Google's Firebase is an entire app development platform that's packed with features.It comes with storage, cloud functions, monitoring and, of course, user authentication. The free tier comes with 50,000 MAUs. Beyond that pricing start at $0.0055/MAU and goes down to as low as $0.0025/MAU as you scale to millions of users. Firebase authentication supports email and password auth, phone auth, magic links, two-factor authentication and social identity providers - mainly Google, Google Play Games, Facebook, Apple, Microsoft, Twitter, GitHub and OAuth access tokens.

Auth0 is an identity and access management (IAM) platform designed to simplify authentication and authorization for applications. It provides a flexible solution that allows developers to implement secure login systems without having to build them from the ground up. Auth0 supports various authentication methods, including username-password credentials, social logins (like Google, Facebook, and GitHub), enterprise identity providers (such as Active Directory and SAML-based systems), and passwordless options. The platform is highly adaptable, offering over 30 software development kits (SDKs) that cater to a wide range of languages and frameworks—JavaScript, Python, .NET, iOS, Android, and more. This makes integration straightforward regardless of the tech stack. Beyond basic authentication, Auth0 offers advanced features like multi-factor authentication (MFA), single sign-on (SSO), and fine-grained authorization. These tools enable organizations to enforce complex access control policies, supporting both role-based (RBAC) and attribute-based (ABAC) models. Auth0 also addresses enterprise needs through features like user provisioning, directory synchronization, and support for B2B, B2C, and B2E use cases. It’s designed with scalability in mind, making it suitable for both startups and large enterprises. The platform’s extensibility allows developers to customize authentication flows, implement rules for conditional access, and integrate third-party services. Since its acquisition by Okta, Auth0 operates as a product unit under the Okta umbrella, complementing Okta’s broader suite of identity solutions while maintaining a developer-first focus. This combination brings together Okta’s enterprise-grade security with Auth0’s developer-centric approach, offering a comprehensive solution for modern identity challenges.

Clerk is a comprehensive user management and authentication platform designed to streamline how developers handle user accounts within web and mobile applications. It offers a suite of embeddable UI components—such as <SignIn/>, <SignUp/>, <UserButton/>, and <UserProfile/>—that integrate seamlessly into your application without redirecting users off-site. These components are fully customizable to match your brand, making the user experience cohesive and frictionless. Under the hood, Clerk provides a robust API and SDKs compatible with modern frameworks like Next.js, Remix, React, and Expo. It handles the entire authentication lifecycle, supporting multifactor authentication (MFA), session management, passwordless sign-in (via magic links or one-time passcodes), and traditional password-based methods with breach detection. The platform also integrates social sign-on (SSO) with over 20 providers, enabling quick user onboarding while adhering to security best practices. Clerk’s security posture includes SOC 2 Type 2 certification and CCPA compliance, with continuous third-party audits and penetration testing. Fraud prevention measures, like disposable email blocking and bot detection powered by machine learning, are built-in to reduce spam and abusive sign-ups. For B2B SaaS applications, Clerk provides advanced multi-tenancy features, enabling organization-based user management with custom roles, permissions, auto-join functionality based on email domains, and invitation systems—all accessible through both code and an admin dashboard. Developers benefit from rapid integration, significantly reducing the time spent on building authentication systems from scratch. Clerk acts as the single source of truth for user data and integrates seamlessly with popular backend services like Supabase, Firebase, and Convex. With free access for up to 10,000 monthly active users, it’s positioned as a scalable solution that grows with your application’s needs.

Supabase is the open-source alternative to Firebase. Like Firebase, it's a complete app development platform with user authentication, cloud functions, APIs, Postgres database, storage, vector embeddings, and other features. Supabase projects come with PostgreSQL's policy engine for fine-grained user access rules. It has social login integrations with Google, Facebook, GitHub, Azure (Microsoft), Gitlab, Twitter, Discord, and many more. They offer a customizable authentication component for React. Phone login and MFA can be added through third-party SMS providers such as Twilio or Bird. The free tier comes with 50,000 monthly active users. The Pro plan, at $25/month, comes with 100,000 MAUs and $0.00325/MAU beyond that.

