With over 107,000 GitHub stars and adoption by teams at Mozilla, 1Password, Peerlist, and thousands of startups, Supabase has become the most widely deployed open-source Firebase alternative — built entirely on PostgreSQL rather than a proprietary NoSQL store. Every project provisions a dedicated Postgres database with 40+ preinstalled extensions, auto-generating REST APIs via PostgREST, GraphQL via pg_graphql, and real-time change streams via an Elixir-based WebSocket engine that supports database change listeners, user presence tracking, and arbitrary broadcast messaging. Authentication covers email and password, phone OTP, magic links, and 20+ social providers including Google, GitHub, Apple, Azure, and SAML SSO, all enforced through Postgres Row Level Security policies that run inside the database itself. S3-compatible object storage delivers files through a CDN spanning 285+ cities with on-the-fly image transformations powered by imgproxy. Edge Functions run globally distributed TypeScript on the Deno runtime with Node.js compatibility and access to over two million NPM packages. The pgvector extension stores, indexes, and queries vector embeddings for AI-powered semantic search and retrieval-augmented generation workflows. Supabase Studio provides a browser-based dashboard with a table editor, SQL editor, schema visualizer, and log explorer. Official client SDKs ship for JavaScript, Python, Flutter, Swift, Kotlin, C#, Go, and Ruby. The self-hosted Docker Compose stack runs fourteen coordinated services including Kong API gateway, Supavisor connection pooler, and Logflare analytics. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache 2.0 licensed.

With over 14,000 GitHub stars, 1 million managed identities on Logto Cloud, and continuous releases through version 1.42.0 in July 2026, Logto has emerged as the most credible open-source alternative to Auth0, Clerk, and AWS Cognito by packaging OIDC, OAuth 2.1, enterprise SSO, multi-tenancy, and RBAC into a single MPL-2.0 codebase that self-hosts for free with no per-MAU pricing surprises. Every Logto tenant operates as a fully compliant OpenID Provider supporting PKCE-only public clients, DPoP token binding, and RFC 9068 JWT access tokens. Pre-built sign-in flows handle email, phone, social login via Google, Facebook, Azure AD, and dozens of connectors, passkey authentication, and multi-factor verification through TOTP and WebAuthn. Organizations enable first-class multi-tenancy where users belong to multiple tenants with per-organization RBAC scopes on API resources. Enterprise SSO connects to Okta, Entra ID, and any SAML or OIDC identity provider. SDKs for over 30 frameworks including React, Next.js, Angular, Vue, Flutter, Go, and Python integrate authentication into SPAs, web apps, mobile apps, APIs, machine-to-machine, and CLI tools. The admin console provides user management, audit logs, webhook event subscriptions, and custom domain configuration. Personal Access Tokens and token exchange support AI agent architectures and MCP server authentication. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MPL-2.0 licensed.

With over 330 GitHub stars and described as "OpenRouter, but for agent tools instead of models," Treg is the unified tool registry that gives your AI agent one base URL, one token, and instant access to approximately 2,800 cataloged endpoints across 56 providers — SEO and backlink analysis via Semrush and Moz, social media intelligence from TikTok and Instagram, people and company enrichment through Crunchbase and Hunter, media buying, scraping, and SERP data — all priced per call from fractions of a cent with no provider signup required. The FastAPI backend with PostgreSQL stores credential bindings and injects them server-side into every proxied request, ensuring API keys and OAuth tokens never touch the agent or local machine while every call is audit-logged. Teams register their own paid API accounts, OAuth connections, vendor CLIs like Stripe, GitHub CLI, Vercel, and gcloud, plus custom SKILL.md definitions — all callable by every teammate's agent through a single treg token with automatic credential injection. The evidence-based tool selector shows success rate, response speed, and last-seen timestamp for each provider, so agents pick tools on measured performance rather than guesswork. Bring-your-own-key routes bypass metering entirely, and the one-dollar free credit on every new team lets agents start calling immediately. The Vue.js web dashboard provides team management, audit logs, catalog browsing, and guided onboarding. Self-host with pip install tools-registry[server] on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

