The short answer
Before accepting a network prompt, check the chain ID against an independent list, prefer an RPC endpoint published by the network itself, and remember that your wallet does not authenticate any of the details a site submits. A malicious provider can misreport balances, withhold transactions and log your activity.
What the prompt actually installs
A network entry holds a display name, a chain ID, an RPC endpoint, a currency symbol and usually a block explorer URL. The site supplies all of it through the standard wallet_addEthereumChain request defined in EIP-3085.
Your wallet checks that the submitted chain ID is well formed. It does not check that the name matches the chain ID, that the RPC endpoint is honest, or that the currency symbol is right. Those are your job.
How to verify before accepting
MetaMask’s guidance is to look up the chain ID and network name on an independent list such as Chainlist, and it is explicit that a network which does not appear there at all is either extremely new or of questionable quality.
Three checks cover most of the risk. Does the chain ID match the network you were told this is? Is the RPC endpoint one the network itself publishes, or one from a provider you already use? Does the currency symbol match the network’s actual gas asset — POL for Polygon PoS, BNB for BNB Smart Chain, ETH for Ethereum and its major layer 2s?
A mismatch in any of these is a reason to decline and add the network manually from the network’s own documentation.
Why the RPC endpoint matters most
The endpoint is where your wallet reads state and sends transactions. MetaMask warns plainly that you should trust the provider, because a malicious one can lie about the state of the blockchain, withhold transactions, and record your network activity and IP address.
A dishonest endpoint does not need your keys to cause harm. Showing you a balance that is not there, or quietly failing to broadcast, is enough to make you act on false information.
After adding, and when to remove
Once added, a network stays in your switcher and looks as legitimate as the ones that came built in. Review the list occasionally and remove entries you no longer recognise or use.
Keep an eye out for duplicates: two entries with the same display name and different chain IDs or endpoints, which is exactly what a spoofed network looks like. If a familiar network suddenly behaves oddly — wrong balance, transactions that never appear on the explorer — check which entry you are actually on before concluding something is wrong with your funds.
Frequently asked
Is it dangerous to add a network?
Adding a network does not expose your keys, but it does tell your wallet to trust an endpoint for reading state and broadcasting transactions. A dishonest endpoint can misreport balances and withhold transactions, which is enough to cause real losses through bad decisions.
How do I check a chain ID?
Look it up on an independent list such as Chainlist, or in the network’s own documentation, and compare it with what the prompt shows.
Can I add a network manually instead?
Yes, and it is the safer habit for anything unfamiliar: take the details from the network’s own documentation rather than from a site’s prompt.
What if a network I already use starts behaving strangely?
Check which entry is selected and what endpoint it uses before assuming your funds are affected. Confirm balances against a block explorer, which does not depend on your wallet’s endpoint.
Before you act
- Verify the chain ID against an independent list before accepting.
- Prefer an RPC endpoint published by the network or a provider you already trust.
- Check the currency symbol matches the network’s real gas asset.
- Review and remove unfamiliar or duplicate network entries.
Sources & further reading
- MetaMask: how to add a custom network RPC
What a network entry contains and how it is added.
- MetaMask: verifying custom network information
Verify against an independent list; a malicious provider can misreport state and log activity.
- EIP-3085: wallet_addEthereumChain
The standard request a site uses, and the chain ID validation rules.
- Polygon: network details
Example of a network publishing its own endpoint and chain details.
Sources checked on 18 September 2026. Network features and platform support can change; check the relevant provider before acting.
AI-assisted editorial content; no independent expert review or transaction verification is claimed. Tokens and bridges carry issuer, market and smart-contract risks. This is educational information, not investment advice. Read our editorial policy.