# Curvy SDK

> [!TIP]
> This page aims to explain the core concepts behind Curvy SDK.
> If you're looking to build with Curvy SDK, visit the [Curvy for programmers](/for-programmers/installing-the-sdk.md) section.

The Curvy SDK facilitates:

- Logging into Curvy
- Key derivation
- Syncing the local Merkle tree from the [Indexer](./privacy-aggregator#off-chain-services)
- Note scanning
- Portal scanning and recovery
- Signing notes
- Generating ZK proofs on the user's device (the **Local ZK prover**)
- Planning intent execution
- Executing intents
- Retrying failed attempts
- Resolving Curvy IDs
- Gas sponsorship through the [Relayer](./privacy-aggregator#gasless-and-anonymous-relaying), paid from the shielded balance itself — no native gas tokens needed
- Anonymous, rate-limited relaying using blind-signed Privacy Pass tokens

all through a simple API that lets the user specify the **intent**, rather than an explicit set of actions.

To accomplish this, the SDK has background processes that sync and scan Notes, Portals, and other potential sources of users' balances to build a coherent picture
of their private portfolio.

This is what we refer to as **Balance Storage**.

The brains of the SDK is what we call the **Planner**.

The Planner can execute simple intents such as:

```typescript
import { estimateIntent, executeIntent, refreshBalances } from "@0xcurvy/curvy-sdk/actions";

const estimation = await estimateIntent({
  config,
  intent: {
    type: "external-transfer",
    recipient: "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
    amount: parseEther("1"),
    currency,
    network,
  },
});

await executeIntent({ config, prepared: estimation.prepared });

await refreshBalances({ config });
```

The above code snippet will generate a plan for transferring 1 ETH to an external address.
Because a user's balance could be fragmented across different contracts, stealth addresses, and notes, it is the **Planner's** task to create an execution plan that
pools the funds together **without sacrificing privacy**.

The smallest unit of execution within the SDK's Planner and Executor is called a **Command**.

We are currently working on examples of third-party Commands you can add to the Curvy SDK to allow for custom dApp and DeFi interactions.

> [!NOTE]
> The Curvy SDK is 100% open-source and is used as-is in the [Curvy App](https://app.curvy.box) (we ❤️ dogfooding).
> <br>
> We invite you to take a look at the [0xCurvy/sdk](https://github.com/0xCurvy/sdk/) GitHub repository and open issues for any improvements or bugs you can think of.