CitreaScan

# Frequently Asked Questions

# About Citrea & CitreaScan

# What is Citrea?

Citrea is Bitcoin's first ZK Rollup - a layer 2 blockchain that settles on Bitcoin. It uses zero-knowledge proofs to process transactions off-chain and verify them on Bitcoin, combining Bitcoin's security with Ethereum's smart contract capabilities through full EVM compatibility.

# What is CitreaScan?

CitreaScan is the dedicated blockchain explorer for Citrea Testnet, powered by Blockscout. It provides a comprehensive interface for exploring transactions, blocks, addresses, and smart contracts on the Citrea network.

# Is CitreaScan free to use?

Yes, CitreaScan is completely free to use. Anyone can access the explorer to view blockchain data, search transactions, and interact with smart contracts.

# What is Blockscout?

Blockscout is the #1 open-source blockchain explorer that powers CitreaScan. It provides proven reliability, comprehensive features, and extensive API support for blockchain exploration.

# Using CitreaScan

# How do I search for a transaction?

Paste the complete transaction hash (66 characters starting with 0x) into the search bar. The transaction details page will show status, gas fees, addresses involved, and more.

# How can I view my wallet balance?

Enter your wallet address (42 characters starting with 0x) in the search bar. You'll see your balance, transaction history, token holdings (ERC-20, ERC-721, ERC-1155), and internal transactions.

# Why is my transaction showing as pending?

A pending status means your transaction has been broadcast but hasn't been included in a block yet. This typically takes seconds to minutes depending on:

  • Network congestion
  • Gas price you set
  • Transaction complexity

# How do I check if my transaction succeeded?

Look for the status indicator:

  • ✅ Green checkmark = Success
  • ❌ Red X = Failed/Reverted
  • ⏳ Clock = Pending

Failed transactions still consume gas for the computation attempted.

# Understanding Citrea

# How does Citrea differ from other L2s?

Citrea is unique because it:

  • Settles on Bitcoin (not Ethereum)
  • Uses zero-knowledge proofs for security
  • Provides full EVM compatibility on Bitcoin
  • Is the first zkEVM rollup on Bitcoin

# Is Citrea Testnet safe to use?

Citrea Testnet is for testing purposes only. Do not use real assets or production applications on testnet. Use it to:

  • Test smart contracts
  • Develop and debug dApps
  • Experiment with transactions
  • Learn about the network

# What is a zkEVM?

A zkEVM (Zero-Knowledge Ethereum Virtual Machine) is a virtual machine that executes smart contracts while generating zero-knowledge proofs. This allows Citrea to verify transactions on Bitcoin without revealing all transaction details, combining privacy with security.

# Smart Contracts

# How do I verify a smart contract?

  1. Navigate to your contract address on CitreaScan
  2. Click on the "Contract" tab
  3. Select "Verify & Publish"
  4. Enter your source code, compiler version, and optimization settings
  5. Submit for verification

Verified contracts display their source code and allow direct interaction.

# Can I interact with contracts on CitreaScan?

Yes! For verified contracts:

  • Read Contract: Query public functions and state variables (no wallet needed)
  • Write Contract: Execute state-changing functions (requires wallet connection)

# What wallets work with CitreaScan?

CitreaScan supports standard Web3 wallets:

  • MetaMask
  • WalletConnect
  • Coinbase Wallet
  • Other EVM-compatible wallets

# Technical Questions

# How often is the data updated?

CitreaScan updates in real-time as new blocks are added to the Citrea blockchain. Block times on Citrea Testnet are typically a few seconds.

# Can I use CitreaScan to send transactions?

No, CitreaScan is a read-only explorer. To send transactions:

  1. Use a Web3 wallet (MetaMask, etc.)
  2. Connect to Citrea network
  3. Send transactions through your wallet
  4. Track them on CitreaScan

# What is gas on Citrea?

Gas is the unit measuring computational effort required to execute operations. Similar to Ethereum:

  • Gas Limit: Maximum gas you're willing to spend
  • Gas Price: Amount you pay per gas unit
  • Transaction Fee: Gas Used × Gas Price

# Can I access historical data?

Yes, CitreaScan provides complete blockchain history from genesis block to present. Search any historical transaction, block, or address.

# Does CitreaScan have an API?

Yes! CitreaScan provides:

  • REST API: Standard HTTP endpoints for blockchain data
  • GraphQL API: Flexible query interface
  • WebSocket: Real-time event subscriptions

Visit the API documentation for details and endpoints.

# Tokens & NFTs

# How do I find my tokens on CitreaScan?

Search for your address, then check the "Tokens" tab to see:

  • ERC-20 token balances
  • ERC-721 NFTs
  • ERC-1155 multi-tokens

# What is token approval?

Token approval allows smart contracts to spend tokens on your behalf. Check your "Token Approvals" to see which contracts have spending permissions - important for security.

# Can I see NFT metadata?

Yes, for ERC-721 and ERC-1155 tokens, CitreaScan displays:

  • Token ID
  • Metadata (if available)
  • Owner history
  • Transfer events

# Troubleshooting

# Why can't I find my transaction?

Possible reasons:

  • Transaction is still pending (wait a few moments)
  • Wrong network (ensure you're on Citrea Testnet)
  • Incorrect transaction hash (verify the hash)
  • Transaction failed to broadcast (check your wallet)

# What does "out of gas" mean?

Your transaction ran out of gas before completing. Increase the gas limit when retrying. The consumed gas is still charged.

# Why is my contract interaction failing?

Common causes:

  • Insufficient gas limit
  • Function requirements not met (e.g., insufficient balance)
  • Contract logic rejection
  • Incorrect function parameters

Check the error message in the transaction details for specifics.

# Support & Resources

# Where can I get help?

# How do I report a bug?

Submit bug reports through our GitHub Issues (opens new window) page with:

  • Detailed description
  • Steps to reproduce
  • Expected vs actual behavior
  • Screenshots if applicable

# Is CitreaScan open source?

Yes, CitreaScan is built on Blockscout, which is open source. The repositories are:

  • CitreaScan/blockscout - Explorer backend
  • CitreaScan/frontend - Frontend application
  • CitreaScan/blockscout-rs - Rust microservices

# Where can I learn more about Citrea?

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