I am the author of CryptoARM - most popular Russian software making/verifying digital signatures and making encrypted data.
CTjs (Official Web Site) - CTjs is a full set of classes necessary to work with any kind of Certificate Transparency log (V1 as from RFC6962, or V2 as from RFC6962-bis). In CTjs you could find all necessary validation/verification functions for all related data shipped with full-featured examples showning how to validate/verify. Also in scope of CTjs I made code showing example from RFC6962 item 2.1.3 on a real data from real Certificate Transparency log.
CAdESjs - CAdESjs is a specialized library making CAdES signatures by any level, up to LTA.
ByteStreamjs - ByteStreamjs is a set of classes manipulating with bytes and bits inside ArrayBuffer.
PAdESjs - (private repository at the moment, to be published soon). PAdESjs is a full-featured PDF parser and maker. With the library you could parse and make/modify any PDF file, with no restrictions, and could apply any PDF features, even from PDF 2.0 standard. Has PDF encryption/decryption functionality (password-based and certificate-based) and PDF signing functionality (all PAdES levels up to LTV).
pvutils - set of common routines for all repositories in PeculiarVenturies organization.