---
title: "Lookup Usernames By Emails"
method: GET
path: "/api/v1/users/username-lookup"
tags: ["User APIs", "users"]
---

# Lookup Usernames By Emails

`GET /api/v1/users/username-lookup`

Return {email: username} for the given emails across all clients.

Username is a globally-unique public identifier (see username-availability),
so cross-client exposure is intentional. Missing users map to null.

## Query parameters

- `emails` string[]

## Response `200`

Successful Response

- UsernameLookupResponse
  - `items` UsernameLookupItem[], required
    - `email` string, required
    - `username` string, nullable

## Other responses

- `422` — Validation Error

---

[API](https://skmtc.net/carbonarc/apis/carbon-arc-client-admin-api.md) · [All operations](https://skmtc.net/carbonarc/apis/carbon-arc-client-admin-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/carbonarc/carbon-arc-client-admin-api/revisions/a8ca30023371/schema)