Bitcoin Apps Need Liquidity Beyond Bitcoin

How Avail Nexus solves cross-chain liquidity for Bitcoin apps. Live workshop with Avail and Citrea

On May 14, 2025, Avail and Citrea hosted this live workshop at X Spaces. The session brought together Mayur from Avail, who led the technical demo, and Yilmaz from Citrea ‘s DevRel team.

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You can watch it again here:

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The event addressed one of the most persistent problems in the Bitcoin app ecosystem: how decentralized applications built on Bitcoin rollups access liquidity that exists on other chains, without forcing users to go through a long and tedious bridging process.

The Problem: Fragmented Liquidity

When a developer builds an application on a Bitcoin Layer 2 like Citrea, the first ZK rollup on Bitcoin, they immediately face a structural problem. Its users have funds distributed across different chains: Arbitrum, Optimism, Base, and the Ethereum mainnet. Moving those funds to the application requires bridges, swap transactions, gas across multiple networks, and wallet approvals at every step.

As Mayur explained during the session, the usual approach forces developers to choose between two equally bad options: deploying multiple instances of their protocol across different chains, or integrating fragmented bridging tools that result in a broken user experience. Neither option scales. Both add maintenance complexity and divide communities.

Avail Nexus: The app receives LIQUIDITY, regardless of its origin | Multiple chains supported, N-to-1 provisioning, seamless UX integration

The Solution: Avail Nexus

Avail Nexus is a cross-chain liquidity unification layer designed precisely to solve this problem. Instead of forcing apps to manage multiple deployments or integrate unreliable bridges, Nexus enables Na-1 liquidity aggregation: a user’s assets from any supported chain can be routed directly to a target application in a single, transparent flow.

Key features of Avail Nexus:

• Multi-chain support: Compatible with a wide variety of EVM networks.

• N-to-1 Liquidity Provision: Aggregates balances from multiple chains into a unified position.

• Seamless UX integration: The Nexus SDK is embedded directly into the app’s frontend. The user never leaves the interface to bridge or swap.

• Developer-oriented: Minimal integration via TypeScript SDK and pre-built React components.

Mystic Earn on Citrea: “Earn on Bitcoin’s first zk rollup.” Demo app used during the workshop. $2M in total deposits.

Live Demo: Mystic Finance in Citrea

Mayur demonstrated a live, functional integration using Mystic Finance, a money market protocol deployed on Citrea. The use case was simple: a user wants to deposit ctUSD into Mystic Earn on Citrea, but their USDC balance is distributed among Arbitrum, Optimism, and Base.

Without Nexus, this would require bridging funds from each chain individually, acquiring gas tokens on each network, multiple wallet approvals and signature confirmations, and waiting for cross-chain transactions to complete.

In the demo, Nexus compresses all of this into a single deposit action. The SDK detected the user’s unified USDC balance across all chains, automatically constructed the necessary swaps and approvals, and executed the deposit on Mystic. All with a single transaction confirmation from the user.

Live code walkthrough: depositViaNextus function using the Avail Nexus SDK | swapAndExecute pattern in VS Code

Results: End-to-End in a Single Action

The live demo showed the deposit successfully completing on Citrea: $20 deposited into the Mystic vault, gas covered from the user’s existing cross-chain balances, and no manual bridging required. The Mystic Finance dashboard confirmed the position in real time.

Yilmaz from Citrea commented on the integration from the app developer’s perspective:

“User onboarding and retention are the main pain points. If you can’t onboard a user the first time, you lose them. This addresses both sides: you reach users where they already have their funds.”

Avail Nexus integration options: Nexus SDK (TypeScript) | UI Elements (React) | Nexus API (coming soon)

How to Get Started with Avail Nexus

There are three integration paths available for developers:

• Nexus SDK : Full programmatic control via headless SDK in TypeScript. Ideal for custom UX implementations.

• UI Elements : Pre-built React components for quick integration. Ready to use directly in production.

• Nexus API : Programmatic API access, coming soon.

For teams building on Citrea or any Bitcoin Layer 2 and needing their users to bring in liquidity from the broader EVM ecosystem, Avail Nexus provides a production-ready integration path with minimal overhead.

Our Perspective

The cross-chain liquidity problem is one of the most significant UX barriers in crypto. What Avail Nexus demonstrates is that the solution doesn’t have to be complex for developers. The complexity can be abstracted behind a clean SDK interface.

At Cumulo, we operate infrastructure across multiple ecosystems and have seen firsthand how liquidity fragmentation impacts protocol adoption. The work Avail and Citrea are doing together , bringing real-world, native BTC use cases to production while addressing asset accessibility, is a significant step toward a more composable and user-friendly ecosystem.

Validators and infrastructure providers like us exist precisely to support these types of projects: technically sound, community-oriented, and built for the long term.

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