With 13,800+ GitHub stars and active releases through 2026, Casdoor is the open-source identity platform that ships OAuth 2.0, OIDC, SAML 2.0, CAS, LDAP, SCIM 2.0, WebAuthn passkeys, TOTP multi-factor authentication, and Face ID biometric login in a single Go binary with a React web console — covering every authentication protocol your organization will ever need. Social login connects 50+ identity providers including Google, GitHub, Microsoft Azure AD, Facebook, WeChat, DingTalk, Apple, Twitter, and LinkedIn without custom code. The AI-first architecture includes a Model Context Protocol gateway for AI agent authentication and Agent-to-Agent protocol support for securing LLM-powered workflows. Built-in Casbin integration delivers authorization primitives beyond basic RBAC: attribute-based access control, relationship-based access control, and custom policy models through a unified engine. The organization-scoped multi-tenancy model isolates users, applications, and identity providers per tenant with customizable login pages, branding, and SMTP configuration. SCIM 2.0 endpoints automate user provisioning from HR systems and Active Directory. Official SDKs for Go, Java, Node.js, Python, and PHP accelerate application integration. The RESTful API exposes every resource for programmatic management. Comprehensive audit logs record authentication events and administrative actions. Deploy via Docker Compose with MySQL or PostgreSQL, the all-in-one SQLite Docker image for quick trials, or the official Kubernetes Helm chart for production clusters. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache 2.0 licensed.

With over 24,000 GitHub stars and a rapidly growing community of self-hosters, authentik delivers enterprise-grade identity management that replaces commercial solutions like Okta and Auth0 with a fully self-hosted platform requiring no per-user licensing fees. The platform serves as a unified identity provider supporting SAML 2.0, OAuth 2.0 and OpenID Connect, LDAP for legacy application compatibility, SCIM 2.0 for automated user provisioning, and RADIUS for network device authentication. The visual flow designer enables administrators to create custom authentication workflows combining password verification, multi-factor authentication with TOTP, WebAuthn, and SMS codes, email verification, captcha challenges, and conditional logic based on user attributes or device context. The forward-auth and reverse proxy integration works seamlessly with Traefik, Nginx, Caddy, and Envoy to protect applications that lack built-in authentication. User enrollment flows support self-registration with configurable approval workflows, invitation links, and automatic group assignment. The LDAP outpost exposes user and group data to legacy applications requiring LDAP bind authentication, while the SCIM provider automates user lifecycle management with downstream applications. Multi-tenancy support through brands allows a single authentik instance to serve multiple organizations with independent domains, branding, and authentication policies. The admin interface provides comprehensive user management, group hierarchy, application catalog, event logging with GeoIP enrichment, and system health monitoring. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Licensed under a source-available license with an open-source community edition.

The integrations your SaaS product offers its own users - that is what Nango, an open-source product-integrations platform, exists to build. It solves the repetitive infrastructure work behind every third-party API connection: OAuth flows, API key handling, token refresh, encrypted credential storage, rate-limit backoff, retries, and multi-tenant connection management. It ships pre-built auth configurations for 800+ APIs. Your users connect their accounts through an embeddable, white-label Connect UI, and your backend then reads or writes data through Nango's proxy, SDKs, or REST API without ever touching raw credentials. Integration logic is written as TypeScript functions covering actions, scheduled data syncs, and webhook processing - all running on one runtime with retries, checkpointing, and per-connection logs built in. Syncs pull records incrementally on a schedule, one-way or two-way, which suits RAG pipelines, search indexing, and keeping local copies of external data current. Selected actions can also be exposed as tool schemas or through a built-in MCP server, so AI agents operate on user-connected accounts without ever handling provider credentials. Auth support spans OAuth 2.0, OAuth 1.0a, API keys, basic auth, and JWT, and observability - logs, metrics, failure detection, and a reconnect flow for expired credentials - is scoped per customer connection for easier support debugging. Works with any backend language. Self-hosting on RepoCloud keeps all customer credentials and synced data on infrastructure you control, which matters for data residency and compliance requirements.

