Gasless USD₮0 Demo

This project demonstrates a gasless token-transfer flow on the Flare Network using a two-piece architecture:

1. Front-end (React + Ethers.js)

   • Presents a simple UI: a “recipient” field, an “amount” field, and a “Send Gasless” button.
   • Builds an EIP-712 “transferWithAuthorization” payload off-chain (including timestamps, nonce, etc.).
   • Prompts the user’s wallet (e.g. MetaMask) for an EIP-712 signature of that payload—no gas needed from the user at this step.
   • Sends the signed payload to the relayer via a POST request.

2. Relayer (Express + Ethers.js)

   • Listens for /relay-transfer requests.
   • Verifies and submits the user’s signed “transferWithAuthorization” on-chain by calling the USD₮0 contract’s transferWithAuthorization(...) method, paying the FLR gas itself.
   • Returns the resulting on-chain transaction hash back to the front-end.

This setup lets end users move USD₮0 tokens without holding any FLR—they only sign a message, and the relayer covers the gas.

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Step by step guide:

Clone the repository:

git clone https://github.com/vmmunoza/Gasless-USDT0-Flow.git

And make sure you comply with all relevant dependencies (Node.js, npm, and EOA with FLR tokens for the relayer).

1. Copy the example file

In your project root (where you see .env.example, frontend/ and relayer/), open a PowerShell or terminal and run:

copy .env.example .env

This creates .env with all the placeholders.

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2. Fill in the relayer settings

Open .env in your editor. In the back‑end section, set:

# — Flare RPC & USD₮0 contract 
FLARE_RPC_URL=…        # e.g. https://rpc.flare.network   or http://127.0.0.1:8545 for local
USD0_ADDRESS=…         # the USD₮0 token contract you want to use

# — Relayer credentials
RELAYER_PRIVATE_KEY=…  # a private key of an account with FLR (or test FLR) on that network
PORT=3000              # (or your preferred port)

• Note 1: If you’re demoing locally, you can point FLARE_RPC_URL at your Hardhat node and use one of the “Account #” private keys printed by npx hardhat node. ( On Coston2/testnet, use an account you’ve topped up with test FLR.)
• Note 2: The current project setup has been implemented on mainnet.

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3. Verify the front‑end wiring

Still in the same .env, confirm (or adjust) the front‑end vars:

VITE_FLARE_RPC_URL=${FLARE_RPC_URL}
VITE_USD0_ADDRESS=${USD0_ADDRESS}
VITE_RELAYER_URL=http://localhost:${PORT}

Vite will automatically expose any VITE_… keys to your React code via import.meta.env.

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4. Install dependencies

Now pull in all the packages:

# In project root
npm install

# (Optional: if you prefer per‑folder installs)
cd relayer && npm install && cd ../frontend && npm install && cd ..

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5. Launch the application

Open two terminals:

1. Relayer

   cd relayer
   npm run start

   You should see Listening on http://localhost:3000.

2. Front‑end

   cd frontend
   npm run dev

   Your browser should open the demo form.

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Once both services are running, head to the React UI, fill in a recipient and amount, sign the MetaMask prompt, and watch the USD₮0 move—all without the user holding any FLR.

You can visit the complete documentation section at the Flare Dev Hub

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NEW:

DeepWiki - https://deepwiki.com/vmmunoza/Gasless-USDT0-Flow

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Note: There's an additional branch for testing new UX improvements. If you'd like to contribute, it's a good branch to open a PR request.