A block explorer is your window into the Cardano blockchain. Think of it like a bank statement for the entire network—except instead of just your transactions, you can see every block, every transaction, and every address on the chain. This guide teaches you how to read that data so you can verify payments, track your ADA, and understand what's happening on-chain.
What is a Cardano Block Explorer?
A block explorer is a search engine for the blockchain. It takes the raw data stored across thousands of nodes and presents it in a human-readable interface. When you send ADA, mint a token, or delegate to a stake pool, that action gets recorded in a block. The explorer lets you look up that block, the transaction inside it, and the addresses involved.
Analogy: If the blockchain is a public ledger book, the block explorer is the reading glasses that let you make sense of the entries. You don't need to run a node or understand code—just type a transaction hash, address, or block number into the search bar.
Popular Cardano explorers include CardanoScan, CExplorer.io, and PoolTool. They all show the same on-chain data but with different interfaces. This guide uses CardanoScan as the reference, but the concepts apply everywhere.
[Visual: Diagram - Anatomy of a Cardano Block]
Key Components of the Explorer Interface
The Search Bar
The search bar is your entry point. You can paste:
- Transaction Hash (TxID) — a 64-character string like
a1b2c3...that uniquely identifies one transaction - Address — your wallet's public address (starts with
addr1...for mainnet) - Block Height — the sequential number of a block (e.g.,
10,500,000) - Stake Pool ID — starts with
pool1...to look up pool performance - Policy ID — for native tokens and NFTs (starts with a hex string)
Network Overview Dashboard
Before diving into specifics, the homepage shows network vitals:
- Current Block Height — the latest block number. Increases every ~20 seconds.
- Current Epoch & Slot — Cardano's timekeeping system (explained below).
- TPS (Transactions Per Second) — real-time network throughput.
- Active Stake — total ADA delegated to pools.
- Latest Blocks List — a feed of the most recent blocks with producer, time, and transaction count.
[Visual: Flowchart - Navigating the Explorer Interface]
Deciphering Block Data
When you click a block (from the latest blocks list or by searching its height), you see its anatomy. Here's what each field means.
Block Height
The sequential number of this block in the chain. Block 1 was the genesis block. Each new block increments by 1. Think of it as the page number in the ledger book.
Slot & Epoch — The Blockchain Calendar
Cardano divides time into epochs (5 days each) and slots (1 second each). There are 432,000 slots per epoch (5 days × 24 hours × 60 minutes × 60 seconds).
- Epoch = the "week" (e.g., Epoch 450)
- Slot = the "minute" within that week (e.g., Slot 215,000 of 432,000)
A block's slot tells you exactly when it was minted. Slot 0 of an epoch is the epoch boundary. This matters for staking rewards—rewards are calculated per epoch and distributed at the next epoch boundary.
Block Producer (Stake Pool)
The stake pool that minted this block. Shows the pool's ticker (e.g., [PIZZA]) and pool ID. In Ouroboros Proof of Stake, slots are randomly assigned to pools proportional to their stake. Seeing which pool produced a block lets you verify your pool is performing.
Transactions Count
How many transactions are packed into this block. A block can hold many transactions. Higher count = more network activity. Empty blocks (0 txs) happen when a slot leader produces a block but no transactions were waiting—rare on mainnet.
Block Size & Fees
- Size — in bytes. Larger blocks = more data = more fees collected.
- Total Fees — sum of all transaction fees in this block. Goes to the block producer (pool) and the treasury.
Previous/Next Block Hash
Cryptographic links chaining blocks together. The previous hash points to the parent block; the next hash will point to this block once the next one is minted. This is what makes the chain immutable—changing one block breaks all subsequent hashes.
[Visual: Diagram - Block Header Fields Explained]
Understanding Transaction Details
Click a transaction hash from the block view or search it directly. This is where most users spend their time.
Transaction Hash (TxID)
The unique fingerprint. SHA-256 hash of the transaction body. This is your receipt. Share it to prove a payment was sent. It looks like: 3a7f9e2b... (64 hex characters).
Inputs & Outputs — The UTXO Model
This is the most important and most confusing part for newcomers.
Cardano uses eUTXO (Extended Unspent Transaction Output). Unlike Ethereum's account model (where your balance is a single number), your ADA lives in discrete "chunks" called UTXOs. Each UTXO has an address and an amount.
