`gau` (getallurls) is a high-performance Go CLI tool that aggregates known URLs for a given domain from multiple public web archives: Wayback Machine, CommonCrawl, AlienVault OTX, and URLScan. It is designed primarily for security researchers and penetration testers to enumerate URL endpoints, supporting concurrent fetches, filtering by status code/mime-type/date, blacklisting extensions, and deduplication of parameters. The architecture follows a clean provider interface pattern, with each data source implemented as a separate package satisfying a common `Provider` interface. The runner orchestrates a worker pool for concurrent processing, and output is handled via configurable JSON or plain text writers. The codebase is well-structured, testable in principle (though no tests are present in the visible tree), and the dependency graph is minimal and modern, relying on `fasthttp` for efficient HTTP requests and `viper` for configuration management.