Quick summary
This guide shows how to add custom networks to the MetaMask software wallet (both extension and mobile), with concrete RPC and Chain ID examples, safety checks, and reproducible tests. If you searched for "how to add polygon to metamask wallet" or "how to add polygon network to metamask" (or mobile variants like "how to add smart chain to metamask mobile"), you'll find step-by-step instructions here plus a safety checklist.
I run these changes daily when testing DeFi dApps, so I explain exactly how I verified each step (so you can repeat it). I've made mistakes here before, like adding an incorrect Chain ID and sending tokens to the wrong network — learned the hard way. And yes, double-check the Chain ID before sending funds.
Why add custom networks to MetaMask?
Adding a custom network (via a custom RPC) lets a software wallet interact with EVM-compatible chains beyond the default list. That unlocks lower-fee swaps, L2 activity, and access to specific DeFi apps. But there are trade-offs:
- Advantages: faster transactions on L2s, cheaper gas for frequent trading, and access to chain-specific dApps.
- Disadvantages: using third-party RPCs can expose metadata to the node operator; misconfigured Chain IDs can break transactions or produce token loss (send a test amount first).
Which fields matter most? The RPC URL and Chain ID. Everything else is convenience. (More on that below.)
The fields that actually matter (RPC, Chain ID, symbol)
When you click Add Network you'll be asked for five fields. Here are what they mean and why they matter:
- Network Name: for your reference only.
- New RPC URL: the endpoint your wallet uses to read blocks and submit transactions. Never trust a random RPC URL pushed by a website.
- Chain ID: numeric chain identifier (e.g., Polygon Mainnet = 137). This must match the network or your transactions will be invalid.
- Currency Symbol: how your wallet labels native gas (MATIC, BNB, AVAX, etc.).
- Block Explorer URL: optional, but helpful to verify transactions.
If you want to add Polygon specifically, you can follow the dedicated walkthrough at add-polygon-to-metamask. For Smart Chain (BSC) mobile guidance see add-bsc-smart-chain-to-metamask.
Step-by-step: how to add Polygon to MetaMask (extension)
This answers the classic search: how to add polygon to metamask wallet.
- Open the MetaMask extension in your browser.
- Click the network dropdown at the top (it shows the current network).
- Choose "Add Network" (or "Add a network manually").
- Enter these example values for Polygon Mainnet:
- Click Save, then switch to the new network.
- Send a very small test amount (e.g., $1 worth) of the native token to yourself to confirm connectivity.
If you want a focused guide specifically on adding Polygon, see add-polygon-to-metamask.
Step-by-step: how to add Polygon / Smart Chain to MetaMask mobile
Many people ask "how to add polygon to metamask mobile" or "how to add smart chain to metamask mobile". The mobile UI is similar.
- Open the MetaMask mobile app (iOS/Android).
- Tap the menu (top-left) and go to Settings > Networks > Add Network.
- Fill the same fields listed above (Network Name, RPC URL, Chain ID, Symbol, Explorer).
- Save and then tap the network selector to switch networks.
Example Smart Chain (BSC) values for the mobile form (for reference only):
But don't paste RPCs you find in comment sections — verify the source.
Quick comparison: extension vs mobile
| Task |
Extension (desktop) |
Mobile (iOS/Android) |
| Menu path |
Network dropdown → Add Network |
Menu → Settings → Networks → Add Network |
| Copy/paste RPCs |
Easy with keyboard |
Easy, but double-check fields before saving |
| Switching networks |
Instant in most cases |
Instant but UI differs slightly |
| Best for testing dApps |
Desktop dApps via browser |
Mobile dApp browser or WalletConnect |
How I tested this (so you can replicate)
I ran the same steps on both extension and mobile, using public RPC endpoints and a small live value (about $1 worth of native token) to verify submission and confirmations.
Steps I repeated for reproducibility:
- Add network using the fields above.
- Switch to the new network in the wallet UI.
- Send a small native-token tx to another address I control.
- Confirm the tx on the block explorer using the Block Explorer URL.
- Connect the wallet to a simple dApp via WalletConnect (mobile) or the injected provider (desktop) and check the dApp shows correct chain ID.
I repeated these steps 3 times and recorded whether the RPC timed out, how long the first block load took, and whether token balances showed automatically. You can repeat the same checks.
Security checklist when adding custom RPCs
- Verify RPC URLs from official chain docs or recognized explorers, not social posts.
- Confirm the Chain ID numerically (e.g., 137 for Polygon, 56 for Smart Chain).
- Send a tiny test amount first. Always.
- Avoid adding networks proposed by unknown websites via a popup.
- Use a hardware wallet for large balances and connect it to MetaMask (see integrate-hardware-ledger-trezor).
- Revoke token approvals for dApps you no longer use (see token-approvals-and-revoke).
- Back up your seed phrase offline; avoid cloud backups unless you understand the risks (read backup-and-recovery-seed-phrase).
But don't panic — adding networks is routine when you follow these steps.
Troubleshooting: common errors and fixes
- RPC timeout or connection error: try an alternative RPC endpoint, or wait and retry — some public RPCs throttle.
- Wrong Chain ID: correct the Chain ID to match the network; transactions will fail otherwise.
- Tokens not showing: add the token contract manually (see add-custom-tokens-to-metamask).
- Network shows but dApp says "wrong network": force-refresh the dApp and ensure MetaMask is set to the same Chain ID.
If things still fail, consult troubleshooting or the network-specific page (for Polygon, see add-polygon-to-metamask).
Who this works best for — and who should look elsewhere
Best for:
- Active DeFi users who need occasional access to L2s and EVM chains.
- Mobile-first users who connect to dApps via WalletConnect.
Should look elsewhere:
- People who prefer keeping large balances in a hardware-only workflow without a connected software wallet.
- Users uncomfortable verifying RPC URLs or managing token approvals.
If your daily workflow involves frequent swaps, adding networks reduces friction. If you rarely move funds, a hardware-first approach is safer.
FAQ
Q: Is it safe to keep crypto in a hot wallet?
A: Hot wallets are convenient for DeFi activity but carry more risk than offline storage. Use seed phrase backups, hardware wallets for larger balances, and daily security practices (see security-and-safety).
Q: How do I revoke token approvals after connecting to a dApp?
A: Use the token approvals revoke tool inside the wallet or a third-party revocation site, and double-check contract addresses. See token-approvals-and-revoke for step-by-step instructions.
Q: What happens if I lose my phone?
A: If you have your seed phrase backed up offline, you can restore your wallet on another device (see backup-and-recovery-seed-phrase). If not, recovery is unlikely.
Q: Where can I find step-by-step mobile install details?
A: See install-metamask-mobile and mobile-setup for first-time setup guidance.
Conclusion and next steps
Adding custom networks to MetaMask is a straightforward way to expand your DeFi access. Follow the exact fields for RPC and Chain ID, test with a small amount, and verify via the block explorer. In my experience the small test transaction saves headaches later.
If you want a deep walkthrough for a particular chain, check the chain-specific pages: add-polygon-to-metamask, add-bsc-smart-chain-to-metamask, and add-avalanche-avax-to-metamask. For safety-focused reading, see security-and-safety and backup-and-recovery-seed-phrase.
Ready to try? Add one network with a tiny test transaction, confirm it on the explorer, and then connect to the dApp you need. But always start small.
