What Etherscan actually is
Etherscan is a hosted index of the Ethereum blockchain with a web front end on top. It runs its own nodes, writes every block, transaction, log and state change into a database, decodes what it can into human-readable form, and serves the result as web pages and as an API. It has done this since 2015, which on Ethereum's timeline means since almost the beginning.
That longevity is why it matters more than its feature list suggests. When a wallet shows you a token name, when a portfolio tracker resolves a contract, when a security researcher posts a link to prove a point — the underlying source is very often Etherscan. It has become infrastructure by accumulation rather than by design, and a surprising amount of the ecosystem would need a plan B if it disappeared tomorrow.
The commercial reality behind it is worth stating plainly, because it is the root of both the good and the bad here. Etherscan Ltd is a private company. It is not a foundation, it is not funded by the Ethereum Foundation, and it has no obligation to publish its code or explain its decisions. It sells API plans and advertising. Everything in this review follows from that.
Contract verification, and why it is the real product
If you take one thing from this review, take this: Etherscan's genuine moat is not the explorer, it is the verified source code registry sitting behind it.
A deployed contract on Ethereum is bytecode. It is deterministic, it is auditable in principle, and it is completely unreadable in practice. Verification is the process of submitting the original Solidity or Vyper source, along with the exact compiler version and optimisation settings, so that anyone can recompile it and confirm the output matches the bytecode on chain. Etherscan checks that match and then publishes the source.
The result is that "is this contract verified on Etherscan" has become a first-order safety question across the whole ecosystem, asked by people who have never written a line of Solidity. That is enormous informal power for a private company to hold, and it works because the check is real — you can reproduce it yourself, which is the property that makes it trustworthy rather than merely authoritative.
The Read and Write tabs
For a verified contract, Etherscan generates an interface from the ABI. The Read Contract tab calls view functions and shows you the answer with no wallet involved and no transaction. The Write Contract tab connects a wallet and lets you call state-changing functions directly.
This is more useful than it sounds and more dangerous than it looks. It is the standard escape hatch when a project's own front end goes down and people need to withdraw from a contract directly, and it has rescued a lot of money over the years. It is also a raw interface with no guard rails: nothing stops you passing the wrong decimals to an amount field and approving a spend a million times larger than you intended. Read our guide on checking a contract before you sign before you use it in anger.
Proxies, handled properly
Most significant contracts today are proxies — a thin, permanent address that delegates all logic to a separate implementation contract which can be swapped out. A naive explorer shows you the proxy's own bytecode, which is about forty lines of delegation boilerplate and tells you nothing.
Etherscan detects the common proxy patterns, resolves the implementation, and gives you a toggle between "Read as Proxy" and the raw contract. It gets this right consistently. Several competitors do not, and the failure is silent — you are looking at a real contract and drawing a conclusion about the wrong code.
The V2 API: what the free tier really gives you
Etherscan's API changed shape meaningfully with V2, and the change is good for most people. Rather than holding a separate key for Etherscan, BscScan, Arbiscan, PolygonScan and the rest, you now hold one key and pass a chainid parameter to choose the network.
GET https://api.etherscan.io/v2/api
?chainid=8453
&module=account
&action=balance
&address=0x...
&apikey=YOUR_KEYChain ID 1 is Ethereum, 8453 is Base, 42161 is Arbitrum One, 137 is Polygon, 56 is BNB Smart Chain. Around sixty networks are addressable this way, and for anyone maintaining a multi-chain application that consolidation removes a genuinely tedious amount of key management.
Which chains a free key actually reaches
Addressable and included are not the same thing, and this is where the published summaries stop being useful. We registered a free key and put the same call against a spread of chains on 17 September 2026, three times each to rule out a transient. The results were stable, and not what the marketing implies.
The free key answered on Ethereum, Polygon, Arbitrum One, Linea, Blast, Mantle, Fraxtal, opBNB, Moonbeam and Sepolia. It was refused outright on Base, BNB Smart Chain, Optimism, Gnosis and Avalanche, each returning Free API access is not supported for this chain. Scroll, Fantom, Polygon zkEVM, Arbitrum Nova, Cronos and Holesky did not resolve as V2 chain IDs at all on that account.
Read that list again, because the shape of it matters more than its length. The chains behind the paywall are not obscure — Base, BNB Smart Chain and Optimism are three of the busiest EVM networks in use. The chains still free skew towards the newer and quieter end. If your project touches Base or BNB, the free tier does not cover you, and finding that out in a staging environment is better than finding it out in production.
