> ## Documentation Index
> Fetch the complete documentation index at: https://docs.unseen.finance/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Why Unseen Pay exists — Solana-native payments, confidentiality, and how this documentation progresses from concepts to working code.

## Why Solana, and why payments need a gateway

Solana gives you fast settlement, cheap fees, and a single global ledger—ideal for moving value in real time. **[Solana Pay](https://solanapay.com)** and the wider ecosystem made it straightforward to request and settle payments on-chain: wallets, QR flows, and merchant standards are mature, and developers can build checkout experiences that feel familiar to web users.

Those patterns are powerful for **transparent** payments—where revealing the destination, amount, and flow on-chain is acceptable.

## The gap Unseen Pay fills

Many products need **stronger confidentiality**: shielding counterparty or amount details from public graph analysis, meeting compliance without advertising every transfer, or simply matching user expectations from traditional card privacy.

**Unseen Pay** is a **confidential payment gateway** on Solana. It sits between your application and the chain: you create **payment sessions**, your customers pay through wallets and hosted checkout flows, and Unseen helps you **verify settlement** and automate fulfillment—without turning your integration into raw, hand-rolled chain plumbing.

## What you gain

* **Privacy-oriented checkout** — Designed for flows where public, fully transparent payment rails are not enough.
* **Familiar merchant model** — Sessions, references, webhooks, verify calls—similar rhythm to other payment APIs.
* **Two official SDKs** — **`@unseen_fi/sdk`** for secure server work (create/list/verify, webhook HMAC), and **`@unseen_fi/ui`** for React checkout (modal, wallet picker, client verification).
* **Operational hooks** — **`payment.confirmed`**-style webhooks and **`payments.verify`** so you can fulfill orders idempotently next to your own database.

## Who this is for

Teams building **wallets, marketplaces, SaaS billing, or gated content** on Solana who want a **hosted gateway + SDKs** rather than re-implementing confidential settlement end to end.

***

## How this documentation is organized

Read in order—the sidebar matches this sequence so each page assumes the previous one.

| Step | Page                                             | You will                                                  |
| ---- | ------------------------------------------------ | --------------------------------------------------------- |
| 1    | **Introduction** (this page)                     | Understand motivation, benefits, and vocabulary.          |
| 2    | [Quickstart](/quickstart)                        | Run the minimal server + React flow end to end.           |
| 3    | [Architecture](/concepts/architecture)           | See how browser, backend, Unseen API, and Solana connect. |
| 4    | [Environments](/concepts/environments)           | Align `network`, `baseUrl`, and hosts for SDK vs UI.      |
| 5    | [Payment lifecycle](/concepts/payment-lifecycle) | Learn statuses, verify outcomes, and fulfillment habits.  |
| 6    | [Server SDK](/sdk/server/installation)           | Install and call the API from Node.                       |
| 7    | [Webhooks](/webhooks/overview)                   | Operate signed webhooks in production.                    |
| 8    | [React SDK](/sdk/react/installation)             | Embed checkout in your front end.                         |
| 9    | [Guides](/guides/nextjs-checkout)                | Apply patterns (Next.js route, Express webhook).          |
| 10   | [Troubleshooting](/troubleshooting)              | Fix common errors quickly.                                |
| 11   | [Changelog](/changelog)                          | Track doc and package releases.                           |

Underlying pages (for example [Client & payments](/sdk/server/client-payments) or [Hooks & wallets](/sdk/react/hooks-wallets)) appear **inside** each sidebar group in the same order they should be read.

***

## At a glance — request flow

Once you have gone through [Architecture](/concepts/architecture), this diagram will match the words you use for each hop.

```mermaid theme={null}
sequenceDiagram
  participant Browser
  participant YourAPI as Your backend
  participant Unseen as Unseen gateway
  participant Chain as Solana

  Browser->>YourAPI: Start checkout
  YourAPI->>Unseen: Create session (secret key)
  Unseen-->>YourAPI: Checkout URL + session fields
  YourAPI-->>Browser: Hand off to UI / link
  Browser->>Unseen: Customer pays (wallet / checkout)
  Browser->>Unseen: Verify (token or merchant auth)
  Unseen->>Chain: Confirm settlement
  Unseen-->>Browser: Status
  Unseen->>YourAPI: Signed webhook (optional)
```

**Next:** [Quickstart](/quickstart)