---
title: "GET a collection of V2 and V3 API List IDs"
method: GET
path: "/contact_lists/list_id_xrefs"
tags: ["Contact Lists"]
---

# GET a collection of V2 and V3 API List IDs

`GET /contact_lists/list_id_xrefs`

<div class="Msg Msg--warning"><p class="note-text">Use this endpoint to migrate your locally stored V2 contact list data to the new V3 format. Developers are expected to use this endpoint sparingly. This endpoint is NOT intended for regular or repeated use. Constant Contact will eventually deprecate and remove this endpoint.</p></div>

This GET call retrieves a collection of cross-referenced list sequence IDs (`id` used in the V2 API) and UUIDs (`list_id` used in the V3 API). This endpoint is intended for developers who have an existing V2 API integration, and are migrating their users to a new V3 API integration. The V2 and V3 APIs use different resource ID formats. Use the `sequence_ids` query parameter to specify a set of comma delimited V2 list ids to cross-reference. See [Migrating Apps and Data to V3](/api_guide/migration_overview.html) to learn more."

## Query parameters

- `sequence_ids` string, csv, required

## Response `200`

Request successful

- ListXrefs
  - `xrefs` ListXref[] — An array of cross-referenced V3 API <code>list_id</code> and V2 API <code>sequence_id</code> properties. Response is sorted ascending by <code>sequence_id</code>.
    - `sequence_id` string — The V2 API list unique identifier
    - `list_id` string, uuid — The V3 API list unique identifier

## Other responses

- `400` — Bad request. Either the JSON was malformed or there was a data validation error.
- `401` — The Access Token used is invalid.
- `403` — Forbidden request. You lack the necessary scopes, you lack the necessary user privileges, or the application is deactivated.
- `404` — The requested resource was not found.
- `500` — There was a problem with our internal service.
- `503` — Our internal service is temporarily unavailable.

---

[API](https://skmtc.net/cc/apis/appconnect-v3.md) · [All operations](https://skmtc.net/cc/apis/appconnect-v3/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/cc/appconnect-v3/versions/4b4a534c818d/schema)