Backed by over 56,000 GitHub stars and a growing ecosystem of client and server SDKs covering Flutter, React Native, Swift, Kotlin, Python, Node.js, Deno, and more, Appwrite provides a complete backend platform that replaces Firebase and Supabase with a fully self-hostable architecture. The authentication module supports email and password, phone OTP, magic links, OAuth providers including Google, GitHub, Apple, and Facebook, anonymous sessions, and JWT token management with configurable session policies. The database service provides a document-oriented store with collections, indexes, query filters, pagination, and real-time subscriptions that push changes to connected clients instantly via WebSocket. The storage service handles file uploads with built-in image manipulation including cropping, resizing, format conversion, and compression, served through a CDN-ready URL structure. Serverless functions execute custom backend logic triggered by HTTP requests, scheduled cron jobs, or database events, with runtime support for Node.js, Python, PHP, Ruby, Dart, Swift, Kotlin, and Java. The messaging service enables push notifications, SMS, and email delivery through configurable providers including APNS, FCM, Twilio, Vonage, Mailgun, and Sendgrid. Team management with role-based permissions, webhook integrations, and health monitoring APIs complete the platform. The admin console provides a web-based dashboard for managing all services, monitoring usage metrics, and configuring project settings. Deployment runs via Docker Compose with MariaDB for metadata and configurable storage adapters. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. BSD 3-Clause licensed.

Backed by over 8,700 GitHub stars and OpenID Connect certification, Pocket ID delivers what enterprise identity platforms like Keycloak provide but without the configuration complexity — a passkey-only OIDC provider purpose-built for homelabs and small deployments. The core design decision is radical simplicity: no passwords exist in the system, only WebAuthn-based passkeys using hardware security keys, TouchID, FaceID, or device PINs, making phishing attacks structurally impossible rather than merely discouraged. The Go backend built on the Gin framework serves a compiled SvelteKit frontend as static assets, running as a single Docker container with SQLite as the default database and optional PostgreSQL for larger deployments. User management supports manual creation, signup links, and open registration, with group-based access control that restricts which OIDC clients each group can access and attaches custom claims for downstream role mapping. LDAP synchronization pulls users and groups from OpenLDAP or Active Directory, while SCIM support enables automated provisioning from compatible identity sources. Federated client credentials handle machine-to-machine authentication for service-to-service communication patterns. The audit system logs every authentication event with GeoIP enrichment, sends email notifications for sign-ins from unknown devices, and provides one-time login codes for accessing accounts from devices without passkey support. TLS with HTTP/2 is built in, PKCE adds code exchange protection, and OpenTelemetry provides tracing and metrics integration. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. BSD 2-Clause licensed.

Backed by 9,200 GitHub stars and venture funding led by Nauta Capital, Nhost is the open-source Firebase alternative that replaces Google's proprietary document store with a relational PostgreSQL foundation from day one. The Hasura integration auto-generates a real-time GraphQL API with subscriptions, role-based permissions, and remote schemas from your PostgreSQL tables, while event triggers and cron triggers automate backend workflows without custom infrastructure. Authentication supports email and password, magic links, phone OTP via SMS, social OAuth providers including Google and GitHub, WebAuthn for passwordless login with Face ID, fingerprints, and YubiKeys, plus two-factor authentication. Since the Q1 2026 release, Nhost Auth also functions as a full OAuth2 and OpenID Connect provider, allowing your Nhost project to issue tokens to third-party applications the same way GitHub or Google do. The S3-compatible storage service handles file uploads with automatic image optimization, virus scanning, and presigned URLs for secure direct downloads. Node.js serverless functions deploy JavaScript and TypeScript backend logic without managing servers, while the Nhost CLI spins up the complete local stack via Docker for development with automatic database migration tracking and Hasura metadata management. The MCP server integration exposes project documentation and data schemas to AI assistants for intelligent query building. SDKs cover JavaScript, TypeScript, React, Vue, Next.js, and Dart for Flutter. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Securing a SaaS product, running B2B onboarding, or replacing Auth0 and Keycloak with a stack they own - teams needing more than basic auth reach for ZITADEL, an open-source identity and access management platform built in Go. Its multi-tenancy model is the differentiator: a strict Instance, Organization, Project hierarchy isolates data and scopes policy at each level, with identity brokering (pre-built templates for Google, GitHub, Microsoft, Apple, plus generic OIDC, OAuth, SAML, and LDAP), domain discovery that routes users to the right organization by email domain, and delegated management so customers administer their own users and roles. Authentication covers OpenID Connect (certified, including device authorization and token exchange), SAML 2.0 as both IdP and SP, SCIM, FIDO2 passkeys for phishing-resistant passwordless login, and MFA via OTP, email, SMS, and U2F; machine-to-machine flows support JWT profile, PATs, and client credentials. The architecture is event-sourced - every mutation is an immutable event, yielding a complete audit trail - with relational projections for queries and no external session store, so it scales horizontally. API-first with gRPC and REST, extensible via Actions webhooks, and the same codebase self-hosted (Docker Compose or Helm on PostgreSQL) as in the cloud.

