The best alternatives to authzed are TypingDNA, Servicebot, and Base API. If these 3 options don't work for you, we've listed a few more alternatives below.
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Universal-2 by AssemblyAI— Speech-to-Text API for conversational data
At TypingDNA, we recognize people by the way they type. Our mission is to improve security without compromising user convenience with our suite of Continuous Authentication and 2FA products. Learn more at typingdna.com
Provide your customers with beautiful Pricing Pages, Signup Forms, and Subscription Management Portals. Servicebot is the Stripe Billing UI toolkit to scale your subscription business.
Base offers your next project an API that handles user flow (sign up, sign in, forgot password), email sending, file upload, image upload and processing including crop and resize, all with only one API key and a nice clean UI.
DAuth - Login using Ethereum is the easiest way to allow users to login using their account on Ethereum. As simple as adding Facebook and Google logins. A completely decentralized alternative to OAuth Users can now login from any device without needing to install MetaMask/Mist and without the need to make any paid transactions!
Authenticator is a two-factor authentication app that securely stores, generates, and manages your 2FA authentication tokens. All your accounts a synchronized between all your Apple devices and securely backed up in the encrypted form on your iCloud account.