Fern vs username.dev: which is better? (2026)

username.dev

Prevent abusive usernames, protect brands, and support premium handles in one API.

username.dev is an API for developers and product teams who need to validate usernames before they enter a database. It focuses on three problems that come up whenever a signup form asks someone to pick a handle: abusive or offensive names, brand impersonation, and premium or reserved handles. What username.dev does Checks submitted usernames for abusive or offensive content before account creation Flags names that could be used to impersonate existing brands Identifies premium or reserved handles so they can be treated differently in a signup flow Exposes this checking logic through a single API that can be called during registration Who it's for username.dev is built for developers and teams building products with user accounts, such as social apps, marketplaces, communities, and any platform where users choose their own public-facing name. Teams use it to keep offensive or brand-infringing usernames out of their systems and to manage which handles count as premium. For a maker setting up a signup flow, username.dev fits in as a validation step called at account creation, alongside existing checks like email or password rules, so username quality and brand protection are handled through one API call rather than custom moderation logic built in-house. }