GenLayer Testnet Faucet

The official faucet for GenLayer Testnet Asimov. Claim free GEN tokens to build and test on the network.

Live at testnet-faucet.genlayer.foundation

Features

• 100 GEN per claim — enough to get started building
• Rate limiting — 1 claim per wallet per 24h, 5 claims per IP per 24h
• Balance threshold — wallets with >1,000 GEN are ineligible
• CAPTCHA protection — Cloudflare Turnstile to prevent abuse
• Concurrent safety — Redis-based locking prevents double-sends
• Fair counting — rate limits only consumed after successful transaction
• Add network — one-click MetaMask/wallet integration for Testnet Asimov

Tech Stack

• Next.js 16 (App Router, TypeScript)
• Tailwind CSS v4
• viem for blockchain interactions
• Upstash Redis for rate limiting and statistics
• Cloudflare Turnstile for bot protection
• Deployed on Vercel

Network Details

Parameter	Value
Network	GenLayer Testnet Asimov
Chain ID	4221
Currency	GEN (18 decimals)
RPC	https://zksync-os-testnet-genlayer.zksync.dev
Explorer	explorer-asimov.genlayer.com

Getting Started

Prerequisites

• Node.js 18+
• An Upstash Redis instance
• A Cloudflare Turnstile site key and secret
• A funded wallet on GenLayer Testnet Asimov

Setup

1. Clone the repo:

git clone https://github.com/genlayer-foundation/testnet-faucet.git
cd testnet-faucet

2. Install dependencies:

npm install

3. Copy the env template and fill in your values:

cp .env.example .env.local

4. Configure environment variables (see below).

5. Start the dev server:

npm run dev

The app will be running at http://localhost:3000.

Environment Variables

Variable	Description	Required
FAUCET_PRIVATE_KEY	Private key of the funded faucet wallet	Yes
RPC_URL	GenLayer Testnet RPC endpoint	Yes
NEXT_PUBLIC_TURNSTILE_SITE_KEY	Cloudflare Turnstile site key	Yes
TURNSTILE_SECRET_KEY	Cloudflare Turnstile secret key	Yes
KV_REST_API_URL	Upstash Redis REST URL	Yes
KV_REST_API_TOKEN	Upstash Redis REST token	Yes
NEXT_PUBLIC_EXPLORER_URL	Block explorer URL	No
NEXT_PUBLIC_CHAIN_ID	Chain ID (default: 4221)	No
CLAIM_AMOUNT	GEN per claim (default: 100)	No
NEXT_PUBLIC_CLAIM_AMOUNT	Displayed claim amount (default: 100)	No
BALANCE_THRESHOLD	Max recipient balance (default: 1000)	No
NEXT_PUBLIC_APP_URL	Canonical URL for metadata	No

For local development, Turnstile provides test keys that always pass:

NEXT_PUBLIC_TURNSTILE_SITE_KEY=1x00000000000000000000AA
TURNSTILE_SECRET_KEY=1x0000000000000000000000000000000AA

Deploy to Vercel

API

POST /api/claim

Request a token claim.

{
  "address": "0x...",
  "turnstileToken": "..."
}

Success (200):

{
  "success": true,
  "txHash": "0x...",
  "explorerUrl": "https://explorer-asimov.genlayer.com/tx/0x..."
}

Rate limited (429):

{
  "success": false,
  "error": "This address has already claimed GEN in the last 24 hours.",
  "retryAfter": 43200
}

GET /api/stats

Public statistics endpoint (cached for 30s).

{
  "totalClaims": 1234,
  "uniqueAddresses": 567
}

Security

The claim flow performs the following checks in order:

1. Input validation (valid Ethereum address format)
2. Cloudflare Turnstile CAPTCHA verification
3. IP rate limit check (5 per 24h)
4. Address rate limit check (1 per 24h)
5. Recipient balance threshold check (<1,000 GEN)
6. Redis lock acquisition (prevents concurrent claims)
7. Faucet balance check (sufficient funds)
8. Transaction send
9. Rate limit and stats recorded (only on success)
10. Lock release

License

MIT