How does IndexedDB compare to WebSQL and localStorage?

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Shalini Passi · Answer

IndexedDB is the modern, recommended way to store structured data in the browser. Here's a clear comparison between IndexedDB, WebSQL, and localStorage, including their features, support, and limitations: Feature IndexedDB WebSQL (Deprecated) localStorage Data Size Limit Hundreds of MBs+ ~5–50 MB (varies) ~5–10 MB Structure Support Structured objects Relational only (SQL) String-only Async API Yes (event or promise) Async but SQL-based No, it's synchronous Binary Data Support Yes (Blobs, Files) Yes (via base64 hacks) No Query Type Indexed (No SQL) SQL Queries (Relational) Key-value only Performance Excellent for large data Moderate Poor for large data Multi-store support Yes (Object Stores) Tables No Transactions Yes Yes No Browser Support All modern browsers Deprecated in all All Offline support Yes Yes Yes 1. IndexedDB Stores structured data (objects, files, blobs).Uses object stores (like tables) and indexes for fast lookups.Asynchronous API (event-based or promise-based via wrappers like idb).Built for complex, large-scale offline storage.Binary-safe and scalable.Recommended for modern apps that need structured, reliable offline storage. 2. WebSQL (Deprecated) Uses SQL for querying (like SQLite).Good for relational data, but: Deprecated by W3C: no new features, limited future supportNot available in some environments (e.g., Firefox, Safari 16+) Only useful for legacy apps.Avoid using WebSQL in new projects. 3. localStorage Simple key-value storage (strings only).Synchronous API — blocks the main thread.Good for small settings or flags (theme, token, etc.). Not suitable for storing large data or binary files. Use Case Summary Use Case Recommended Storage User settings, theme, token localStorage Large datasets (e.g., messages, images) IndexedDB Offline-first apps (PWA, sync cache) IndexedDB Legacy apps using SQL WebSQL (avoid now) Saving files/blobs IndexedDB Conclusion Use IndexedDB for anything beyond simple string values. It is: ModernAsynchronousStructuredEfficientFully supported

Feature	IndexedDB	WebSQL (Deprecated)	localStorage
Data Size Limit	Hundreds of MBs+	~5–50 MB (varies)	~5–10 MB
Structure Support	Structured objects	Relational only (SQL)	String-only
Async API	Yes (event or promise)	Async but SQL-based	No, it's synchronous
Binary Data Support	Yes (Blobs, Files)	Yes (via base64 hacks)	No
Query Type	Indexed (No SQL)	SQL Queries (Relational)	Key-value only
Performance	Excellent for large data	Moderate	Poor for large data
Multi-store support	Yes (Object Stores)	Tables	No
Transactions	Yes	Yes	No
Browser Support	All modern browsers	Deprecated in all	All
Offline support	Yes	Yes	Yes

Use Case	Recommended Storage
User settings, theme, token	`localStorage`
Large datasets (e.g., messages, images)	`IndexedDB`
Offline-first apps (PWA, sync cache)	`IndexedDB`
Legacy apps using SQL	`WebSQL` (avoid now)
Saving files/blobs	`IndexedDB`

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How does IndexedDB compare to WebSQL and localStorage?

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1 Answers

1. IndexedDB

2. WebSQL (Deprecated)

3. localStorage

Use Case Summary

Conclusion