The best open source alternative to Fauna is Supabase. If that doesn't suit you, we've compiled a ranked list of other open source Fauna alternatives to help you find a suitable replacement. Other interesting open source alternatives to Fauna are: TiDB, Convex, Instant, and OceanBase.
Fauna alternatives are mainly Backend-as-a-Service (BaaS) Tools but may also be Relational Databases (SQL) or NoSQL & Document Databases. Browse these if you want a narrower list of alternatives or looking for a specific functionality of Fauna.
Provides a full backend stack built on Postgres: authentication, auto-generated APIs, edge functions, realtime subscriptions, file storage, and vector search.

Supabase gives you a production-ready backend without building one from scratch. It's built on Postgres, which means you get a real relational database with full SQL support, not a proprietary data store you'll eventually outgrow. Every project comes with a suite of services that work together out of the box.
The dashboard includes a table editor, SQL editor, and a visual policy builder for row-level security, so you can manage most of your app without leaving the browser. It's aimed at developers who want Firebase-style convenience without giving up SQL or portability.
Compared to alternatives like Appwrite or PocketBase, Supabase leans harder into Postgres as the foundation. That means you can use any Postgres-compatible tool, run raw queries, add extensions, and migrate away if you need to. Self-hosting is supported for teams that need full control over their data.
Supabase holds SOC2 Type 2, HIPAA, and ISO 27001 certifications, which matters for teams building in regulated industries. The free tier is generous enough to prototype and ship small projects without a credit card.
Looking for open source alternatives to other popular services? Check out other posts in the alternatives series and openalternative.co, a directory of open source software with filters for tags and alternatives for easy browsing and discovery.
Distributed SQL database combining OLTP and OLAP capabilities, offering horizontal scalability, high availability, and real-time analytics.

TiDB is a powerful, open-source distributed SQL database that seamlessly combines online transactional processing (OLTP) with online analytical processing (OLAP) workloads. This innovative database solution offers:
TiDB empowers businesses to make data-driven decisions faster, simplify their database infrastructure, and reduce operational costs. Whether you're dealing with large-scale e-commerce, financial services, or IoT data, TiDB provides the performance, scalability, and reliability needed for modern applications.
Open-source reactive database that keeps your web and mobile apps in sync. Write everything in TypeScript with built-in auth, cron jobs, and AI integration.

Build your entire backend in pure TypeScript - from database schemas to queries, authentication to APIs. Your backend code lives alongside your frontend code with full type safety and AI-powered code generation.
Real-time synchronization guaranteed - your app automatically reflects changes to frontend code, backend code, and database state instantly. No need for complex state managers, cache invalidation policies, or manual websocket setup.
Backend essentials built-in - create cron jobs, trigger AI workflows, leverage built-in authentication, and access a growing ecosystem of components that solve common backend needs with simple npm installs.
Developer-friendly features:
Enterprise-ready security with SOC 2 Type II compliance, HIPAA compliance, and GDPR verification. Trusted by developers who want the simplicity of Firebase with the power and flexibility of a modern TypeScript-first platform.
Instant is a database solution for building real-time and offline-enabled applications, simplifying the development of collaborative products.

Instant is a revolutionary database solution designed for developers building real-time and offline-enabled applications. It simplifies the process of creating collaborative products like Notion or Figma by providing a database that can be subscribed to directly in the browser.
Key features and benefits:
Realtime Updates: Instant handles optimistic updates and rollbacks automatically, allowing developers to focus on writing frontend code without worrying about complex backend logic.
Multiplayer Support: Built-in infrastructure for collaborative experiences, including live updates across devices and user accounts.
Offline Mode: Applications built with Instant work seamlessly offline, with local caching and automatic reconciliation when users come back online.
Easy Integration: Developers can write relational queries directly in their app, and Instant takes care of the rest, including servers, auth, permissions, and endpoints.
Scalability: Start without a backend and scale to complex use cases as needed. Instant provides an admin SDK for custom backend logic when required.
Enhanced User Experience: Easily implement features like shared cursors, typing indicators, and presence information with minimal code.
Cross-Platform Compatibility: Works across web and mobile platforms, allowing developers to reuse data logic across different environments.
Instant is backed by Y Combinator and has received praise from industry leaders, including the co-founder of Firebase and engineers from Meta, Stripe, and OpenAI. The team behind Instant consists of senior and staff engineers from Facebook and Airbnb, bringing deep expertise to solve one of the largest problems in frontend development today.
By using Instant, developers can significantly reduce development time and complexity, focusing on building great user experiences rather than dealing with the intricacies of real-time data synchronization and offline support.
Scalable, high-availability database system supporting OLTP, OLAP, and hybrid transactional/analytical processing workloads.

OceanBase is a cutting-edge distributed relational database management system designed to handle massive-scale data processing with unparalleled performance and reliability. Built to meet the demands of modern enterprises, OceanBase offers:
OceanBase's innovative architecture combines the benefits of distributed systems with the familiarity of traditional relational databases, making it an ideal choice for organizations seeking to modernize their data infrastructure while maintaining operational continuity.
A database proxy that enables MongoDB compatibility with PostgreSQL backend, allowing seamless use of MongoDB tools and drivers while avoiding vendor lock-in.

FerretDB is an innovative open-source solution that bridges MongoDB and PostgreSQL, enabling organizations to leverage MongoDB's powerful document database capabilities while using PostgreSQL as the storage backend.
Key benefits include:
FerretDB is ideal for organizations wanting MongoDB-style document database capabilities while maintaining control over their data and infrastructure.