---
title: "Local Storage Method Group"
description: "TrUAPI Local Storage method group for per-Product, per-device key-value persistence, Host-managed namespaces, JSON helpers, and KvStore use."
categories: "Apps, Reference"
url: "https://developers.polkadot.com/reference/apps/protocol/truapi/local-storage/"
word_count: 319
token_estimate: 515
version_hash: "sha256:1fbe30d99748181e6ee1e503b3a7fbdd2d0b2b900d0a0f2a4d1de4a0a9216548"
last_updated: "2026-11-13T11:04:04+00:00"
---

# Local Storage

## Introduction

The Local Storage method group exposes the per-Product, per-device key-value store a Product uses to remember values between sessions, such as user preferences, drafts, and cached values. The Product SDK wraps this group as a `KvStore` in the [`@parity/product-sdk-local-storage`](https://www.npmjs.com/package/@parity/product-sdk-local-storage) package.

Two properties matter for how this group is shaped:

- **Per-Product namespacing**: The Host prepends every key with a prefix derived from the Product's `.dot` domain. A Product cannot accidentally read or write another Product's keys; the boundary is at the Host, not in the Product's code.
- **Host-dependent backend**: Inside Polkadot Desktop, reads and writes go to the Host's on-device storage. Inside Polkadot Web, the Host backs them with browser-managed storage. The SDK abstracts the difference; the Product's code is identical either way.

## Conceptual Contract

The group exposes the standard key-value surface plus a few helpers:

- **`get(key)`, `set(key, value)`, and `remove(key)`**: Read, write, and delete a string-valued key.
- **`getJSON(key)` and `setJSON(key, value)`**: Read and write JSON-serializable values, with the Host handling encoding.
- **Prefixed-namespace creation**: A Product can carve out further sub-namespaces inside its own per-Product space, useful when multiple Product features share the store and want to avoid collisions.

Reads return `null` for absent keys; deletes are idempotent (no error on missing keys).

:::caution[Provisional]
Quota policy (per-Product byte caps, eviction rules), the exact per-Host backend behavior (especially around Web's browser-managed storage), and any subscription-style key-change notifications are still being finalized. The basic key-value contract above is stable.
:::

## Where to Go Next

<div class="grid cards">

- **Persist Data Locally**

    ---

    The Product-side how-to: initializing the store, reading and writing values, prefix namespaces, error handling.

    [→ Get Started](/apps/build/persist-data-locally/)

</div>