Web3Signer
Open-source signing service written in Java.
Web3Signer is an open-source signing service developed under the Apache 2.0 license and written in Java. EthSigner is capable of signing on multiple platforms using private keys stored in an external vault, or encrypted on a disk.
Web3Signer can sign payloads using secp256k1 and BLS12-381 signing keys, and supports the following platforms: Ethereum 1.0, Ethereum 2.0, Filecoin.