How to Read a Blockchain Explorer (Etherscan, Solscan)
Blockchain explorers are the window into the transparent ledger of cryptocurrencies like Ethereum and Solana. They let you verify any transaction, check the balance of any address, and confirm the authenticity of a smart contract — all without trusting a third party. For beginners, these tools can feel overwhelming because of the raw data they display. This guide will walk you through the essential skills: reading a transaction from pending to confirmed, spotting token approvals that could put your funds at risk, and verifying that a contract address is genuine.
By the end, you’ll be able to use Etherscan (for Ethereum and EVM chains) and Solscan (for Solana) with confidence. You’ll understand the difference between a simple send and a complex swap, know how to revoke harmful approvals, and avoid falling for fake contract addresses. These are the foundational skills every self-custody user needs.
- Blockchain explorers are free, public search engines for transactions, addresses, and contracts.
- A transaction hash (txid) is your receipt; you can track it from pending to confirmed and see fees, block number, and status.
- Token approvals give dApps permission to spend your tokens – monitor and revoke them regularly via the explorer’s approval viewer.
- Always verify a smart contract’s source code on Etherscan/Solscan before interacting; avoid unverified contracts.
- Internal transactions (traces) reveal hidden sub-calls, useful for debugging failures or spotting attacks.
- Bookmark the official explorer URLs and never share your seed phrase – explorers only need your public address.
What Is a Blockchain Explorer and Why Do You Need One?
A blockchain explorer is a search engine for the blockchain. It indexes all blocks, transactions, addresses, and smart contracts into a readable website. Etherscan etherscan.io does this for Ethereum and many EVM-compatible chains; Solscan solscan.io provides the same for Solana. You can look up any transaction hash, wallet address, or contract address and see its entire history.
Why use one? Three core reasons:
- Verification – Confirm that a transaction actually went through and has enough confirmations.
- Security – Check if a dApp has permission to spend your tokens (token approvals) and revoke it if needed.
- Due diligence – Before interacting with a smart contract, verify its source code is published and matches the official project.
Without an explorer, you’re blindly trusting wallets and dApps. With it, you gain true self-sovereignty.
Getting Started: How to Open an Explorer and Search for a Transaction
Navigate directly to etherscan.io or solscan.io in your browser. The homepage shows a prominent search bar. You can paste almost anything into it:
- A transaction hash (0x… on Ethereum, a base58 string on Solana) – shows details of that specific transfer.
- A wallet address – shows the balance, token holdings, and full transaction history of that account.
- A contract address – shows the contract’s code, interactions, and token transfers.
- A block number – shows all transactions in that block.
For beginners, the easiest starting point is a transaction hash from a wallet like MetaMask or Phantom. Copy the hash from the wallet’s “View on Explorer” button and paste it into the search bar. The explorer will immediately show you the transaction page.
Always double-check you are on the official domain. Scammers create fake explorers that look identical but show fake data. Bookmark the real URLs.
Tracking a Transaction: From Pending to Confirmed
When you submit a transaction, it appears in the explorer as Pending (or “Unconfirmed”). After a validator includes it in a block, it becomes Confirmed (or “Success”). The transaction page shows several important fields:
- Status – Success, Failed, or Pending.
- Block Height – the block number and how many confirmations have occurred since (the higher the number, the more secure).
- Timestamp – when the block was produced (approximate).
- From / To – the source and destination addresses.
- Value – the amount of native coin (ETH, SOL).
- Transaction Fee (Gas) – the fee paid to the validators, shown in both the native token and USD.
On Etherscan, scroll down to see the Transfer sub‑table for token movements; on Solscan, token transfers appear directly. If the transaction failed, the explorer often shows the Revert Reason (e.g., “insufficient funds” or “slippage too high”).
Decoding Transaction Details: From, To, Value, and Input Data
Beyond the basic fields, the Input Data (or Instruction Data on Solana) reveals what a smart contract was instructed to do. For a simple ETH send, this field is usually empty. But for a token swap, the input data contains a function call like swapExactTokensForTokens with encoded parameters.
Use the “Decode Input Data” button on Etherscan (if the contract is verified) to see human‑readable parameters like amountIn, amountOutMin, and path. On Solscan, the Transaction Details tab lists each instruction with its program ID and accounts involved.
What to watch for:
- Token Transfers table – shows every ERC‑20 or SPL token move inside the transaction. It lists the token symbol, amount (with decimals), and the sending/receiving address.
- Logs / Events – emit information from the contract, such as a “Transfer” event.
By reading these details, you can confirm that a swap really gave you the expected output, or detect unexpected token transfers (signs of a phishing attack).
