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Save Systems for Browser Games: localStorage, IndexedDB, and Cloud Saves

October 9, 2026 · FarmHeart

Nothing kills player retention faster than lost progress. A save system is the difference between a toy and a game.

localStorage (Simple Saves)

Best for: games with small save data (scores, settings, level progress, inventory under 100 items).

• Storage limit: 5–10 MB per domain (varies by browser)
• API is dead simple: localStorage.setItem("save", JSON.stringify(data))
• Synchronous (blocks the main thread) — fine for small saves, bad for large ones
• Persists until the user clears browser data

IndexedDB (Large Saves)

Best for: games with complex state, large inventories, procedurally generated worlds, or replay data.

• Storage limit: effectively unlimited (browser asks user for permission above ~50 MB)
• Asynchronous — won’t freeze your game during save/load
• Supports structured data, binary blobs, and indexing for fast queries
• More complex API — use a wrapper library like Dexie.js or idb

Cloud Saves

For cross-device play. Options:

• Firebase Realtime DB: free tier handles thousands of players. Real-time sync between devices
• Supabase: open-source Firebase alternative. Postgres-backed, good free tier
• Custom API + Cloudflare KV: lightweight, fast, cheap. Good for simple key-value save data

Cloud saves require user accounts (email, Google sign-in, or anonymous accounts with upgrade path).

Auto-Save Best Practices

• Save after every significant action (level complete, item acquired, checkpoint reached)
• Debounce rapid saves: don’t save on every frame. Save at most once every 5–30 seconds during active play
• Show a save indicator: a brief icon so players know their progress is safe
• Keep multiple save slots: at minimum, keep the current save and one backup. Corrupted saves happen
• Version your save format: include a version number so you can migrate old saves when the game updates