ZCrypto is a research and data collection cryptography library, designed to be used for measuring and analyzing cryptographic deployments on the Internet. It is largely centered around the WebPKI. ZCrypto contains forks of the Golang X.509 and TLS libraries that speak old TLS versions, deprecated ciphers. ZCrypto provides more lenient and open access to X.509 certificates and TLS handshake state than its standard library counterparts. ZCrypto also contains a custom X.509 chain builder, designed for bulk chain building across large sets of certificates.