Crypto Gloss

Etherscan

Etherscan is the world’s most widely used blockchain explorer, providing a free, searchable interface to all data on the Ethereum blockchain. Founded in 2015 by Matthew Tan, Etherscan is the first stop for anyone needing to verify a transaction, check a wallet balance, audit a smart contract, or trace funds on Ethereum. While “blockchain explorer” is the category, Etherscan has evolved into a comprehensive analytics platform — including token tracking, gas fee tools, label databases, contract verification, and APIs used by thousands of DeFi protocols and analytics tools.

Core Features

The main features are described below.

Transaction Lookup

  • From / To addresses
  • ETH value transferred
  • Gas used and gas price paid
  • Input data (decoded ABI calls if contract is verified)
  • Token transfers triggered by the transaction
  • Internal transactions (contract-to-contract calls)

Wallet / Address View

  • Current ETH and ERC-20 token balances
  • Full transaction history
  • NFT holdings (ERC-721/1155)
  • ENS name (if linked)

Smart Contract Verification

  • Read the contract’s source code
  • Call read functions directly in a browser interface
  • Write to the contract from a connected wallet (without using a custom frontend)

This verification process is standard practice — any contract deployed without verified source is considered suspicious by the community.

Gas Tracker

Etherscan’s Gas Tracker (etherscan.io/gastracker) shows:

  • Current base fee and suggested priority fee in gwei
  • Historical gas price chart
  • “Safe,” “Standard,” and “Fast” fee estimates

One of the most-visited tools in Ethereum, used by millions of users before sending transactions.

Token and Protocol Data

  • ERC-20 tokens: Track total supply, holder count, transfer history
  • ERC-721/1155 NFTs: Track collections, individual token IDs, transfer history
  • DeFi protocols: View contract state, collateral levels, pool reserves
  • Token approvals: Etherscan’s “Token Approval Checker” shows all outstanding token approvals for a wallet — critical security tool for revoking unnecessary permissions

Labels and Tags

Etherscan maintains a crowd-sourced label database tagging addresses as:

  • Exchange hot wallets (Coinbase, Binance, Kraken)
  • DeFi protocols
  • Bridges
  • Known scam/exploit addresses
  • Notable wallets (Vitalik, etc.)

Ecosystem

Etherscan launched explorers for other EVM-compatible chains:

  • Basescan (Base)
  • Arbiscan (Arbitrum)
  • Polygonscan (Polygon)
  • Optimistic Etherscan (Optimism)
  • BscScan (Binance Smart Chain)

For non-EVM chains: Solscan (Solana), Mintscan (Cosmos), Blockstream.info (Bitcoin).

API

Etherscan’s API (free and paid tiers) is used by:

  • Most crypto wallets (balance lookups)
  • DeFi protocols (contract state verification)
  • Analytics platforms (Dune, Nansen, The Graph)
  • Tax software (Koinly, CoinTracker)

Free tier: 5 calls/second, most endpoints accessible.

Related Terms

Sources

  1. Etherscan (2015). “Introducing Etherscan — An Ethereum Blockchain Explorer.” etherscan.io/about.
  1. Victor, F. (2020). “Address Clustering Heuristics for Ethereum.” FC 2020.
  1. Ethereum Foundation (2023). “Contract Verification Best Practices.” Solidity Documentation.
  1. Chainalysis (2023). “Crypto Crime Trends.”
  1. Schoemaker, R. (2021). “Transparency in Decentralized Finance: The Role of Public Block Explorers.” SSRN.