Nimbus

Nimbus turns crypto payments into a smooth, instant, and gasless experience. No fees, no waiting, no technical hassle—just fast transfers with Web3-level security and Web2-level simplicity.

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Nimbus: Secure, Gasless Crypto Payments on Starknet

Inspiration

The idea for Nimbus came from a major problem in crypto today: even the most “secure” wallets get hacked. Phishing scams, compromised private keys, malicious approvals—users constantly lose funds. Right now, people are stuck between two bad options:

  • Self-custody (high risk if you make a mistake)
  • Centralized exchanges (you don’t actually own your crypto)

We asked: Why isn’t there a middle ground?
What if we could combine blockchain security with Web2-level simplicity—and remove gas fees altogether?

When we discovered Starknet and gasless infrastructure providers, we realized we could build a vault-based payment system that is secure, fast, and effortless.

That’s how Nimbus was born.

What it does

Nimbus is a gasless, instant crypto payment system on Starknet that solves three major problems:

1. Zero Gas Fees

Users never pay gas. Nimbus handles all transaction costs using an internal ledger + gasless infrastructure.

2. Vault-Level Security

Our Cairo smart contract vault provides:

  • Owner-controlled authorization
  • Emergency freeze function
  • Hot wallet separation
  • Full on-chain audit trail

3. Instant Transfers

Transactions settle in 2–5 seconds via internal ledger—no waiting for blockchain confirmations. It feels like a Web2 payment app, powered by Starknet.

Key Features

  • Smart contract vault with owner controls
  • Instant balance updates
  • Freeze/unfreeze + hot wallet revocation
  • Gasless UX through integrated infrastructure
  • Clerk-based authentication
  • Real-time monitoring dashboard in Next.js

How we built it

Tech Stack

  • Smart Contracts: Cairo 2.11.4 (Starknet)
  • Frontend: Next.js 14, React, TypeScript, Tailwind
  • Auth: Clerk (gasless onboarding)
  • Blockchain: Starknet Sepolia testnet
  • Gasless Infra: ChipiPay gasless SDK
  • Deployment Tools: Starkli, Starknet Foundry (sncast)

Architecture

User → Auth → ChipiPay Gasless SDK → Starknet → Nimbus Vault Contract

The vault uses u256 (split into two u128 parts) for safe balance tracking within Cairo’s limitations.

Challenges We Faced

1. Lack of Mobile Support

No official Swift SDK or clear examples for Starknet mobile integration.
Solution: Built web-first with Next.js while designing a path for future mobile support.

2. RPC Version Mismatch

Different RPC providers support different API versions (0.7, 0.8, 0.9).
Solution: Mixed providers based on tool requirements.

3. Account Type Issues

Initial deployment used an Argent X wallet with guardian—signatures incompatible.
Solution: Created a clean OpenZeppelin account for consistent signing.

4. Tool Fragmentation

Starkli and sncast each did different things well.
Solution: Used sncast for account setup, starkli for deployment.

5. u256 Math in Cairo

No native u256 support forced manual split logic with borrow handling.

What We’re Proud Of

1. Fully Functional Cairo Vault Contract

  • Owner authorization
  • Hot wallet delegation
  • Emergency freeze
  • Event-based transparency
  • Safe u256 balance math
    Deployed to Sepolia

2. True Gasless Payments

Integrated chipi pay gasless infrastructure so users never see or pay gas.

3. High-Efficiency Internal Ledger

Batch updates reduce cost by ~95% compared to token transfers.

4. Security-First Architecture

Multiple layers of protection and transparency.

5. Full Documentation

Step-by-step guides for contracts, frontend, deployment, and gasless integration.

What We Learned

  • Advanced Cairo smart contract development
  • Proper event design and gas optimization
  • Importance of internal ledgers (used by Venmo, Coinbase, Binance)
  • Balancing UX vs decentralization in real-world products
  • Developer experience can make or break adoption

What’s Next

Short-Term (Q1 2025)

  • Build native iOS app in Swift
  • React Native support
  • Gasless mobile transactions
  • Biometric login & session keys

Medium-Term

  • Multi-token support (ETH, USDC, USDT)
  • Merchant tools (QR payments, PoS, invoices)
  • Remittance and content creator features
  • DeFi yield on idle balances

Long-Term

  • Mainnet launch with audits
  • Millions of users
  • Global compliance
  • DAO-governed infrastructure

The Vision

Nimbus is the bridge between Web2 simplicity and Web3 security.

Crypto adoption won’t happen by forcing users to understand blockchain.
It will happen when the blockchain becomes invisible.

With Nimbus, you get:

  • Web2-level ease of use
  • Blockchain-level security
  • Zero gas fees
  • Instant settlement
  • Full transparency

We’re not replacing self-custody—we’re enabling mass adoption.

Nimbus makes crypto usable for everyone.

Built with love on Starknet, powered by Nimbus, secured by Cairo smart contracts.

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