---
title: "Add contacts to a list"
method: POST
path: "/v1/lists/members"
tags: ["Lists"]
---

# Add contacts to a list

`POST /v1/lists/members`

## Request

- Base URL: `https://api.automatedclientacquisition.com`
- URL: `https://api.automatedclientacquisition.com/v1/lists/members`
- Auth: HTTP bearer

Adds existing contacts to a lead list. Batched server-side, so passing several
thousand IDs in one call is fine.

Pass either `contactIds`, or `sourceListId` together with `filters` to copy a
filtered subset of another list without moving IDs through your own code.

## Request body

- object
  - `listId` string, uuid, required: Target lead list.
  - `contactIds` string[]: Contacts to add.
  - `sourceListId` string, uuid: Copy members from this list instead of passing IDs. Requires `filters`.
  - `filters` object: Applied to `sourceListId` to resolve the subset server-side.

## Response `200`

Members added.

- object
  - `success` boolean
  - `added` integer

## Other responses

- `400`: Malformed or invalid body. Do not retry — it will fail identically.
- `401`: Missing, invalid or revoked token.
- `403`: The resource belongs to another organization.
- `404`: List not found.
- `500`: Something broke on our side. Safe to retry with backoff.

---

[API](https://skmtc.dev/automatedclientacquisition/apis/aca-api.md) · [All operations](https://skmtc.dev/automatedclientacquisition/apis/aca-api/llms.txt) · [OpenAPI document](https://skmtc.dev/automatedclientacquisition/apis/aca-api/revisions/8f3e3b141311?raw)