Crypto404 is a free blockchain address security scanner that checks wallet addresses for scams, sanctions, and security risks across 21+ blockchains. Enter any crypto address and get an instant risk assessment based on multiple threat intelligence sources.

Yes, Crypto404 is completely free for individual use. You can scan unlimited addresses through our web interface. We also offer an API for developers with rate limits on the free tier and higher limits for enterprise users.

We support 21+ blockchains including Bitcoin, Ethereum, Solana, Cardano, Polkadot, Cosmos, Tron, XRP, Litecoin, Dogecoin, Avalanche, Monero, Zcash, Polygon, BNB Chain, Arbitrum, Optimism, Base, zkSync, Osmosis, Celestia, and Injective. We are continuously adding support for more chains.

Our OFAC SDN list is cached for 24 hours and sourced from the official U.S. Treasury data. Community reports are reviewed daily by our team. ChainAbuse data is queried in real-time during each scan, ensuring you always get the latest threat intelligence.

Yes, all key derivation happens locally in your browser using JavaScript. Your private keys and seed phrases are never sent to our servers. We use established cryptographic libraries such as ethers.js and @solana/web3.js for client-side derivation, so your sensitive data never leaves your device.

We store scan results (address and risk level) for caching and analytics purposes. We never store private keys or seed phrases. IP addresses are hashed for rate limiting, not stored in raw form. Your privacy is a top priority.

No. Crypto404 only scans public addresses. The private key derivation feature runs entirely in your browser. Our servers never receive your keys or seed phrases. We physically cannot access your funds. You can verify this by inspecting our open-source code or monitoring network requests.

Safe: no issues found across any of our databases. Low: minor pattern flags that are likely benign. Medium: some community reports or suspicious on-chain patterns detected. High: confirmed reports from trusted sources or interaction with known mixer contracts. Critical: address is on the OFAC sanctions list or is a confirmed scam address.

We check multiple databases and apply various heuristics, but no scanner is 100% accurate. A "safe" result does not guarantee an address is trustworthy, and a flagged result does not necessarily mean an address is malicious. Always do your own research (DYOR) before transacting with any address.

The OFAC SDN (Specially Designated Nationals) list is maintained by the U.S. Treasury Department's Office of Foreign Assets Control. It includes sanctioned individuals, entities, and crypto wallet addresses. Interacting with addresses on this list may violate U.S. law and could result in legal consequences.

ChainAbuse is a crowdsourced platform where users report scam, phishing, and fraud cryptocurrency addresses. During scans, we optionally query the ChainAbuse database to check if an address has been reported by the community, providing an additional layer of threat intelligence.

An address may be flagged for several reasons: it appears on the OFAC sanctions list, it has community reports filed against it, pattern analysis detected suspicious behavior (e.g., known mixer contracts, burn addresses), or it was reported on ChainAbuse. Check the flagged issues section in your scan results for specific details about why the address was flagged.

The batch scanner lets you scan up to 50 addresses at once on the same blockchain. Simply paste multiple addresses separated by new lines and scan them all in one go. This is useful for checking a large number of addresses quickly, such as when auditing a set of counterparty wallets.

The watchlist lets you save addresses you want to monitor over time. All watchlist data is stored locally in your browser, so nothing is sent to our servers. You can re-scan any watched address at any time to check for newly reported threats or changes in risk status.

Yes! Visit the Report page to submit information about a suspicious address. Provide the address, the blockchain it belongs to, a description of the suspicious activity, and any supporting evidence. Your report will be reviewed by our team, and if confirmed, it will be added to our database to help protect other users.

Yes, we offer a REST API for developers who want to integrate Crypto404 address scanning into their own applications. Visit our API Documentation page for full details, including endpoints, request formats, and response schemas. The free tier includes rate limits, with higher limits available for enterprise users.