Checking Token Approvals: How to See Which dApps Can Spend Your Tokens
When you approve a token for a dApp (e.g., “Approve USDC for Uniswap”), you are granting that contract authority to move a specific amount (or unlimited amount) of your tokens. This approval is visible on the explorer forever unless revoked. Both Etherscan and Solscan have dedicated approval viewers.
On Etherscan: Go to the token contract page (e.g., USDC’s contract) and click the Token Approvals tab. Enter your wallet address to see which spender addresses have allowances. Alternatively, use the ERC‑20 Token Approval section on your wallet’s token page under “More Info”.
On Solscan: Visit your wallet address page, click the Token Accounts tab, then the Approve subtab. It lists all delegated SPL token approvals, including the amount and delegate program.
If you see an approval you don’t recognize or a spender with unlimited allowance, you should revoke it immediately by calling the approve function with a zero amount. Tools like Revoke.cash simplify this, but you can also do it manually via the explorer by writing a transaction.
High‑risk approvals are the number one cause of drained wallets after seed‑phrase leaks. Check token approvals at least once a month.
Verifying a Smart Contract Address: How to Know It’s Legit
Before you interact with a smart contract (e.g., to stake tokens or buy a new token), verify the address is legitimate. A valid contract should have verified source code on Etherscan or Solscan. Look for a green checkmark or the label “Verified” next to the contract address.
Steps on Etherscan:
- Search the contract address.
- Click the Contract tab.
- Check if the Source Code is visible and matches the official project’s GitHub or documentation.
- Look at the Contract Creator address – does it belong to the known team? Is it a brand new address?
Steps on Solscan:
- Search the program ID (contract address).
- Click the Program tab.
- See the Deployer address and the Last Deployed timestamp.
- Check if the Executable Data is available (Solana programs can be verifiable if the source is published).
Never trust an unverified contract. Scammers often deploy contracts without source code and lure users to “approve” or “deposit”. If the code is hidden, do not interact. Cross‑reference the official project’s website or social media to confirm the address.
Reading Internal Transactions (Traces) for Complex Interactions
When you trade on a DEX like Uniswap or use a multi‑step protocol, the explorer’s main transaction page may only show the top‑level call. To see the internal calls — e.g., a swap that routes through two pools — click the Internal Txns tab on Etherscan (labeled “More” → “Internal Transactions”).
This trace shows each sub‑call: the contracts called, the ETH value transferred between them, and the gas used. On Solana, the equivalent is the Transaction → Instruction view, which lists each program invocation with its accounts and return data.
Why it matters: If a transaction fails, the internal trace often reveals exactly which sub‑call reverted. It’s also the best place to detect “sandwich attacks” – you may see a transaction directly before yours that manipulated the price. Reading traces takes practice, but even beginners can look for the Type of call (e.g., CALL, DELEGATECALL) and the Input bytes to understand the flow.
Use traces to verify that a supposedly simple transfer didn’t trigger hidden contract interactions.
Pro Tips: Using Filters, Exporting Data, and Staying Safe
Once you are comfortable with the basics, these features will make you a power user:
- Etherscan Filters: On your wallet’s transaction page, use the Filters dropdown to show only certain token transfers, failed txs, or interactions with a specific contract. Perfect for auditing your history.
- Export to CSV: Click the Export button to download all transactions for tax reporting or analysis.
- Watch List: Create a free account on Etherscan to add addresses or contracts to a watch list and receive email alerts for transactions.
- Solscan Tools: Use the Top Holders or Whale Transactions pages for on‑chain analysis. The Market tab shows real‑time price and liquidity.
Safety first: Always verify the domain – phishing sites like “etherscan.xyz” or “solscan.co” exist. Use browser bookmarks. Never paste a seed phrase into any explorer; they only need addresses. Finally, if a transaction seems suspicious, use an explorer to “simulate” it by checking the target address history before signing.
Frequently asked questions
What is a transaction hash (txid) and how do I find it?
A transaction hash is a unique identifier for every blockchain transaction. You can find it in your wallet (e.g., MetaMask, Phantom) under “Activity” or “History” – click the transaction and look for “View on Explorer”.
How do I know if a transaction is confirmed?
On the transaction page, look for the “Status” field. If it says “Success” (green) and shows a block number with many confirmations, it is confirmed and irreversible. “Pending” means it’s still waiting in the mempool.
What does a token approval mean, and why should I revoke it?
An approval is a permission you grant a smart contract to spend a specific amount of your tokens. If you gave unlimited approval, the contract could drain your entire balance. Revoke it by setting the allowance to 0 via the explorer or a revoke tool.
How can I verify a contract address is legitimate?
Search the contract on Etherscan or Solscan and check that the “Contract” tab shows verified source code with a green check. Cross-reference the address with the official project’s documentation or social media posts.
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