When you send ADA:
- Inputs — Your wallet selects one or more UTXOs you control that sum to ≥ the amount you're sending + fees.
- Outputs — The transaction creates new UTXOs:
- Recipient output — The amount sent to the destination address.
- Change output — The remainder goes back to your own address (often a new change address for privacy).
Example: You have a 100 ADA UTXO. You send 5 ADA to a friend. Fee = 0.17 ADA.
- Input: 100 ADA (your UTXO)
- Output 1: 5 ADA → friend's address
- Output 2: 94.83 ADA → your change address
- Total outputs = 99.83 ADA (100 - 0.17 fee)
Key insight: Seeing two outputs when you only sent to one person is normal. The second output is your change. Don't panic—it's not a second payment.
[Visual: Flowchart - Following a Transaction from Input to Output]
Fees
Every transaction pays a fee. Cardano's minimum fee formula: fee = a + b × size
a= 0.155381 ADA (constant)b= 0.000043946 ADA/bytesize= transaction size in bytes
Typical simple transfer: ~0.17–0.20 ADA. Complex transactions (multiple tokens, smart contracts) cost more. Fees go to the stake pool that mints the block (and a portion to the treasury).
Confirmation Status
- Pending — Transaction submitted to mempool, waiting for a slot leader to include it in a block.
- Confirmed — Included in a block. But wait: On Cardano, "confirmed" usually means 1 block deep. For high-value transactions, wait for more blocks (more confirmations = more finality).
- Failed — Rejected (insufficient funds, script failure, etc.). The fee is still paid.
Metadata (Optional)
Transactions can carry metadata (key-value pairs). Used for:
- NFT metadata (CIP-25)
- Messages/memos
- Smart contract data
- Catalyst voting receipts
Click "Show Metadata" to see it. Not all explorers display this by default.
Practical Use Cases
Verifying a Received Payment
- Get the TxID from the sender.
- Paste into explorer search.
- Check:
- Status: Confirmed (green checkmark)
- Outputs: Your address appears with the correct amount
- Confirmations: At least 1 (more for large amounts)
- Done. The ADA is in your wallet.
Checking Your Wallet's History
- Paste your wallet address (not stake address) into search.
- View the Transactions tab.
- See all incoming/outgoing txs with dates, amounts, and statuses.
- Click any TxID for details.
Pro tip: Use the "Export CSV" feature (if available) for tax records.
Monitoring a Stake Pool's Activity
- Search your pool ID (or pool ticker).
- Check the Blocks tab.
- Look for:
- Blocks minted this epoch — should match the pool's expected slots based on stake.
- Missed blocks — slots assigned but no block produced (downtime).
- Block height links — click to verify the block exists and has transactions.
- Compare with PoolTool or Adapools for historical performance.
[Visual: Diagram - Stake Pool Block Production Dashboard]
FAQ
Is a block explorer private?
No. All data is public. Anyone who knows your address can see your balance and transaction history. This is a feature, not a bug—it's what makes the blockchain transparent. For privacy, use a new address for each transaction (most wallets do this automatically via change addresses).
Why is my transaction not appearing yet?
- Mempool congestion — Many transactions competing for limited block space. Wait a few minutes.
- Low fee — If you manually set a fee below minimum, it won't be included. Use wallet defaults.
- Wallet not broadcasting — Some light wallets delay submission. Force refresh or reopen.
- Network issue — Rare. Check CardanoScan's status page or Twitter.
Which Cardano explorer is the best?
- CardanoScan — Best all-rounder, clean UI, good API.
- CExplorer.io — Excellent for stake pool operators, detailed epoch data.
- PoolTool — Best for pool performance analytics.
- Koios/Blockfrost — Developer-focused APIs (not human UIs).
Use multiple. They all read the same chain.
What does "unspent" mean in UTXO?
A UTXO is "unspent" until it's used as an input in a new transaction. Once spent, it's gone—consumed—and new UTXOs are created as outputs. Your wallet balance = sum of all UTXOs you control that are still unspent.
Can I cancel a pending transaction?
No. Once broadcast, you cannot cancel. You can try a "replace-by-fee" (submit a new tx with higher fee using same inputs), but not all wallets support this. Best prevention: double-check before sending.
This guide covers the essentials. For deeper technical details, see the Cardano Developer Portal and the Ouroboros protocol papers.