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

# Introduction

> What the Endstate API does and how its core resources fit together.

Endstate gives physical products a secure digital identity — so brands can protect authenticity, deepen user engagement, and turn every product into a connected experience. This API is how you build them: create a digital record for each product, pair it with a secure NFC chip, and confirm a product is authentic the moment a user taps it. When a tap is verified, you receive a session token and the product's full digital record — ready to power ownership, loyalty, and any other product-aware action in your application.

The API is organized around three core resources — collections, units, and chips — and a lightweight verification call that ties them together. All resources are JSON, all requests are HTTPS, and the production base URL is `https://api2.endstate.io`.

## The mental model

* **Collection** — a group of related items (a product line, a drop, a release). Create a collection first; it defines the namespace that units within it share.
* **Unit** — the unique digital record for a single physical item. One unit maps to one physical product.
* **Chip** — a real, physical NFC chip (an [NTAG 424 DNA](https://www.nxp.com/products/NTAG424DNA)) attached to or embedded in the product. Pair a chip to a unit to link the hardware to its digital record. Each tap produces a fresh, one-time credential.
* **Verification** — pass that credential to the API to confirm the product is authentic. The API records the tap and returns a session token.
* **Session token** — short-lived proof that a specific chip was just tapped. Use it to authorize unit-scoped actions without exposing your API key.

<CardGroup cols={2}>
  <Card title="Quickstart" icon="rocket" href="/quickstart">
    Create a collection, add a unit, pair a chip, and run your first
    verification in minutes.
  </Card>

  <Card title="Authentication" icon="key" href="/authentication">
    Learn about API keys and session tokens — the two credentials the API uses.
  </Card>

  <Card title="Core concepts" icon="book-open" href="/concepts/overview">
    Understand collections, units, chips, and the verification model in depth.
  </Card>

  <Card title="API reference" icon="code" href="/api-reference/introduction">
    Full endpoint reference with request and response schemas.
  </Card>
</CardGroup>

## How it works

1. **Create a collection** — define a group for your items. The collection is provisioned asynchronously; poll until it is ready before adding units.
2. **Create a unit** — add a digital record for each physical item inside the collection.
3. **Pair a chip** — link the physical NFC chip on the item to the unit. This triggers issuance: the unit receives a serial number within the collection.
4. **User taps** — the tap URL delivers a `chip_id` and a one-time credential (`e` value) to your application.
5. **Verify** — send `chip_id` and `e` to `POST /v1/chips/{chip_id}`. The API validates the credential, records the tap, and returns the unit's metadata plus a session token.
6. **Use the session token** — pass it to `GET /v1/session-tokens/current` from your client to confirm scope without exposing the API key.

For testing without physical hardware, create a test chip (`is_test: true`) and use `POST /v1/chips/{chip_id}/tap` to simulate a tap.

## Next steps

* Follow the [Quickstart](/quickstart) to run a complete verification flow in a few minutes.
* Read [Core concepts](/concepts/overview) for a deeper look at how collections, units, and chips relate to each other.