---
title: "Add Companies To List"
method: POST
path: "/v1/company_lists/{list_id}/add_companies"
tags: ["Company Lists"]
---

# Add Companies To List

`POST /v1/company_lists/{list_id}/add_companies`

## Request

- Base URL: `https://api.theirstack.com`
- URL: `https://api.theirstack.com/v1/company_lists/{list_id}/add_companies`
- Auth: HTTP bearer
- TypeScript: <https://skmtc.dev/theirstack/apis/theirstack-api-reference/docs/v1/company_lists/:list_id/add_companies/post.ts> (a function with typed inputs; its response is checked against the schema)

Add companies to one of the team's company lists by their company IDs, the `id` of each company in a company search result. Returns the list with its new company count. If a company is not found, nothing is added and the error names the IDs that were not found.

## Path parameters

- `list_id` integer, required

## Request body

- AddCompaniesToListRequestV1
  - `company_ids` string[], required: Company IDs to add, the `id` of each company in a company search result

## Response `200`

Successful Response

- CompanyListResponseV1: Named for v1 so what this version promises can outlive a change to the schema.
  - `name` string, required: Name of the company list
  - `id` integer, required
  - `created_at` string, date-time, required
  - `deletable` boolean, nullable: Whether the list can be deleted
  - `companies_count` integer: Number of companies in the list
  - `user_id` integer, nullable: User ID of the list owner
  - `type` 'REVEALED_COMPANIES' | 'WEBHOOK_TRIGGERED' | 'MANUAL_CREATION' | 'EXPORT_SNAPSHOT' | 'INTERNAL_WEBHOOK_TRIGGERED' | 'CUSTOMER_CRM_SYNC'
  - `webhook_id` integer, nullable: Webhook ID of the list
  - `customer_crm_connection_id` integer, nullable: CRM connection that keeps this list in sync (CUSTOMER_CRM_SYNC lists)

## Other responses

- `400`: Bad Request
- `402`: Payment Required
- `422`: Unprocessable Content
- `500`: Internal Server Error

## Changes

- **2026-11-04** `52d42d210949`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/theirstack/apis/theirstack-api-reference/changes/v1/company_lists/:list_id/add_companies/post.md)

---

[API](https://skmtc.dev/theirstack/apis/theirstack-api-reference.md) - [All operations](https://skmtc.dev/theirstack/apis/theirstack-api-reference/llms.txt) - [OpenAPI document](https://skmtc.dev/theirstack/apis/theirstack-api-reference/revisions/062c9906e3d5?raw)