---
title: "Public username check. Returns availability and up to 5 free suggestions. 30 requests per minute per IP. Responses include RateLimit-Limit, RateLimit-Remaining, and RateLimit-Reset (seconds until the window ends). HTTP 429 rate_limited includes Retry-After, retry_after_seconds, and resets_at, and RateLimit-Reset matches Retry-After. A lookup that cannot be completed returns HTTP 503 username_check_unavailable. If the limit cannot be checked, the response is HTTP 503 rate_limit_unavailable. Both 503 responses include Retry-After, retry_after_seconds, and resets_at."
method: GET
path: "/api/v1/usernames/check"
tags: ["Auth"]
---

# Public username check. Returns availability and up to 5 free suggestions. 30 requests per minute per IP. Responses include RateLimit-Limit, RateLimit-Remaining, and RateLimit-Reset (seconds until the window ends). HTTP 429 rate_limited includes Retry-After, retry_after_seconds, and resets_at, and RateLimit-Reset matches Retry-After. A lookup that cannot be completed returns HTTP 503 username_check_unavailable. If the limit cannot be checked, the response is HTTP 503 rate_limit_unavailable. Both 503 responses include Retry-After, retry_after_seconds, and resets_at.

`GET /api/v1/usernames/check`

## Request

- Base URL: `https://cooperemail.com`
- URL: `https://cooperemail.com/api/v1/usernames/check`
- Auth: none required

## Query parameters

- `name` string

## Response `200`

Availability. No account id and no holder.

- object
  - `name` string, required
  - `normalized` string, required
  - `available` boolean, required
  - `reason` 'invalid_username' | 'reserved_username' | 'taken'
  - `suggestions` string[], required

## Other responses

- `429`: rate_limited. Retry-After, retry_after_seconds, and resets_at. RateLimit-Limit, RateLimit-Remaining 0, and RateLimit-Reset matching Retry-After.
- `503`: username_check_unavailable when the lookup cannot be completed, or rate_limit_unavailable when the limit cannot be checked. Retry-After, retry_after_seconds, and resets_at.

---

[API](https://skmtc.dev/cooperemail/apis/cooper-email-api.md) · [All operations](https://skmtc.dev/cooperemail/apis/cooper-email-api/llms.txt) · [OpenAPI document](https://skmtc.dev/cooperemail/apis/cooper-email-api/revisions/6d800a7b3e33?raw)