Storage Buckets API: named partitions

In one line: navigator.storageBuckets lets a page open multiple, separately named storage buckets with independent eviction policies. The proposal includes per-bucket IndexedDB and CacheStorage, while Chrome’s documented implementation currently supports only IndexedDB.

Opening a bucket

Per Chrome’s guide, navigator.storageBuckets.open(name, options) creates or opens a bucket by name and returns a StorageBucket:

function openIndexedDB(idbFactory, name, version) {
  return new Promise((resolve, reject) => {
    const request = idbFactory.open(name, version);
    request.onsuccess = () => resolve(request.result);
    request.onerror = () => reject(request.error);
  });
}

async function openTasksBucket() {
  const bucket = await navigator.storageBuckets.open('tasks', {
    persisted: true,
  });
  const db = await openIndexedDB(bucket.indexedDB, 'tasks-db', 1);
  return db;
}

Per Chrome’s guide, open() accepts a boolean persisted option. The WICG explainer says the user agent may decline a persisted: true request, and that a persistent bucket is not evicted under storage pressure without user notice.

The durability option’s history

Chrome’s guide (last updated 2022-11-04) documents open() accepting a durability option — 'strict' or 'relaxed' — as a hint that trades write performance against the risk of data loss after power failure. The archived proposal describes writes as complete after persistence to the storage medium for strict, or after flushing to operating-system buffers for relaxed. The current WICG explainer for this API states that this policy “has been cautiously removed from the first version of the proposed API, although it may be added back in a later version,” citing limited compelling use cases and the fact that the same durability behavior remains available directly through IndexedDB’s own transaction options. Check both documents against your target browser’s current behavior before relying on a durability option — neither source alone establishes what today’s shipping implementation accepts.

Where it is supported

Per MDN’s browser-compat-data, StorageBucketManager (the interface behind navigator.storageBuckets) shipped in Chrome 122. Firefox and Safari do not implement it; treat storage buckets as a progressive enhancement over the origin’s default storage.

See the full per-browser support table for this feature.

Feature detection and fallback

async function openBucket(name) {
  if (!('storageBuckets' in navigator)) {
    // Unsupported: fall back to the origin's default IndexedDB/Cache storage.
    return null;
  }
  return navigator.storageBuckets.open(name);
}

Practical checklist

• Feature-detect with 'storageBuckets' in navigator before calling open() — Firefox and Safari do not implement this API.
• Don’t assume a durability option is accepted by open() without checking your target browser’s current, dated documentation — the WICG explainer describes it as removed from the proposed API, not as a shipped guarantee.
• Use separate buckets to give different app data separate eviction policies, rather than requesting persisted: true for everything.

Where to go next

• manifest: storage-buckets browser support
• Storage & offline — related storage capability guidance.