Stytch provides a suite of tools designed to simplify authentication, authorization, and security for web and mobile applications. If you're developing an app and need a way for users to log in—whether with passwords, passkeys, or entirely passwordless methods—Stytch offers APIs and SDKs that handle these complexities. Their focus is on making authentication seamless for both developers and end-users while ensuring high security standards. For businesses, particularly B2B SaaS companies, Stytch enables advanced features like multi-tenancy, role-based access control (RBAC), and single sign-on (SSO). They provide an embeddable admin portal, allowing enterprise customers to manage their own authentication configurations, organizational settings, and integrations with identity providers—without constant developer involvement. Stytch places a strong emphasis on scalability and flexibility. Their tools are designed to “just work” across a range of use cases, from simple consumer apps to complex enterprise platforms. Developers can choose how much of the authentication flow they want to control—using pre-built UI components for quick implementation or leveraging headless SDKs and backend APIs for a fully customized experience. Security and fraud prevention are also core to Stytch’s offering. They provide real-time bot detection, device-aware multi-factor authentication, and intelligent rate limiting to protect against credential stuffing and other forms of account abuse. Their infrastructure ensures that login codes and authentication requests are delivered reliably, even when SMS or email providers fail. Stytch supports a broad range of programming languages and frameworks, including Python, Node.js, Java, React, and iOS, making integration into existing tech stacks straightforward. Their platform is designed for developers who want to build secure, user-friendly authentication systems without reinventing the wheel.

Kinde has a generous free plan with up to 10,500 MAU free of charge. Their Pro plan costs $25/month and the price for each additional MAU over 10,500 is $0.0175.

Ory is an API-first identity manager. They offer authentication, analytics, access control, machine-to-machine authentication and more. They have SDKs for the major languages: - Dart - .NET - Elixir - Go - Java - JavaScript - PHP - Python - Ruby - Rust Unfortunately, they don't offer a free tier. Pricing starts at $29/month and includes 1,000 daily active users. Then it's $30 / 1,000 additional DAUs.

Appwrite is an open-source platform for building scalable applications. It comes with authentication, databases, storage, and functions. It's basically a complete development platform. They have an extremely generous free plan with 75,000 MAUs free of charge and their Pro plan is only $15/month. Appwrite offers email and password login, phone auth, magic links, email OTP, anonymous login, JWT login, SSR login, custom tokens, and two-factor authentication.

Formerly known as NextAuth. It's is an open-source authentication library originally built for NextJS. Auth.js is free to use and comes with over 80 integrations for various third-party identity providers such as Google, Facebook, Auth0, Apple etc. You can use it with your own database if you choose to. It works with MySQL, Postgres, MSSQL and MongoDB. Auth.js is compatible with Next.js, SvelteKit and SolidStart as of March 2024.

Keycloak is an open source identity and access management solution. It supports Keycloak single-sign-on and OpenID Connect or SAML 2.0 Identity Providers (Google, Facebook, GitHub etc).

Gluu offers various authentication solutions based on open-source software. There is a self-hosted solution, a managed solution, and a free fully open-source solution based on the Linux Foundation Janssen Project.

Okta is an identity provider for organizations. It offers enterprise solutions for managing workforce and employee identities. It's HIPAA BAA and PCI compliant.

GoPasswordless is an authentication service and SDK that focuses on enabling passwordless authentication flows in web apps.

WADesk is a professional client solution that enables simultaneous logins for multiple WhatsApp accounts, empowering users to seamlessly manage tasks like bulk messaging, number verification, automated conversations, auto-replies, and quick responses. It also facilitates chat message transfer, real-time local backups, rapid export of group members, and monitoring of group messages. Designed for corporate collaboration, WADesk allows employees to share corporate contact details efficiently, enhancing teamwork and productivity across the organization.

Instant credit system integration for Apps and Games with Creduse API. Simplify credit management for your application or game with our developer-friendly API solution. Enjoy quick integration, robust scalability, and comprehensive support, plus powerful analytics to monitor user activity.

📱 Coaches and Personal Trainers: Simplify Your Business Today! Are you tired of managing clients, schedules, and payments? BULK can help you: - Effortless Session Scheduling: No more double bookings. - Instant Client Messaging: Keep all communication in one place. - Secure Payment Processing: Get paid on time, every time. - Content Integration: Easily share Google Docs, Slides, Notion, Zoom links, and more. All this from the convenience of your phone. Available on iOS and Android. Don't overcomplicate this process. Don't use systems with tons of useless features that just bog your progress! Save time, increase efficiency, and watch your business grow! 🎉 Start Your 14-Day FREE TRIAL Now! 🎉

