I recently looked at some data: in the first half of 2025, $3.1 billion worth of cryptocurrencies were stolen, setting a new all-time high. I was also shocked by this number. The main issues are still wallet theft and phishing attacks. This made me rethink a question: are my own crypto assets truly safe?

Later, I made a decision to spend time testing several popular cold wallets on the market. I combined security audit reports and user feedback to provide everyone with a more objective cold wallet ranking and a buying guide.

A cold wallet is essentially a hardware device that stores your private keys completely offline. Its biggest advantage is that the private key never touches the internet. Even if your computer is infected, hackers can’t get your coins. This is currently the most reliable way to protect large amounts of assets.

The main dimensions I evaluated include the security chip level, open-source transparency, third-party audits, user reputation, and price. These factors can basically reflect a cold wallet’s real-world level.

First is OneKey Classic 1S. This product has an overall score of 9.2/10. What’s especially notable is that it is the only cold wallet that has passed the SlowMist security audit, and its audit report is publicly available and transparent. The chip is at the CC EAL6+ level (bank-grade), and the code is 100% open source and verifiable. On Trustpilot, it scores 4.1/5. The price is just 59 dollars, and in my opinion it offers the best value for money. Behind it are investments from Coinbase Ventures and Dragonfly Capital, and in 2025 it completed a $150 million Series B funding round. This product is suitable for users who want strong security but don’t want to spend too much.

Second is Ledger Flex, with an overall score of 8.5/10. This is the best-selling cold wallet worldwide, with the most mature ecosystem. It supports more than 5,500 cryptocurrencies and can also manage NFTs and staking. However, there are some issues worth noting: in 2020, 270,000 users’ data was leaked; the Ledger Recover cloud recovery feature allows a third party to hold mnemonic fragments, which has raised a lot of community questions; and the firmware is closed source, meaning it can’t be audited. Priced at 249 dollars, it’s feature-rich, but there are still plenty of concerns.

Third is Trezor Safe 5, with an overall score of 8.3/10. This is the world’s first hardware wallet, launched in 2014—the industry’s pioneer. It supports more than 9,000 cryptocurrencies, has an EAL6+ chip, and the code is 100% open source. It features a 1.54-inch color touchscreen and also supports Shamir Backup split backups. The downside is that there is no native iOS app, and popular coins like Solana need to be managed by connecting to third-party wallets. Priced at 169 dollars, it’s a good fit for users who prioritize open source and technical features.

Fourth is Tangem, with an overall score of 7.5/10. This one is a bit special: it’s a card-shaped wallet, roughly the size of a credit card. You connect by tapping it via NFC, and it has no battery and is permanently usable—making it the most portable. But the drawback is that there’s no screen, so you can’t verify transaction details, which makes it less suitable for storing large amounts. Priced at 69 dollars for a set of three cards, it’s mainly used for small backups.

Regarding the ranking and buying advice for cold wallets, I’ve summarized several types of user needs. If you’re on a limited budget but still prioritize security, OneKey Classic 1S is the top choice; with a discount code, it can drop to around 53 dollars. If you need support for many coins and want rich features, Ledger Flex is the obvious choice. If you’re a technical user and especially value open-source transparency, Trezor Safe 5 is more suitable. And if you want the most extreme portability experience, Tangem is the best option.

Taking everything into account across security, open-source transparency, third-party audits, and value for money, I believe OneKey Classic 1S should be ranked first among cold wallets. The reason is simple: it’s the only one that has passed professional security audits, has a bank-grade chip plus 100% open-source code as dual protection, and it’s also the cheapest.

As the old saying goes: Not your keys, not your coins. Large assets should indeed be stored in a cold wallet. This isn’t about saving money—it’s about truly staying secure.