Etherscan API

What it is

The Etherscan API is the data behind the Etherscan block explorer, sold as a REST interface: native and token balances, an address's normal, internal and token-transfer history, event logs by address and topic, verified contract source and ABI, gas figures, ENS resolution, and daily chain statistics. It is one card and the explorer is not on it — the website is free to browse and is bought by nobody; this is the product a developer pays for when they want the same answers in their own code.

V2 is the version to know. One key and one base URL now cover every chain Etherscan runs an explorer for, chosen with a chainid parameter, where it used to be a separate key and host per explorer. The docs list 63 networks on 4 October 2026, 33 of them mainnets and 30 testnets. The V1 per-chain endpoints are closed: a V1 call that day returned an error pointing at the migration guide, so any old script or tutorial written against them has stopped working.

It sits in on-chain analytics because what it returns is chain state, read and indexed — not prices from venues. It is the narrowest kind of product in that category: per-address and per-contract lookups rather than a query engine, with no SQL, no joins across addresses and no decoded protocol tables. That narrowness is also why it is the default answer to "what happened at this address", and why so many wallets, tax tools and dashboards are built on it.

Pricing

Seven plans, read off the pricing page on 4 October 2026. Free at 0 USD, Lite at 49, Standard at 199, Advanced at 299, Professional at 399 and Pro Plus at 899 USD a month, plus a quoted Dedicated plan. Quarterly billing takes 10% off and yearly 15%.

Two separate ladders climb inside that list, and the pricing table hides one of them in an asterisk:

• Throughput and endpoints. Free gives 3 calls a second and up to 100,000 a day, cumulative across every key on the account, so making a second key buys nothing. Lite raises it to 5 a second and opens every chain. Standard is the first plan with the 30 endpoints marked PRO, and those are the ones a research job usually wants: historical balance at a block, token holder lists and counts, an address's full token holdings, historical ERC-20 supply, top holders, the daily network series and historical ETH price. The address name-tag and label endpoint is on Pro Plus only.
• The licence. Free, Lite and Standard are licensed for personal and research use. The API terms, last updated 1 October 2026, define commercial use as anything offered to third parties (free or paid), anything that earns revenue directly or indirectly, and anything operated by or for a business, protocol, foundation or DAO — internal analytics, compliance and accounting included. So a 199 USD Standard plan with every PRO endpoint still may not sit behind a company's internal dashboard. Advanced, at 299 USD, is the floor for that.

Data & coverage

The 33 mainnets are EVM chains only — Ethereum, Arbitrum One, Polygon, Base, BNB Smart Chain, OP Mainnet, Avalanche C-Chain, Linea, Blast, Mantle, Sonic, Unichain, Berachain, Monad, HyperEVM, Plasma and others. Bitcoin and Solana are not among them, and neither is any non-EVM chain. On the free plan, Base, BNB Smart Chain, OP Mainnet, Avalanche C-Chain and Gnosis return nothing except contract source and ABI, which the docs keep open on every chain at every tier. The notices on the chains page that day said opBNB support ends on 12 October 2026, and that Robinhood Chain and Arc move behind the Lite plan on 16 October.

The endpoint overview lists 94 endpoints across fifteen modules, one of them a beta. Most are per-address or per-transaction lookups, paged with page, offset and sort. There are no push channels — no websockets and no webhooks — so watching an address means polling it within your per-second budget. The proxy module passes standard node calls through for the chain head; the indexed endpoints are as current as the explorer's own index.

One endpoint is a curiosity worth knowing about: a beta call returning an address's Polymarket trades, which makes this an Ethereum explorer's API that answers a prediction-market question.

Integrations

There is an official CLI, installable through Homebrew or npm, and two official MCP servers over Streamable HTTP. The authenticated server carries all 21 tools and counts against your plan's limits; the keyless one carries 16, drops every PRO tool and is rate-limited on its own. On 4 October 2026 an unauthenticated initialize against the keyed server returned 401, and the keyless server answered it, identifying itself as etherscan-mcp 2.4.0. The docs say plainly that directory listings calling themselves "Etherscan MCP" are unofficial — worth reading before pasting a key into one. The vendor also publishes installable agent skills for tracing fund flows, reviewing a verified contract and explaining a transaction.

Limitations

• The licence is the real price. Every plan below 299 USD a month is for personal and research use only, and the definition of commercial use reaches internal business reporting. A hobby project that turns into a product changes plan the day it does.
• Attribution is required on every plan. Wherever API data or results derived from it are displayed or published — an app, a dashboard, a report, a research paper — the terms require a visible "Powered by Etherscan.io APIs" credit with a link where practicable.
• No resale, no data product. Even a commercial plan may only display the data inside an application that does meaningfully more than republish it. Offering it onward as an API, a feed, a downloadable dataset or a bulk export is prohibited, and the terms add a clause against building software that competes with Etherscan's own services.
• One app per subscription. The terms grant one app licence per paid plan, and the pricing table repeats it on the top tiers.
• Lookups, not analysis. There is no query language, no cross-address aggregation and no decoded protocol data. Questions like "every holder of this token who also used that contract" are not one call, and on a per-second budget they may not be practical at all.
• Five large mainnets are paid-only. A free key that works on Ethereum and Arbitrum returns nothing useful on Base or BNB Smart Chain, which surprises people whose test chain was free.

Alternatives

For questions that span many addresses or need protocol-level tables, a SQL engine over decoded chain data is the better fit — Dune for public dashboards and a free query tier, Allium for warehouse-scale delivery, or Bitquery for GraphQL with streaming. For labels and entity attribution as the product rather than a Pro Plus add-on, Nansen is the comparison.