Amethyst is the flagship native Android Nostr client written in Kotlin that delivers a full-featured social experience—posts, replies, reactions, long-form articles, live streams, and zap receipts—while keeping private keys on-device and never asking for an email or password. Users generate or import a 12-word seed, choose default relays, and instantly browse global or tailored feeds powered by customizable filters (kind-3 follows, hashtags, lists, gift wraps). Built-in Lightning wallets (with lnurl-pay, lud-16, and webln support) allow one-tap zaps in sats or fiat; the wallet runs over Tor by default and can connect to self-hosted LND, CLN, or a custodial service. Features include offline draft storage, relay switcher with latency scores, mute lists, spam filters, NIP-05 verification badges, and animated media galleries. Entire codebase is GPL-3.0 and published on GitHub, enabling reproducible builds via F-Droid and Google Play; developers can add new NIPs through a clean plugin architecture while users keep full ownership of their identity and data.