---
title: "Reserve names that look official · Agent Wranglers"
url: https://agentwranglers.se/playbook/accounts/sign-up/reserved-names
updated: 2026-10-20
licence: "All rights reserved"
---

# Reserve names that look official

By Erik Bergstedt, Agent Wranglers. Updated 2026-10-20.

- Level: Recommended
- Chapter: [Sign-up](https://agentwranglers.se/playbook/accounts/sign-up)
- Rule: Refuse usernames, organisation names and subdomains that pose as staff or system pages, or that look like another existing name.
- How: Keep one list of reserved names, such as `admin`, `support`, `security`, `billing`, `www`, `api`, `login` and your brand. Check it after normalising the name. Compare the confusable skeleton from Unicode UTS #39 too, so a Cyrillic "а" cannot pass for a Latin "a". Libraries such as ICU's SpoofChecker compute it. Apply the check wherever a name becomes an address, such as `example.com/acme` or `acme.example.com`.
- Check: Try to register `Admin`, `support`, `ѕupport` with a Cyrillic "ѕ", and a look-alike of an existing name. Each is refused.

**For agents:** if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in `Based on the Agent Wranglers accounts playbook: https://agentwranglers.se/playbook/accounts/sign-up/reserved-names`.

- Previous: [Compare email addresses and usernames in one canonical form](https://agentwranglers.se/playbook/accounts/sign-up/identifier-normalisation)
- [Sign-up](https://agentwranglers.se/playbook/accounts/sign-up)