The Bitwarden server, reimplemented in Rust: Vaultwarden (formerly bitwarden_rs) is the unofficial lightweight edition. It speaks the same wire protocol as the official server, so every official Bitwarden client - browser extensions, iOS, Android, desktop, and the bw CLI - connects without modification, while the server itself runs as a single container against SQLite (or MySQL/MariaDB/PostgreSQL) instead of the official multi-container stack that wants gigabytes of RAM. Features Bitwarden gates behind paid tiers ship free: organizations with collections, groups, member roles, and policies; TOTP code storage; file attachments; Bitwarden Send; Emergency Access; event logs; and admin password reset. Two-factor options cover authenticator apps, email, FIDO2 WebAuthn, YubiKey, and Duo, and OIDC-based SSO landed natively in v1.35.0. Zero-knowledge encryption is unchanged - vault data is encrypted client-side and the master password never reaches the server. Attachments and Sends store on local disk or S3-compatible backends, an admin panel manages users and server settings, and backup is copying one data directory. Suited to individuals and teams up to roughly 50 users.

An entire backend in a single Go executable: PocketBase embeds SQLite with realtime subscriptions, authentication and user management, file storage, and an admin dashboard, all behind a REST-ish API. SQLite runs in WAL mode, which outperforms client-server databases for the read-heavy workloads typical of small and mid-sized apps. Authentication supports email/password, one-time passwords, and 15+ OAuth2 providers including Google, Apple, and GitHub, with stateless tokens. Clients subscribe to record changes over server-sent events, and official JavaScript and Dart SDKs cover web, mobile, and Flutter frontends. Collections, rules, and API access permissions are managed visually in the admin UI. When you need custom logic, extend it with JavaScript hooks running in the embedded JS VM of the prebuilt binary, or import PocketBase as a Go library and compile custom business logic into your own single-file backend. File storage attaches uploads to records with thumbnail generation for images and optional S3-compatible external storage. All state lives in one pb_data directory, so backup is a directory copy and upgrade is replacing a binary - one of the lowest-maintenance backends you can run. The contrast with Firebase is the point: where usage-based pricing scales with reads, writes, and bandwidth, PocketBase runs the entire backend at flat hosting cost, and the data is a plain SQLite file you can copy anywhere. MIT-licensed.

Your users belong in your own database - Authorizer, an open-source authentication and authorization server shipping as a single Go binary, keeps them there. It connects to 13+ backends - PostgreSQL, MySQL, SQLite, SQL Server, MariaDB, MongoDB, Cassandra, ScyllaDB, ArangoDB, DynamoDB, Couchbase, YugabyteDB, PlanetScale, and CockroachDB - so identity data lives beside the application it protects instead of in an auth vendor's cloud. The server is fully OAuth 2.0 and OpenID Connect compliant, including authorization code flow with PKCE, a JWKS endpoint, token revocation, and nine JWT signing algorithms. Login options cover email/password, magic links, TOTP multi-factor, SMS OTP via Twilio, and social providers including Google, GitHub, Apple, Microsoft, and Discord. Authorization goes beyond roles: an embedded OpenFGA engine provides Zanzibar-style relationship-based permission checks in process. APIs are exposed over GraphQL, REST, and gRPC, with SDKs for JavaScript, React, Go, and Python, plus themeable built-in login pages and an admin dashboard. Apache 2.0 licensed.

Authentication that lives inside your application rather than behind a redirect to an external identity provider - SuperTokens takes a fundamentally different architecture from Auth0 and AWS Cognito. Three tiers make that work - frontend SDKs (React, Angular, Vue, vanilla JS, React Native) render overridable login UI and manage tokens; backend SDKs (Node.js, Python, Go) expose auth endpoints on your own API domain; and SuperTokens Core, the piece you host here, is the stateless HTTP service handling core auth logic, password hashing, token signing, and database operations against PostgreSQL. The recipe system keeps features decoupled: use email/password, social login, passwordless (magic links, OTP), phone-password, multi-factor authentication (TOTP, WebAuthn), user roles, and microservice auth - individually or combined; you can even use SuperTokens purely for session management alongside another login provider. Sessions are where it shines: rotating refresh tokens with theft detection, automatic access-token refresh, CSRF protection, and secure cookie handling out of the box - the details that become vulnerabilities when hand-rolled. Verification happens locally in your backend via cached JWT signing keys, so the Core stays off the hot path. Self-hosted means no user limits, free forever, with all user data in your database. Apache-licensed.

