Whoa!
I’ve stared at transaction logs at 2 a.m. and thought: this is wild.
At first glance ERC-20 tokens feel simple—transfer, approve, balanceOf—repeat.
But digging in with a block explorer often reveals a messy, human-driven reality with failed transfers, nonce collisions, and tokens that quietly cost more than you expected.
My instinct said « it’s just decimals and allowances », though actually, wait—there’s more under the hood that trips both users and developers alike.

Here’s the thing.
When you send ETH or an ERC-20 token you expect a tidy confirmation.
Sometimes you get that.
Often you don’t.
Something felt off about how frequently the apparent simplicity dissolves into confusion—gas spikes, reorg worries, and contracts that behave differently than docs promised.

Okay, so check this out—I’ve been using explorers to trace bugs, confirm drops, and audit token flows.
Initially I thought a basic tx hash lookup would solve most questions, but then realized you need to triangulate data: internal transactions, event logs, contract creation traces, and the account’s nonce history.
On one hand the chain is transparent; on the other hand the raw transparency is noisy and requires context, which is why tools and a bit of pattern recognition matter.
I’m biased toward practical tooling, not hand-waving theory, but some habits are worth repeating because they save time—and money.

Short tip: always check the token decimals before trusting balances.
Seriously? Yes.
Many wallets show rounded balances.
A token with 18 decimals looks the same as one with 8 until you look at the contract.
That tiny difference makes people think they’ve got more tokens than they actually do, or they underpay gas because a UI misrepresents units.

How to read a transaction like a human (not like a naive script)

Start with the hash.
Then: what type of transaction is it?
A plain ETH transfer? A token transfer via transfer()/transferFrom()? A contract call that emits Transfer events?
The obvious path is to look at status and gasUsed.
If the status is 0 the tx failed.
But many people stop there.
Don’t.
Failed txs can still consume lots of gas and leave odd nonce gaps.

On explorers you’ll often see a separate « Internal Txns » tab.
These are not magic.
They’re message calls and value transfers triggered by contract code during execution.
Initially I ignored them.
Big mistake.
For example, a token swap contract might call several internal transfers to route funds across pools, and only the top-level tx tells the whole story.
If you’re tracing stolen funds, those internals are gold.

There’s also the matter of events.
Event logs are how ERC-20 emissions signal transfers and approvals.
But here’s a quirk: events are not authoritative state; the token contract’s storage is.
Events are convenient indexes.
That means a token might emit a Transfer event while actually reverting changes to storage in edge cases, or a poorly implemented contract could emit non-standard events, which confuses parsers and human auditors alike.

Gas — oh gas — this part bugs me.
The market price for gas is volatile.
A tx that succeeded yesterday may fail today at the same gas price.
Now, there are heuristics: look at baseFee, maxFeePerGas, and maxPriorityFeePerGas.
But if you want reproducible behavior, replays in a local fork can help recreate the execution environment and confirm why a call burned through more gas than expected.

Let’s talk allowances and approvals.
Approvals are a permission model that grants contracts the right to move your tokens.
It’s simple until you inherit a token that uses non-standard allowance behavior or a dApp that requires infinite approvals.
My advice: be wary of infinite approvals unless you trust the contract and have a plan to revoke.
Pro tip: revoke in a separate tx once your operation succeeds; that avoids tying revocation gas to your primary flow and gives you a clear rollback point.

Nonce management deserves a paragraph of its own.
Nonces ensure ordering.
If you broadcast two txs with the same nonce, only one will be mined.
On one project I worked on we hit a stuck nonce after a wallet retry mechanism resent a tx; it created a small outage until we manually replaced the stale tx.
So keep an eye on pending pools and don’t automatically retry without checking the latest nonce state on the chain.

Alright, a quick workflow I use when something looks off:

• Grab the tx hash.
• Check status, gasUsed, and logs.
• Open internal transactions and trace value movements.
• Inspect events and then the contract’s relevant storage slots if needed.
• Replay on a fork if the reason for failure isn’t obvious.

If you want a fast, reliable place to do step one through three, I’ve often started with a trusted explorer—especially when I’m dealing with ERC-20 quirks—like the etherscan blockchain explorer because it exposes both logs and internals cleanly and is widely referenced across tooling.
I’m not advertising; I’m saying it’s practical.
And yeah, there’s a learning curve even with good tooling, because sometimes the UI hides a nuance you’re about to trip on.

Common puzzles and how to solve them

Problem: You sent tokens, tx shows success, but balance didn’t update.
Answer: Check which token contract you’re looking at, confirm decimals, and verify the recipient actually implemented a token fallback if it’s a contract.
Sometimes the token was sent to a contract without an ERC-20-compatible receive handler and the token is effectively stuck.

Problem: Wallet shows pending tx that never mines.
Answer: Check the network’s baseFee and your maxFeePerGas.
If you’re below the active threshold, replace the tx with a higher fee using the same nonce.
Also check for mempool saturation—during big market events the mempool fills fast, and replace-by-fee is your friend.

Problem: Confusing internal transfers that look like money appeared from nowhere.
Answer: Follow the chain of internal txns and logs.
A contract might distribute rewards in tiny fragments across many addresses, and only by walking the call graph do you see the origin.
Be patient.
It takes practice.