BitcoinKeychains

Cryptographically Awesome Keychains and Keyrings

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PassGuardian

Store and share your secrets safely by splitting them into cryptographically-secure pieces. To reconstruct the original, combine a specific number of these pieces. It's simple, secure, and free.

Coinometrics

Strength Ranking. A real-time measurement of the 51% attack cost. This cost is compared against defense spending across all countries.