How do I add the Polygon (Matic) or Avalanche (AVAX) network to MetaMask?

Adding Polygon Network to MetaMask

1. Open MetaMask and click the network dropdown menu located at the top of the interface.

2. Select Add Network from the list, then choose Add a network manually.

3. Enter Polygon Mainnet as the network name.

4. Input https://polygon-rpc.com/ for the New RPC URL.

5. Set the Chain ID to 137 and the Symbol to MATIC.

6. Use https://polygonscan.com/ as the Block Explorer URL.

7. Click Save to complete the configuration.

Adding Avalanche Network to MetaMask

1. In MetaMask, open the network selector and click Add Network.

2. Choose Add a network manually instead of selecting from presets.

3. Type Avalanche C-Chain as the network name.

4. Paste https://api.avax.network/ext/bc/C/rpc into the New RPC URL field.

5. Enter 43114 as the Chain ID and AVAX as the currency symbol.

6. Insert https://snowtrace.io/ as the Block Explorer URL.

7. Confirm with Save to finalize the setup.

Verifying Network Configuration

1. After saving either network, return to the main MetaMask interface and confirm the selected network appears in the top bar.

2. Check if your wallet address displays correctly under the new network—no balance changes should occur automatically.

3. Initiate a small test transaction using a faucet or known contract interaction to verify connectivity.

4. Observe whether transaction hashes resolve on the respective block explorers: Polygonscan for Polygon and Snowtrace for Avalanche.

5. Ensure gas estimation functions properly within MetaMask when initiating transfers or smart contract calls.

Troubleshooting Common Connection Issues

1. If transactions remain pending indefinitely, verify that the RPC endpoint is not rate-limited or temporarily offline by testing it via curl or browser access.

2. A mismatched Chain ID will prevent MetaMask from recognizing the network—recheck values against official documentation from Polygon and Avalanche.

3. Some third-party dApps may fail to detect the network unless MetaMask’s “Show test networks” toggle is enabled in Settings > Advanced.

4. Clearing MetaMask’s cache through Settings > Advanced > Reset Account may resolve inconsistent balance displays without affecting private keys.

5. Custom RPC URLs must use HTTPS; HTTP endpoints will be rejected outright by MetaMask’s security policy.

Frequently Asked Questions

Q: Can I add both Polygon and Avalanche to MetaMask simultaneously?A: Yes. MetaMask supports multiple custom networks. Each appears as a selectable option in the network dropdown.

Q: Why does my balance show zero after switching to Polygon or Avalanche?A: Native token balances are chain-specific. MATIC or AVAX must be deposited onto their respective networks via bridges or exchanges supporting those chains.

Q: Is it safe to input custom RPC URLs into MetaMask?A: Official RPC endpoints listed by Polygon and Avalanche teams are trusted. Avoid entering unknown or unverified URLs as they could expose transaction data.

Q: Do I need separate seed phrases for each network?A: No. All networks share the same underlying Ethereum-compatible key derivation. One seed phrase controls assets across all added EVM-compatible chains.