User authentication services with a free tier. 3 providers, each with the free-tier text from its official pricing page and the date we checked it.
Free tier: Hobby (Free, no card): 50,000 MRU per app, unlimited applications, up to 3 dashboard seats, prebuilt sign-in/up UIs, custom domain, fixed 7-day sessions.
Free tier: Free $0/month, no card: up to 25,000 monthly active users, 1 custom domain, passwordless, unlimited social connections.
Free tier: User management free up to 1 million users (then $2,500/mo per additional 1M); Radar free tier 1K.
Each free tier was read from the provider’s official pricing or limits page on 17 Oct 2026 and is linked as the source. Anything the page does not state is written as unknown. Free tiers change often, so confirm before you build on one.