NowKnow helps you get market research done in hours instead of weeks. Ask questions, upload designs, and get thoughtful feedback from AI personas that represent your target audience. Key Features - Fast Results: Get detailed feedback within hours instead of waiting weeks for traditional surveys - Realistic Feedback: AI personas provide authentic responses based on real demographic profiles - Visual Testing: Upload images and designs to get feedback on everything from logos to interfaces - No Privacy Concerns: Since responses come from AI personas, there's no GDPR/CCPA compliance needed Benefits - Test More Ideas: Run multiple studies quickly and affordably - Iterate Freely: Adjust your questions and run new versions instantly - Target Precisely: Get feedback from specific demographic groups - Move Faster: Make informed decisions without long research delays Use Case Test everything from marketing messages to visual designs. Perfect for comparing UI layouts, A/B testing ads, getting feedback on logos, evaluating product mockups, and choosing the best social media content.

Lisapet.ai is the next-level AI product development platform that empowers teams to prototype, test, and ship robust AI features 10x faster. Key Features - Best-in-class AI Playground: Swiftly test and iterate your prompts. Reduce the hassle of prompt prototyping. Our best-in-class AI playground makes the workflow faster, saving you time and effort in designing prompts. - Test-driven prompt engineering: Evalute and measure quality across large data sets. Build a collection of test cases to find the best prompt/model combination across different scenarios Benefits - Save Time: Cut down manual testing and free up your team to focus on shipping features. - Increase Confidence: Automate your testing to ensure reliable AI behavior before deployment. - Optimize Performance: Easily identify the best-performing prompts through side-by-side testing and real-time analytics. - Collaborate Seamlessly: Share progress with stakeholders and incorporate feedback directly within the platform. - Reduce Costs: Monitor token usage and optimize spending with detailed cost breakdowns. Use Case - Rapid Development of AI-Powered Features: Equip your product teams with tools to build, test, and launch AI-powered features without bottlenecks. - Scalable Prompt Engineering: Automate testing and validation to save time and reduce errors in prompt design. - Collaborative Testing: Enable cross-team collaboration by sharing reports and integrating feedback seamlessly.

Wedding Capsule is a digital guestbook and memory collection tool that captures and organizes every special moment from your wedding day. Guests can scan custom-designed QR codes to instantly access the guestbook and share messages, photos, videos, and voice recordings via WhatsApp, Facebook Messenger, or browser—no app required. Contributions are displayed in a beautifully organized timeline, creating a dynamic and interactive keepsake. To make the event even more memorable, guests can participate in fun photo and video missions, while post-wedding reminders ensure no memory is left behind. Key Features - Interactive Guestbook with Timeline: All guest contributions—messages, photos, videos, and voice notes—are displayed in a visually appealing timeline, creating a living memory of the wedding. - Effortless Access with QR Codes: Custom-designed QR codes make it easy for guests to access the guestbook via WhatsApp, Facebook Messenger, or browser. - WhatsApp, Facebook Messenger & Browser Sharing: Guests can upload their memories in one click, with no app download required. - Creative Photo & Video Missions: Fun tasks like “Take a selfie with the couple” or “Film your best dance move” bring energy to the celebration and create unique moments. - Post-Wedding Reminders: Automated follow-ups prompt guests to upload additional photos and videos after the wedding, ensuring a complete collection. - Personal Audio Messages: Guests can leave voice recordings that add a heartfelt, emotional touch to the timeline. Benefits 1. Effortless Memory Collection Collect all messages, photos, videos, and voice notes from guests in one place using WhatsApp, Facebook Messenger, or a browser—no app download needed. 2. A Beautiful, Real-Time Wedding Timeline Display all contributions—text, photos, videos, and voice notes—in a dynamic timeline that tells the full story of your wedding day.

Owlbot offers a cutting-edge AI-powered chatbot service that seamlessly integrates with your data to provide instant responses for you, your customers, or your team. Deploying a tailor-made AI chatbot with Owlbot is straightforward, enhancing both customer service and the efficiency of data analysis with minimal effort. Our AI chatbot is capable of handling 90% of inquiries from customers, clients, or employees effortlessly (>90 languages supported). It can import data from a variety of sources, including documents, markdown files, and webpages, ensuring that you receive precise, immediate answers. Additionally, you can connect the chatbot to your internal tools to access private data in real-time and provide timely responses. You can choose from 12 different large language models (LLMs), such as Mistral, OpenAI, and Anthropic, to find the option that best fits your needs. Owlbot also captures the details of interested visitors, helping you compile a list of potential leads and expand your business opportunities.