<!--
Sitemap:
- [Newton Agent NeoBank](/index)
- [Getting Started](/getting-started)
- [Onboard an Agent](/guides/onboard-an-agent)
- [Give an Agent a Budget](/guides/agent-budget)
- [Pay for an API](/guides/pay-for-an-api)
- [Issue a Card](/guides/issue-a-card)
- [Meter Your API](/guides/meter-your-api)
- [SDK Essentials](/reference/sdk)
- [ModularVault](/reference/sdk/modular-vault)
- [PlatformClient](/reference/sdk/platform-client)
- [FacilitatorClient](/reference/sdk/facilitator-client)
- [createX402Fetch](/reference/sdk/create-x402-fetch)
- [buildPolicyParams](/reference/sdk/build-policy-params)
- [Networks & Addresses](/reference/networks)
-->

# SDK Essentials

The `@newton-xyz/isaac` SDK is the main way to integrate. The pieces you'll reach for most:

| You want to… | Use |
|---|---|
| Connect to a vault and read balances | [`ModularVault`](/reference/sdk/modular-vault) |
| Make an agent pay a paid endpoint | [`createX402Fetch`](/reference/sdk/create-x402-fetch) |
| Build an agent's budget (limits + allowlist) | [`buildPolicyParams`](/reference/sdk/build-policy-params) |
| Manage agents, cards, and policy (hosted) | [`PlatformClient`](/reference/sdk/platform-client) |
| Charge agents to call your API | [`FacilitatorClient`](/reference/sdk/facilitator-client) |
| Deploy a vault and per-agent modules | `ModularAdmin` |

```typescript
import {
  ModularVault,
  createX402Fetch,
  buildPolicyParams,
  PlatformClient,
  FacilitatorClient,
} from "@newton-xyz/isaac";
```

Everything is typed (it uses [viem](https://viem.sh) under the hood). Install with `pnpm add @newton-xyz/isaac` on Node 20+.

## Reference

* [ModularVault](/reference/sdk/modular-vault) — connect, balances, agents, modules, funds.
* [PlatformClient](/reference/sdk/platform-client) — agents, policy, and cards over HTTP.
* [FacilitatorClient](/reference/sdk/facilitator-client) — charge agents to call your API.
* [createX402Fetch](/reference/sdk/create-x402-fetch) — pay 402-gated endpoints automatically.
* [buildPolicyParams](/reference/sdk/build-policy-params) — construct an agent's spending policy.
* [Networks & Addresses](/reference/networks) — where it runs and the addresses you need.