Ever had that moment where you want to trace a token transfer and you can’t remember which wallet did what? Yeah, me too. It’s oddly satisfying when a trail comes together. Short answer: you need tools. Longer answer: you need the right habits and a little patience.

Explorers are the single-pane-of-glass for on-chain investigation. They show transfers, contract calls, confirmations, gas spent, and sometimes human-readable metadata — if the contract author bothered. They’re not perfect. They rarely explain intent. But they do provide the receipts. And when something smells off, you can usually see why.

Why this matters: NFTs are pieces of on-chain state tied to ERC-721 or ERC-1155 standards, but most NFT ecosystems still interoperate with ERC-20 tokens and plain ETH. Tracking those flows helps you verify provenance, detect rug pulls, and debug marketplace integrations. Oh, and it’s useful for gas budgeting too.

What an NFT explorer shows (and what it doesn’t)

At a glance, an NFT-focused explorer will show token IDs, ownership history, mint events, and sometimes metadata URIs. It will also show the underlying transaction hash, block number, and the input data that triggered the contract call. That input data is where the story usually lives.

But here’s the thing. Metadata often points off-chain. So an NFT could have on-chain provenance but an off-chain image URL that disappears. That matters if you’re auditing long-term value. My instinct has been to check the metadata host — IPFS is easier to trust than a random CDN.

Explorers rarely provide narrative. They give evidence. You interpret it. Sometimes you misread it. Then you re-check. And okay, sometimes you just follow the breadcrumbs like a detective.

Key transaction elements to inspect

Transaction hash. That’s your primary key. Click it. Copy it. Use it in APIs if you need to automate.

Block number and timestamp. Blocks anchor events in time. If you correlate with off-chain events — a contract upgrade, a marketplace outage — these can explain anomalies.

From and to addresses. Simple, but powerful. When a „to“ address is a contract, you should inspect the contract creation or verify its source (if available).

Value and token transfers. ETH moved? Token transfers? Token approvals? Each is a different risk vector. Approvals can leave permissions standing indefinitely if the user doesn’t revoke them. That part bugs me — very very important to check approvals.

Input data / decoded logs. This is where you see function signatures like safeTransferFrom, mint, or approve. If the explorer decodes the input, use that. If not, paste the input into an ABI decoder.

ERC-20 tokens and NFTs: the interplay

Most NFT marketplaces accept ETH or ERC-20 tokens for payment. That means when you analyze a trade you might see both an ERC-20 transfer and a separate NFT transfer within the same transaction or in back-to-back transactions. Look for the following pattern: payment token approval → payment transfer → NFT transfer. If anything deviates, pause.

On one hand, I’ve seen clean sequences that match the marketplace flow. On the other hand, there are weird batched transfers where a middleman contract re-routes funds. Initially I thought such batching was always malicious, but then I realized—nope—sometimes it’s a gas optimization or an aggregator doing its job.

Check token contracts for standard behavior. Does the ERC-20 implement allowances correctly? Does the NFT contract follow ERC-721’s events? Contracts can deviate or extend standards, so don’t assume compliance unless you verify.

Practical steps: walk-through for a suspicious NFT transfer

1. Start with the transaction hash. Look at the inputs, logs, and event list. Decode the input if needed.

2. Inspect „from“ and „to.“ Are these EOAs (externally owned accounts) or contracts? If it’s a contract, check the contract creation tx and the verified source code (if available).

3. Check approvals. Did the seller give blanket approval to a marketplace contract? If so, that could be a long-term exposure. You can tell by looking for approve or setApprovalForAll events.

4. Verify the metadata. Follow the tokenURI. Is it IPFS? HTTP? Does the content match what’s advertised? (oh, and by the way… sometimes tokenURI is a pointer to an API that changes responses.)

5. Cross-check payment flows. Did an ERC-20 transfer occur from buyer to marketplace, and then a payout to seller? Or did funds route through a third address? Follow the money, literally.

6. Look at the gas. High gas might indicate a failed or retried call, or it might mean complex on-chain logic executed. That often explains higher marketplace fees.

Using an explorer programmatically

Manual inspection is one thing. Automating checks is another. Most explorers offer APIs to query transactions, internal transactions, and logs. If you’re building tooling or monitoring several wallets, set up webhooks or a cron job to poll for events tied to addresses you care about.

Watch for these events programmatically:

• Transfer (ERC-20 and ERC-721)
• Approval and ApprovalForAll
• OwnershipTransferred or Upgrade events (for upgradeable proxies)

Also, track contract verification status. A verified contract with source code is much easier to trust than an opaque bytecode blob. That doesn’t guarantee safety, but it reduces unknowns.

Tips and habits for daily use

Bookmark vendor contracts you trust. Keep a short list of known marketplace and bridge contracts so you can quickly recognize them in transactions. That saves time.

When you find a suspicious transfer, document it. Save the tx hashes and a short note. If you’re rolling this into a security process, stamps of evidence matter.

Use naming features if your explorer supports them. Label recurring addresses. It’s a small usability win that compounds quickly.

Revoke approvals regularly. Seriously. Wallets like MetaMask and others now show token approvals, and you can revoke them. My gut says do that monthly if you’re actively trading.

Where to go next — tools and learning resources

If you want a single place to start poking at everything — tokens, NFTs, and transactions — try a robust explorer that decodes contracts and logs (I often start with explorers that make it easy to jump from tx to token to holder list). You can also use the API to build lightweight monitors for wallets or collections. For quick reference, check this link to an ethereum explorer that aggregates many of these views in one place.

Learn how to read ABI-decoded logs. Once you can parse a function signature (0x…), a lot opens up. There are simple libraries for decoding ABI inputs in JavaScript, Python, and Rust.