Ever found yourself staring at a transaction hash and feeling a little lost? You’re not alone. Transactions on Ethereum can look alien at first—long hex strings, a stack of confirmations, and gas numbers that jump around. But once you get the hang of the patterns, you can read a transaction like a receipt and troubleshoot faster than most support desks.
Start with the basics: an ETH transaction is a recorded state change on the blockchain. It can be a simple value transfer (ETH A -> ETH B), a contract interaction, or a contract deployment. Each transaction includes a sender, a recipient (or contract address), a value (in wei), input data, a nonce, and gas-related parameters. Those parameters are the key to performance and cost. Miss them and your tx either sits pending or burns more ETH than you expected.
1) Decoding an ETH transaction — what to look for
Look at the transaction hash first — that’s your unique ID. Then check the block number and confirm count. If it’s pending, you’ll see no block and no confirmations. The sender and recipient addresses tell you who initiated the action and where it targeted. If the recipient is a contract address, you’ll usually get input data that needs decoding. For ERC‑20 token transfers the function signature is transfer(address,uint256), which many block explorers decode into human-friendly fields automatically.
Gas fields deserve focused attention. There are three numbers people often confuse:
- Gas Limit — the maximum units of gas you allow for the transaction.
- Gas Used — the actual units consumed by execution.
- Gas Price / Max Fee / Max Priority Fee — how much you’re paying per unit.
After the London fork, EIP‑1559 changed how fees are expressed: there’s a base fee (burned) and a priority fee (miner tip). Wallets usually present a simplified view, but the explorer will show the full breakdown. That helps when you’re optimizing for speed vs. cost.
2) ERC‑20 tokens — common pitfalls and how to interpret events
ERC‑20 introduced a standard interface for tokens, and most explorers parse Transfer events so you can see token movements the same way you see ETH transfers. But—important—tokens are just smart contracts. That means:
- Token balances are contract state, not native ETH balances.
- Token transfers can fail silently if the contract implements unusual logic.
- Approvals (approve/transferFrom pattern) are separate transactions and can be exploited if not managed carefully.
When auditing token transfers, check both the transaction and the logs. The Transfer event typically includes indexed topics: from, to, value. Logs are cheaper on-chain and provide the canonical view of token movements. Also watch for transferFrom patterns that shift tokens without direct transfer calls from the token owner — that’s the common pattern for DEXs and contracts that operate on behalf of users.
3) Gas tracking — practical tips for developers and users
Gas estimation is heuristic. Wallets estimate gas based on simulating the transaction against the latest state, but state changes, mempool congestion, and network forks can alter outcomes. If a transaction underestimates gas, it can run out of gas and revert — you still pay the fee for attempted execution. So for safety, set a gas limit slightly higher than the estimate and a reasonable max fee.
Use gas trackers to see real-time fee suggestions and historical trends. The tracker will show low/average/high fee bands and the recent base fee trend per block. If you send a time-sensitive transaction (e.g., interacting with a DEX during an arb window), prioritize speed and set a competitive priority fee. For everyday transfers, lean towards the lower band during off-peak hours.
Pro tip for devs: when writing contracts or scripts that batch many operations, always measure gas usage in testnets first and add a margin. Gas optimizations at the opcode level can save real dollars across many users.
4) Common debugging steps when a transaction fails
When a tx fails or is stuck pending, follow a checklist:
- Confirm nonce sequencing. A stuck low‑nonce tx blocks later ones.
- Check gas price vs. current network demand. You may need to replace the tx with one at the same nonce and higher fee («speed up» or «replace by fee»).
- Read the revert reason. Many explorers and RPCs surface the revert string if the contract returns one.
- Inspect logs and internal transactions to see side effects and why a contract reverted.
If you can’t decode the revert, re-run the transaction locally against a node with debugging tools (like ganache or a full node’s debug_traceTransaction) to step through the EVM execution. That will tell you which opcode triggered the failure.
5) Security notes — approvals, malicious tokens, and phishing
Approvals are a persistent hazard. When you approve a contract to spend tokens, you’re granting ongoing permission until you revoke it. Attackers aim for approvals with large allowances. Regularly audit and revoke allowances for contracts you no longer use. Tools exist to help with this, and most explorers link to allowances on token pages.
Also be careful with token contracts that include backdoors (e.g., blacklist or transfer fees) — not all ERC‑20 tokens are created equal. Verify contract source code, check audits, and review community discussions before interacting with unknown tokens. And yes, double‑check contract addresses; scammers commonly deploy lookalike tokens with similar names.
6) Using block explorers effectively
A good explorer lets you:
- Search by address, transaction hash, or block number.
- View decoded contract interactions and event logs.
- Trace internal transactions and token transfers.
- See source code and contract ABI when verified.
When you need a trustworthy explorer, I often point people to reputable tools and resources that integrate those features. For a practical walkthrough of explorer pages and features, check this resource: https://sites.google.com/mywalletcryptous.com/etherscan-blockchain-explorer/
7) Workflow examples
Example — sending tokens to a contract:
1) Approve the contract for the exact token amount. 2) Call the contract’s function that performs transferFrom. 3) Monitor the tx; if gas suddenly spikes, pause further operations. This sequencing prevents over-approvals and reduces exposure.
Example — watching a DeFi position:
1) Monitor approval status and outstanding allowances. 2) Track pending withdrawals via internal tx or events. 3) Use gas tracker to schedule rebalance transactions when fees are low.
FAQ
How can I tell if a token transfer succeeded?
Check the transaction status (success/failure) and the token Transfer event in the logs. The event log is the most reliable indicator of token movement; if the Transfer event is present with the expected values, the transfer happened even if the contract called multiple internal functions.
Why is my transaction pending for so long?
Mostly because the gas price is too low relative to network demand, or because an earlier nonce is stuck. Either bump the fee by replacing the tx at the same nonce with higher gas, or cancel problematic earlier transactions.
What’s the easiest way to revoke token approvals?
Use a trusted tool or block explorer that exposes token allowances for your address, then submit a transaction to set allowance to zero for the contract you want to revoke. Watch gas fees when doing this — it costs ETH to revoke, but it’s often worth it for security.