The Settlement
Layer For
Gasless DeFi
VelumX is the gas abstraction protocol for Stacks (Bitcoin L2). Bridge, swap, and transact using only USDCx — no STX required at any step.
How It Works
Four steps from intent to Bitcoin-anchored settlement — no STX required.
User Signs Intent
The user signs a gasless transaction intent with their Stacks wallet, specifying the action and authorizing a USDCx fee.
Relayer Picks Up
The VelumX Relayer detects the signed intent and prepares a sponsored transaction, covering the required STX gas fee.
Paymaster Sponsors Gas
The on-chain Paymaster contract validates the USDCx authorization and reimburses the Relayer for the STX gas spent.
Settles on Bitcoin
The transaction is confirmed on Stacks and anchored to Bitcoin, giving the user Bitcoin-grade finality with zero STX held.
Core Capabilities
Everything you need to build and use gasless DeFi on Bitcoin L2.
Gasless Bridging
Bridge USDC from Ethereum to Stacks without holding STX. Fees deducted from your USDCx balance automatically.
Gasless Swaps
Swap tokens on the VelumX AMM paying fees in the input token. No STX required at any step.
Gasless Withdrawals
Send funds back to Ethereum without needing STX dust for the bridge fee. Pure stablecoin UX.
Intent Settlement
Sign a typed intent off-chain. The Relayer executes and the Paymaster settles — sub-block finality.
Universal SDK
React, Node, and Mobile SDKs. Integrate gasless transactions in under 20 lines of code.
Bitcoin-Native Finality
Every transaction anchors to Bitcoin via Stacks Nakamoto. Immutable, censorship-resistant settlement.
Built For Everyone
Whether you're a first-time DeFi user or a seasoned protocol builder, VelumX removes the gas barrier.
New User Onboarding
A user bridges USDC from Ethereum and immediately starts swapping on Stacks — no STX purchase required. VelumX removes the single biggest barrier to Bitcoin L2 adoption.
dApp Developer Integration
Add gasless UX to your Stacks dApp in an afternoon. The VelumX SDK handles intent signing, relayer communication, and fee abstraction so you can focus on your product.
DeFi Protocol Optimization
Reduce user drop-off at the gas step. Protocols integrating VelumX see higher conversion rates because users never leave the flow to acquire gas tokens.
Ecosystem & Integrations
Built on the most trusted infrastructure in the Bitcoin ecosystem.
Build Gasless Apps
Integrate in minutes. The VelumX SDK handles everything from intent signing to settlement.
import { VelumXClient } from '@velumx/sdk';const client = new VelumXClient({ network: 'mainnet', paymasterContract: 'SP...velumx-paymaster-v1',});// Gasless swap — user pays in USDCx, no STX neededconst result = await client.sponsoredSwap({ tokenIn: 'usdcx', tokenOut: 'stx', amount: 1_000_000, // 1 USDCx (6 decimals) slippage: 0.5,});console.log('Settled:', result.txId);React
Drop-in hooks for gasless transactions in any React or Next.js app.
Node.js
Server-side SDK for relayer integration and backend transaction sponsorship.
Mobile
React Native compatible. Bring gasless DeFi to iOS and Android.
Frequently Asked Questions
Everything you need to know about VelumX.