> ## Documentation Index
> Fetch the complete documentation index at: https://charli3-js-bc690dc5.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Quickstart

> npm install to a live ADA/USD price in a Next.js app, in under two minutes.

The shortest path from an empty Next.js app to a live on-chain ADA/USD price in your browser.

<Steps>
  <Step title="Create a Next.js app">
    ```bash theme={null}
    npx create-next-app@latest my-oracle-app
    cd my-oracle-app
    ```

    Pick any options. App Router is recommended.
  </Step>

  <Step title="Install the SDK">
    ```bash theme={null}
    npm install charli3-js
    ```

    No extra setup. Preprod and mainnet presets ship with each release, so just update the package when addresses change.
  </Step>

  <Step title="Read a price from a Server Component">
    Edit `app/page.tsx`:

    ```tsx app/page.tsx theme={null}
    import { Charli3 } from "charli3-js";

    export const revalidate = 30;

    export default async function Page() {
      const c3 = new Charli3({ network: "preprod" });
      const { price, outRef } = await c3.getOdvReference("ADA/USD");

      return (
        <main style={{ padding: 48, fontFamily: "ui-sans-serif" }}>
          <h1>ADA/USD on chain</h1>
          <p style={{ fontSize: 56, margin: 0 }}>
            ${price.value.toFixed(6)}
          </p>
          <p>
            {price.isExpired ? "stale, pull a fresh one" : "fresh"} /
            posted {price.createdAt.toISOString()}
          </p>
          <p style={{ opacity: 0.6, fontFamily: "monospace" }}>
            utxo {outRef.txHash.slice(0, 16)}...#{outRef.outputIndex}
          </p>
        </main>
      );
    }
    ```
  </Step>

  <Step title="Run it">
    ```bash theme={null}
    npm run dev
    ```

    Open [http://localhost:3000](http://localhost:3000). You should see the current ADA/USD price read directly from the Cardano preprod chain.
  </Step>
</Steps>

## What just happened

<AccordionGroup>
  <Accordion title="Where did the price come from?">
    `getOdvReference` asks a public indexer (Kupo) for the UTXO at Charli3's oracle address, reads the datum, and returns the price. No API key, no login, no subscription.
  </Accordion>

  <Accordion title="What if the price is stale?">
    `price.isExpired` tells you if the price is past its 5-minute window on preprod. If it is, call `c3.submitRound2(lucid, "ADA/USD")` to post a fresh one. See [Refreshing a price](/api-reference/charli3#submitround2).
  </Accordion>

  <Accordion title="Do I need a wallet?">
    Not for reading. You only need a wallet when you want to post a fresh price yourself. Reading is free and keyless.
  </Accordion>
</AccordionGroup>

## Next steps

<CardGroup cols={2}>
  <Card title="How the SDK works" icon="gears" href="/concepts/how-it-works">
    Round 1, Round 2, picking a price, and why the time window matters.
  </Card>

  <Card title="Sample app" icon="browser" href="/example-app/overview">
    A fuller example: Lace wallet, deposit and claim, AI invoice agent.
  </Card>

  <Card title="Refresh on-chain" icon="refresh" href="/api-reference/charli3#submitround2">
    Post a fresh price with Lucid and a funded wallet.
  </Card>

  <Card title="AI agents" icon="robot" href="/guides/ai-agents">
    One markdown file to teach any tool-calling LLM how to use Charli3.
  </Card>
</CardGroup>