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

# Sign in with Neuro

> Let an existing Neuro account and Legal Identity enter an application

Use this guide when the user already has a Neuro account or Legal Identity. Do not create a duplicate identity merely to establish an application session.

<Warning>
  Login and cross-Neuron behavior differ by deployment. Use only the login flow and redirect behavior confirmed by the target Neuron's operator.
</Warning>

## Start here

* Use the [Agent API quickstart](/neuron-api/quickstart) to test backend login with an existing account.
* Compare the documented options in [Login flows](/neuron-api/guides/login-flows).
* Use [Browser-based signup](/neuron-api/guides/browser-based-signup) when a user needs an interactive Neuron form.
* Check request fields in the [authentication and sessions reference](/neuron-api/api-reference/authentication-and-sessions/overview).

## Workflow choices

| Need                                                   | Relevant flow                                                                              |
| ------------------------------------------------------ | ------------------------------------------------------------------------------------------ |
| Sign in to the current Neuron with account credentials | [Login flows](/neuron-api/guides/login-flows)                                              |
| Use an interactive browser onboarding session          | [Browser-based signup](/neuron-api/guides/browser-based-signup)                            |
| Initiate Quick Login                                   | [Quick Login reference](/neuron-api/api-reference/authentication-and-sessions/quick-login) |
| Prepare or complete login across Neurons               | Prepare Remote Quick Login and Remote Quick Login in the API reference                     |

## Application responsibilities

* Bind the Neuro session to the correct application user.
* Let the user select the Legal Identity used for the application workflow.
* Keep JWTs and session cookies out of URLs and logs.
* Handle rejection, expiry, cancellation, and remote-Neuron failure.
* End both the application session and Neuro session as required by the product's logout policy.

Test cancellation, expiry, logout, and remote-Neuron failure on the deployment before enabling the flow for users.