Vuex
Official state management library for Vue 2 + 3 — Flux-inspired (state, mutations, actions, getters). Replaced by Pinia in 2022 as the official recommendation.
Evan You created Vuex in 2015. Pinia (created 2019 by Eduardo San Martin Morote, more type-safe, simpler API) became the official choice as Vue 3 matured. Vuex 4 still supports Vue 3 but receives no new development. Pattern: all mutations go through a central store ⇒ predictable state. Vue Devtools replays the mutations (time-travel debugging).