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

# Authentication

> How servers and apps authenticate to the NEUS API.

Pick the path that matches your caller. Most products use Hosted Verify for people and a profile access key for servers.

Credits apply to checks and saved results, not to hosted session sign-in. See [Trust stack](../platform/trust-stack) and [Pricing](../platform/pricing).

| Need | Mechanism | Wallet code in your app |
| - | - | - |
| Sign-in for your app | Hosted Verify + `intent=login` + `returnUrl` | No |
| Access or checkout (default) | `VerifyGate` / Hosted Verify + `gateId` | No |
| MCP client sign-in | OAuth 2.0 + PKCE | No |
| Server automation as your profile | Bearer `npk_*` access key | No |
| Server creates proofs for an approved user | App link + `verifyFromApp` | No |
| Sign inside your page | SDK `verify` + `wallet` | Yes. Rare |

Server integration: [Integrations](../cookbook/integrations).

## Hosted Verify (default)

`https://neus.network/verify` for [Hosted Verify](../cookbook/auth-hosted-verify).

Send users to your checkout with `gateId`; the enforcement policy bills your Hub credits.

## MCP OAuth

MCP clients authenticate via **OAuth 2.0 Authorization Code with PKCE**. Register `https://mcp.neus.network/mcp` and click **Connect** in the host. Official CLI: `npx -y -p @neus/sdk neus`.

Request only the scopes you need:

| Scope | What it unlocks |
| - | - |
| `neus:core` | Public protocol tools |
| `neus:profile` | Signed-in profile context |
| `neus:secrets` | Portable encrypted secrets |
| `offline_access` | Refresh token |

Profile access keys (`npk_*`) are a full-profile server credential.

See [Connect Proofable](../mcp/setup) and [MCP OAuth](../mcp/oauth).

## Profile access keys

[Access keys](https://neus.network/profile?tab=account) for servers, CI, and MCP automation. Never in browser bundles.

## Backend proofs

For backend-created proofs after a user approves your product once, see [Integrations](../cookbook/integrations). Separate from creating a **listing** under profile → **Listings**, which bills hosted verification to your account.

## Signing inside your app

[Signing format](../verification/signing-format) and `signMessage` from `@neus/sdk`

## Raw HTTP

`POST /api/v1/verification/standardize` → sign `signerString` → `POST /api/v1/verification`. [Signing format](../verification/signing-format).

[MCP Auth](../mcp/auth) and [SDK Authentication](../sdks/authentication)


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