With 12,600 GitHub stars and 52 releases in under a year of development, InsForge is the fastest-growing open-source backend platform purpose-built for AI coding agents — giving Claude, Cursor, and any MCP-compatible tool direct access to database, authentication, storage, compute, and AI model infrastructure through a single self-hosted stack. The native MCP server exposes every InsForge operation as callable tools, letting coding agents autonomously create database tables, manage user authentication, upload files, deploy edge functions, and ship complete full-stack applications without human intervention. The Model Gateway provides an OpenAI-compatible API that routes requests across multiple LLM providers (OpenAI, Anthropic, Google, and open-source models) with unified billing, rate limiting, and fallback logic. PostgreSQL with pgvector handles both relational data and vector embeddings for RAG pipelines, while S3-compatible storage manages file uploads and static assets. Edge Functions run serverless TypeScript code on Deno with sub-millisecond cold starts for API endpoints, webhooks, and scheduled tasks. The authentication system provides user management, OAuth2 flows, sessions, and magic links with JWT token handling built in. Site Deployment builds and serves frontend applications with automatic SSL and custom domain configuration. The CLI paired with Agent Skills enables terminal-based workflows where agents invoke InsForge operations directly from the command line. Deploy via Docker with PostgreSQL as the only required external dependency. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

Backed by 9,000+ GitHub stars and developed by a Germany-based team with deep FIDO2 expertise, Hanko delivers the open-source authentication platform that replaces Auth0, Clerk, and Firebase Auth with a passkey-first architecture built on phishing-resistant WebAuthn credentials. The Go backend exposes both public and administrative HTTP APIs handling passkey registration and login, password authentication, email passcodes, TOTP-based MFA, security key verification, server-side sessions with remote revocation, and JWT issuing with configurable expiry and refresh policies. OAuth SSO connects Apple, Google, GitHub, Microsoft, and custom OIDC providers, while SAML Enterprise SSO integrates corporate identity providers for single sign-on across the organization. Hanko Elements provides framework-agnostic web components that embed complete onboarding, login, and user profile flows into any application with two lines of code, fully customizable via CSS variables and supporting i18n with custom translations. The JavaScript frontend SDK handles API communication, credential management, and session state for teams building custom authentication UIs without the pre-built components. Webhooks notify external services of authentication events including user creation, login, email verification, and password changes. Privacy-first design principles enforce data minimalism with user-deletable passwords and configurable identifier strategies supporting email-only, username-only, or combined approaches. Docker deployment starts the backend with PostgreSQL or MySQL, serving both APIs on configurable ports. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 (backend) / MIT (frontend) licensed.

With 13,800 GitHub stars, adoption by OpenAI for ChatGPT's authentication infrastructure serving 800 million weekly active users, and governance under the Ory open-source ecosystem, Ory Kratos provides enterprise-grade identity management as a headless API server that separates authentication logic from user interface — enabling any frontend framework to consume standardized self-service flows for registration, login, recovery, verification, and profile management. Multi-factor authentication supports passkeys, WebAuthn security keys, TOTP authenticator apps, SMS one-time codes, email magic links, and backup recovery codes with configurable Authenticator Assurance Levels enforcing step-up authentication for sensitive operations. Social sign-in connects to any OpenID Connect provider including Google, GitHub, Apple, and Microsoft, plus enterprise SAML 2.0 federation for B2B single sign-on. Customizable identity schemas using JSON Schema define user profiles with flexible trait structures, while pre- and post-flow webhooks enable integration with CRMs, analytics, and compliance systems. The courier system handles email and SMS delivery for verification codes and password recovery links. Session management provides device tracking, forced logout, and configurable lifespans with privileged session elevation. Deploy alongside Ory Hydra for OAuth2/OIDC token issuance and Ory Keto for fine-grained permissions to build a complete identity platform. Docker Compose deployment with PostgreSQL. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache 2.0 licensed.