> For the complete documentation index, see [llms.txt](https://bountyv.gitbook.io/vdocs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bountyv.gitbook.io/vdocs/soul-api/soul-overview.md).

# Overview

Persist a face once, then generate identity-locked imagery from it forever. Souls are reusable across pipelines — create a Soul a single time and call it from as many text-to-image requests as you need, without re-uploading reference photos.

> Access to this API group is gated by your account's `soul` entitlement. If a call returns `403 product_disabled`, contact your account manager.

## What is a Soul?

A Soul is a stored identity record — a small set of reference faces plus the metadata needed to lock subsequent generations to that person. Once created, a Soul has a stable `id` you reuse in generation calls instead of re-uploading a face photo every time.

## Endpoints

| Endpoint                                                       | Method                                  | Description                                                    |
| -------------------------------------------------------------- | --------------------------------------- | -------------------------------------------------------------- |
| [Create a Soul](/vdocs/soul-api/identities-create.md)          | `POST /api/v1/identities/create`        | Upload a reference face and persist it as a reusable identity. |
| [Generate from a Soul](/vdocs/soul-api/identities-generate.md) | `POST /api/v1/identities/{id}/generate` | Identity-locked text-to-image using a previously created Soul. |

## Quick start

```bash
# 1. Create a Soul
curl -X POST https://substance-api.com/api/v1/identities/create \
  -H "Authorization: Bearer sk_live_..." \
  -F "face=@face.jpg" \
  -F "name=Anna"

# 2. Generate from it
curl -X POST https://substance-api.com/api/v1/identities/id_abc123/generate \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{"prompt": "portrait under neon rain, 35mm"}'
```

## Authentication

All Soul endpoints require the standard header:

```
Authorization: Bearer sk_live_...
```

See [Authentication](/vdocs/authentication.md) for details.

## Consent requirement

Every face you upload to create a Soul must be backed by documented consent from the person depicted.

## Pricing

Creating a Soul is billed once, per Soul. Generating from a Soul is billed per call. See [Credits & pricing](/vdocs/account/credits.md) for current rates.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://bountyv.gitbook.io/vdocs/soul-api/soul-overview.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.