Storage Fingerprinting

Storage fingerprinting tests which storage APIs are available and reads storage quota estimates. Quota values differ between normal and incognito browsing.

Collected signals

Signal	What it checks
localStorage	Can write and read
sessionStorage	Can write and read
indexedDB	Is available
cookieEnabled	navigator.cookieEnabled
storageEstimate	navigator.storage.estimate() quota and usage
privateBrowsing	Quota below 120MB heuristic

Role in incognito detection

Storage quota is the primary signal for detecting private browsing:

• Chrome normal: ~10GB quota
• Chrome incognito: ~4GB quota
• Safari normal: ~80GB quota
• Safari private: ~1GB quota

Entropy and stability

Property	Value
Entropy	~4 bits
Stability	0.60
Typical duration	5-7ms

Excluded in incognito-resistant mode because values change in private browsing.

Usage

const fp = await neoprint.get({ collectors: ['storage'] })
const s = fp.components.storage.value

console.log(s.localStorage)     // true
console.log(s.storageEstimate)  // { quota: 10737422464, usage: 4224 }