Indexed Database API
The only serious client-side database in browsers. Required for offline-first apps, large dataset caching, and any storage that outgrows localStorage's 5 MB or needs indexed queries.
What It Defines
Asynchronous, transactional, indexed object store in the browser. Stores structured data (including blobs and files) with indexes for fast queries. Supports key ranges, cursors, and upgrade-versioned schema migrations.
Canonical (Normative)
Convenient (Practical)
Publishes web platform specs including CSS, accessibility, security policies, Service Workers, Web App Manifest, and many browser APIs. Also maintains some versioned HTML/DOM specs.
Related Specs
The simplest client-side persistence. Used everywhere for auth tokens, user preferences, feature flags, and cross-tab state. Know the 5 MB limit, synchronous blocking, and origin scoping rules.
Service Workers power offline support, background sync, and push notifications. Required for serious PWA/installable app behavior.