agedu vs ccdu

agedu is a free, MIT-licensed Unix utility that scans directory trees and relates disk usage to file access times. It helps locate large data that has gone unused, but it cannot decide whether a file is safe to delete. It produces text and HTML reports, or can serve navigable HTML reports through a small built-in web server. In HTML reports, colours distinguish disused data in red from recently accessed data in green. Text reports can be limited to files not accessed within a chosen age, such as six months. Scan settings can cross filesystem boundaries and include, exclude, or prune files and directories. Results can be written as text on one machine and loaded into an index on another, including across different CPU architectures. Index files use restrictive permissions because they may reveal confidential filesystem information. By default, the built-in server uses Linux user-based access checks or HTTP Basic authentication with an invented password when those checks are unavailable. CGI mode has no access control of its own. There is no native Windows port, though a separate Windows scan utility can create a dump for loading into agedu on Unix.

ccdu has no write-up on Specifiction yet; its figures are above.