---
title: Choosing a Model or Sign
description: Decide between the Model API and the Sign API, and pick a name.
type: doc
icon: git-branch
sidebar:
  label: Choosing a Model or Sign
  order: 2
  icon: git-branch
search:
  tags: [start]
---
A **sign** is one analysis target. A **model** is a named bundle of signs. These docs use **`pulse`** (General Wellness) as the primary model. The other bundles stay available.

## Model API or Sign API

| Interface | Endpoint | When `done`, `result` contains | Use when |
|---|---|---|---|
| Model API | [`POST /v2/models/{model_name}/analyze`](/reference/models) | `summary` + `signals[]` + `audio_quality` + `extended_metrics` | You want a named bundle and one aggregate routing decision (`summary.recommended_action`). |
| Sign API | [`POST /v2/signs/{sign_name}/analyze`](/reference/signs) | `signal` + `audio_quality` | Your workflow acts on exactly one sign. |

Prefer a named bundle when one matches your population. Use the Sign API when you need exactly one sign.

## How to choose a model

Start with **`pulse`** for general wellness or employee wellness. Specialized contexts (clinical behavioral health, substance use, cognition, sports, cardiometabolic, respiratory) have their own names.

If you serve more than one population, send a separate request with the most specific model for each group.

Eight bundles: `pulse`, `haven`, `clarity`, `aria`, `apex`, `harbor`, `tide`, `breath`. Domain, signs, and scenarios: [Model Catalog](/catalogs/models). Standalone vs model-internal signs: [Sign Catalog](/catalogs/signs). Live composition: `GET /v2/models` on the [Model API](/reference/models).

## Evidence tiers

Each sign is **Established**, **Emerging**, or **Investigational** (published research depth, not a product tier). Bundles mix tiers — put clinical oversight in place when you route on Emerging or Investigational signs. Definitions: [Sign Catalog — evidence tiers](/catalogs/signs#evidence-tiers). As-is statement: [Introduction](/guides#as-is).

## After you choose

- [Audio Requirements](/guides/audio-requirements) — formats, size, quality codes.
- [Quickstart](/guides/quickstart) — submit your first recording.
- [Interpreting Results](/guides/interpreting-results) — read `level` and `recommended_action`.
- [Billing and Cost](/guides/billing#token-rates) — the Model API and Sign API bill at different rates.

If no existing model fits your deployment context, contact [support@amplifierhealth.com](mailto:support@amplifierhealth.com) to discuss your requirements.