---
title: "Create a model builder"
method: POST
path: "/model_builders"
tags: ["Model builders"]
---

# Create a model builder

`POST /model_builders`

## Request

- Base URL: `https://api.ionworks.com`
- URL: `https://api.ionworks.com/model_builders`
- Auth: none declared

Create a builder whose config is a pipeline of entry and calculation elements.

## Request body

- CreateModelBuilder: Body for creating a model builder.
  - `model_id` string, required: Model the builder produces parameters for.
  - `project_id` string, required: Project the builder belongs to; names are unique per project.
  - `name` string, required
  - `description` string, nullable
  - `config` object, required: An ionworks_schema Pipeline config (Pipeline(...).to_config()) of entry and calculation elements. An entry that reads the cell spec is a DirectEntry cell spec entry without its cell_spec_id: {'element_type': 'entry', 'mapping': {parameter: 'dotted.path'}}.

## Response `201`

Successful Response

- ModelBuilder: A model_builders row.
  - `id` string, required
  - `organization_id` string, required
  - `project_id` string, required
  - `model_id` string, required
  - `name` string, required
  - `description` string, nullable
  - `config` object, required: Pipeline config of entry and calculation elements.
  - `created_by` string, nullable
  - `created_at` string, date-time, nullable
  - `updated_at` string, date-time, nullable

## Other responses

- `422`: Validation Error

## Changes

- **2026-10-22** `39d84bb8875e`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/ionworks/apis/ionworks-api/changes/model_builders/post.md)

---

[API](https://skmtc.dev/ionworks/apis/ionworks-api.md) - [All operations](https://skmtc.dev/ionworks/apis/ionworks-api/llms.txt) - [OpenAPI document](https://skmtc.dev/ionworks/apis/ionworks-api/revisions/abebbbc5f60a?raw)