KFile-Cert is a kfile-plugin for KDE. It offers detailed information on X.509 certificate files, which often have extensions .cer, .crt, or .pem. The information is displayed in the file properties dialog box, Konqueror pop-up file tips, and in Konqueror info list view. The information includes certificate subject, issuer, validity term, and status.
PeaZip is a cross-platform file archiver utility that provides a unified portable GUI for many open source technologies like 7-Zip, FreeArc, PAQ, UPX, etc. Creates 7Z, ARC, BZ2, GZ, *PAQ, PEA, QUAD/BALZ, TAR, UPX, WIM, XZ, and ZIP files. It extracts more than 150 archive types: ACE, ARJ, CAB, DMG, ISO, LHA, RAR, UDF, ZIPX, and more. Features of PeaZip include extracting, creating, and converting multiple archives at once, creating self-extracting archives, split/join files, strong encryption with two factor authentication, an encrypted password manager, secure deletion, find duplicate files, calculate hashes, and export job definitions as scripts.