List of free authentication stuff for developer๐๐ฝ
If you're looking for all programming tools around authentication (not just free). Check this page List of authentication Programming Tools

Back4appโข
Our simple, straightforward plans offer stability and predictability at the end of the month. No more surprise bills.
Tag: database, hosting, graphql, authentication, hosting-backend
Ideal for developing, learning and prototyping. Explore our features and start building with free monthly capacity of 25k requests, 250MB data storage, 1GB transfer, 1GB file storage. Supported by community.
MojoAuth
Quickly integrate passwordless authentication for web and mobile applications to give users a smooth, secure login experience.
Tag: authentication, passwordless-authentication
Unlimited Monthly Active Users Unlimited Total Users Unlimited Monthly Logins 2 RPS Authentication Request Email Support (Basic: 48 hours response time) Live Chat Support

PocketBase
Open Source backend in 1 file with realtime database, authentication, file storage and admin dashboard
Tag: database, hosting, hosting-dynamic, hosting-static, storage, authentication, real-time
Open Source, self hosted

AWS Amplify
Accelerate your full-stack web and mobile app development with AWS Amplify. Easy to start, easy to scale. No cloud expertise needed. Powered by AWS.
Tag: aws, baas, database, hosting, hosting-dynamic, hosting-static, storage, authentication
1 Year free Tier
Build & Deploy - 1000 build minutes per month
HOSTING: 5 GB stored per month 15 GB served per month

Appwrite
Appwrite provides web and mobile developers with a set of easy-to-use and integrate REST APIs to manage their core backend needs.
Tag: API, database, storage, authentication, serverless
Open Source

Nhost
Nhost is an open source Firebase alternative with GraphQL, built with the following things in mind: Open Source, GraphQL, SQL, Great Developer Experience
Tag: hosting, storage, database, authentication, serverless-backend, graphql
Postgres DB with 500 MB of storage GraphQL with Hasura Authentication upto 10,000 Storage up to 1GB Network Transfer upto 5GB ! Sleeps after 7 days of inactivity

Supabase
The Open Source Firebase Alternative Create a backend in less than 2 minutes. Start your project with a Postgres Database, Authentication, instant APIs, realtime subscriptions and Storage.
Tag: database, storage, authentication, real-time
Get free database, authentication and storage Unlimited API request Database space (Up to 500MB) Users 10.000 users Social Auth provider Storage Up to 1GB Transfer Limit Up to 2GB Team members: unlimited

StaticBackend
Free and open-source self-hosted backend API enabling web and mobile developers to use common building blocks for applications. Easy to deploy Firebase alternative includes authentication, database, storage, real-time database and WebSocket, server-side functions, task scheduler, sending emails, and more.
Tag: API, database, storage, authentication, real-tie, serverless
Self-host a feature-rich backend API.

Web3Auth
Web3Auth is a simple, non-custodial auth infrastructure that enables Web3 wallets and applications to provide seamless user logins to both mainstream and native Web3 users.
Tag: authentication, web3
Unlimited project creation for plug and play products Full dashboard access Access to SSO, passwordless and biometric logins Connect to any supported blockchain Ulimited project creation for plug and play products Up to 1,000 MAU
SuperTokens, Open Source Authentication
Add simple email and password sign up functionality to your site or app in 15 minutes
Tag: authentication
Self hosted: Free forever, unlimited users SaaS (hosted by us): Free up to 5K monthly active users

Firebase
Firebase helps you build and run successful apps Backed by Google and loved by app development teams - from startups to global enterprises
Tag: database, hosting, hosting-dynamic, hosting-static, storage, authentication, real-time
Authentication 10k/month Cloud Firestore (stored data: 1 GiB total) Realtime Database (stored data: 1 GB) Hosting storage 10 GB Cloud storage 5 GB

Magic
Fast, secure passwordless login for your app or website. One SDK for email magic links, social login, WebAuthn, and more. Free to get started, ready in minutes.
Tag: authentication, passwordless-authentication
1,000 free monthly active users 100 free text messages per month Access to all login methods Access to all 20 blockchains Custom logo and theme Magic Login Form and User Settings