# Explorer API Keys Setup Guide

**Purpose**: Contract verification on blockchain explorers
**Status**: Optional but recommended

---

## 🔑 Required API Keys

### Chains with Contract Verification

| Chain | Explorer | API Key Variable | Get API Key |
|-------|----------|-----------------|-------------|
| **Ethereum Mainnet** | Etherscan | `ETHERSCAN_API_KEY` | https://etherscan.io/apis |
| **BSC** | BscScan | `BSCSCAN_API_KEY` | https://bscscan.com/apis |
| **Polygon** | Polygonscan | `POLYGONSCAN_API_KEY` | https://polygonscan.com/apis |
| **Avalanche** | Snowtrace | `SNOWTRACE_API_KEY` | https://snowtrace.io/apis |
| **Base** | Basescan | `BASESCAN_API_KEY` | https://basescan.org/apis |
| **Arbitrum** | Arbiscan | `ARBISCAN_API_KEY` | https://arbiscan.io/apis |
| **Optimism** | Optimistic Etherscan | `OPTIMISTIC_ETHERSCAN_API_KEY` | https://optimistic.etherscan.io/apis |
| **Cronos** | Cronos Explorer | `CRONOSCAN_API_KEY` | https://explorer.cronos.org/register (My API Keys) |
| **Gnosis** | Gnosisscan | `GNOSISSCAN_API_KEY` | https://gnosisscan.io/apis |

---

## 📝 How to Get API Keys

### 1. Create Account
- Visit the explorer website
- Sign up for a free account
- Verify your email

### 2. Generate API Key
- Go to API section (usually under "Account" or "API")
- Click "Create API Key"
- Give it a name (e.g., "Foundry Deployment")
- Copy the API key

### 3. Add to `.env`
```bash
ETHERSCAN_API_KEY=your_actual_api_key_here
BSCSCAN_API_KEY=your_actual_api_key_here
POLYGONSCAN_API_KEY=your_actual_api_key_here
SNOWTRACE_API_KEY=your_actual_api_key_here
BASESCAN_API_KEY=your_actual_api_key_here
ARBISCAN_API_KEY=your_actual_api_key_here
OPTIMISTIC_ETHERSCAN_API_KEY=your_actual_api_key_here
CRONOSCAN_API_KEY=your_actual_api_key_here
GNOSISSCAN_API_KEY=your_actual_api_key_here
```

---

## ⚠️ Important Notes

1. **Free Tier Limits**: Most explorers offer free API keys with rate limits
   - Usually sufficient for deployment and verification
   - Check limits on each explorer's website

2. **Security**:
   - Never commit API keys to version control
   - Keep `.env` file secure
   - Rotate keys periodically

3. **Optional but Recommended**:
   - Contract verification helps users trust your contracts
   - Makes contract interaction easier
   - Required for some DeFi protocols

4. **Without API Keys**:
   - Deployment will still work
   - Contracts won't be automatically verified
   - Manual verification possible later

5. **Cronos**:
   - Use Cronos Explorer (explorer.cronos.org), not cronoscan.com
   - Forge verification requires manual UI: https://explorer.cronos.org/verifyContract
   - See [CRONOS_EXPLORER_OPERATIONS.md](../04-configuration/CRONOS_EXPLORER_OPERATIONS.md) for confirmation and API usage

---

## ✅ Verification

After adding API keys, test with:

```bash
# Test Ethereum Mainnet (if you have a deployed contract)
forge verify-contract \
  --chain-id 1 \
  --num-of-optimizations 200 \
  <CONTRACT_ADDRESS> \
  <CONTRACT_NAME> \
  $ETHERSCAN_API_KEY
```

---

## 🚀 Deployment with Verification

When deploying with `--verify` flag, Foundry will automatically use the API keys:

```bash
forge script script/DeployAll.s.sol:DeployAll \
  --rpc-url mainnet \
  --private-key $PRIVATE_KEY \
  --broadcast \
  --verify \
  -vvvv
```

The `--verify` flag uses the API keys from `.env` automatically.

---

**Status**: Optional - Deployment works without API keys, but verification requires them.