution compared to traditional alternative providers. The team actively tests Yaci in production and submits performance fixes back to the open-source project.
Question 5: What latency advantages does Nexus offer compared to traditional RPC providers? Answer: Benchmark comparisons show that Nexus delivers new blocks to clients with a median head start of roughly 2 seconds over Blockfrost, achieving median response times of 4 to 5 milliseconds.
Friday, 16 October 2026
14:00 UTC
Developers Office Hours #83 | AddEvent