The limits, stated honestly
The free tier is 5 calls per second and 100,000 calls per day. That is generous by current standards — several competitors have tightened considerably — and the per-second limit is shared across chains, not granted per chain, which is the detail people miss when they plan capacity.
Free-tier chain coverage was reduced during 2026. Etherscan's explanation is that block speeds and transaction volumes on several networks rose far enough to strain the service, and it advertises roughly 90 per cent chain coverage on free with a discounted Lite plan for the rest. That percentage is doing a lot of work: it counts chains, not usage, and the excluded ones are disproportionately the busy ones, as the test above shows. Verified-contract endpoints — source, ABI, verification status — do remain free across supported networks, which is the right call, because that is the part the wider ecosystem depends on.
You cannot call it from a browser
Because the key is a secret, an Etherscan request has to go through a server you control. This sounds obvious and is routinely ignored; keys leak from page source constantly. It is also the practical reason a static site cannot use Etherscan directly, and why the lookup tool on this site reaches for keyless APIs first. Our explorer API comparison sets out which endpoints work from a browser and which do not.
What Etherscan learns when you look something up
This is where Etherscan scores worst in our ranking, and it is worth being precise about why, because the criticism is often made badly.
Etherscan does not deanonymise the blockchain. It cannot — the chain does not contain identities. What it does is observe that a particular browser, with a particular IP address and a particular fingerprint, repeatedly looked up one specific address. If that address is your wallet, the inference is not subtle.
The site also loads third-party resources, sets cookies, and operates as a commercial business in a sector where address attribution has obvious market value. We are not alleging that Etherscan sells browsing data. We are observing that the data exists, that the incentive exists, and that you have no way to verify what happens to either, because the system is closed.
The mitigations are ordinary. Use a VPN or Tor. Do not log in. Better, use an explorer that cannot learn anything because it runs on your own hardware — Otterscan against your own Erigon node is the clean answer, and Blockscout is the middle path if you want a hosted interface from a project whose code you can at least read. Our guide on what an explorer learns about you works through the threat model properly.
Using it day to day
Three things on Etherscan get used far more than everything else combined, and they are worth knowing properly.
The gas tracker
Ethereum's fee market has been considerably calmer since EIP-1559 introduced a base fee that adjusts algorithmically, but the tracker still earns its place for timing a non-urgent transaction. The number that matters is the base fee, because that portion is burned and cannot be negotiated; the priority fee is what you actually control.
The token approval checker
Every time you use a decentralised exchange, you grant a contract permission to move a token on your behalf, and that permission is frequently unlimited and effectively permanent. People accumulate dozens of these without realising. The approval checker lists them and lets you revoke.
We would call this the single most useful safety feature on the site. When a protocol is exploited, the losses often fall on people who approved it two years ago and forgot. Checking this list once a quarter is a genuinely sensible habit, and the same tool exists on BscScan, where the case for using it is stronger still.
Internal transactions
A plain transaction list is misleading on Ethereum, because value moved by a contract calling another contract does not appear as a normal transaction. Etherscan surfaces these as internal transactions on a separate tab. If an address looks empty and should not be, this is usually where the activity went. This is a recurring source of confusion when people check whether a withdrawal arrived.
From our testing
We ran the same failed contract call through eight EVM explorers. Etherscan was one of only three that showed the revert reason string in plain text rather than a raw hex error. When you are debugging why a transaction consumed gas and did nothing, that one field saves a great deal of time.
So should you use it?
For reading contracts, yes, and there is no close second. The verification registry is the product, the ecosystem has standardised on it, and no alternative has the coverage.
For routine lookups, it depends on what you mind. If you are checking a public contract or a well-known protocol wallet, the privacy question is academic. If you are repeatedly checking your own balance, you are handing a commercial company a reliable association between you and an address, every single time, and you should think about whether you would say that out loud.
For building, take the free key. It is a good deal, the multi-chain consolidation is real, and the contract endpoints staying free across all networks is the right instinct. Just put it behind your own server, and have a fallback — we would suggest Blockscout — for the chains that free tier no longer covers.
And keep a second explorer in the habit. Not because Etherscan is often wrong, but because an index is a rendering of the chain rather than the chain itself, and the way you catch a rendering error is by looking at a different one. Blockchair or 3xpl takes ten seconds and has caught more than one confused reading for us.