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Databases · head to head

Azure SQL vs FaunaDB

Azure SQL logo

Azure SQL

Databases

Intelligent, scalable cloud database service from Microsoft

From
Free
Rated
-
Full reviewWebsite
FaunaDB logo

FaunaDB

Databases

Document-relational database whose hosted service closed in 2025 and whose core is now unmaintained Apache 2.0 code.

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Azure SQL ecosystem lock-in limits flexibility compared to open-source or multi-cloud solutions; FaunaDB the hosted service was wound down in 2025, so there is no managed Fauna to buy; every remaining user either operates a JVM cluster themselves or migrates, and both are projects rather than tasks.
  • They diverge on capability: Azure SQL covers Intelligent Performance, FaunaDB covers Document-relational model.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Azure SQL and FaunaDB actually diverge.

Attributes where Azure SQL and FaunaDB differ
AttributeAzure SQLFaunaDB
Pricing modelUnknownfreemium
PlatformsCloud (Microsoft Azure)Web
Founded19752012

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Databases).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Azure SQL

  • Intelligent Performance
  • Advanced Security
  • Hyperscale
  • Serverless Compute
  • Geo-replication
  • Automatic Tuning
  • Built-in AI
  • Power BI

Only in FaunaDB

  • Document-relational model
  • FQL v10
  • Distributed ACID transactions
  • HTTPS access
  • User-defined functions
  • Attribute-based access control
  • Document history
  • Event streaming

What people use each for

The jobs each tool is most often brought in to do.

Azure SQL

  • Transaction processingnot FaunaDB
  • Data storagenot FaunaDB
  • Application backendnot FaunaDB
  • Reportingnot FaunaDB
  • Data analyticsnot FaunaDB

FaunaDB

  • Keeping an existing Fauna-backed application alive on self-hosted infrastructure while a migration is planned and fundednot Azure SQL
  • Extracting historical data from a Fauna dataset that can no longer be reached through the hosted APInot Azure SQL
  • Studying a production implementation of deterministic distributed transactions, since the full server source is now readable under Apache 2.0not Azure SQL
  • Forking the engine deliberately, where an organisation has JVM and distributed-systems staff and wants a document-relational store it fully controlsnot Azure SQL

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Azure SQL

  • Ecosystem lock-in limits flexibility compared to open-source or multi-cloud solutions
  • Managed service reduces control over database configuration and optimization tuning
  • Pricing complexity with consumption-based model can be unpredictable at scale
  • Less operational depth compared to Amazon RDS for advanced scaling scenarios
  • Azure PostgreSQL is less compelling than dedicated PostgreSQL providers outside Azure ecosystem

FaunaDB

  • The hosted service was wound down in 2025, so there is no managed Fauna to buy; every remaining user either operates a JVM cluster themselves or migrates, and both are projects rather than tasks.
  • The open-sourced repository has had no substantive activity since May 2025 and the drivers were frozen alongside it, so you inherit responsibility for security patches in a Scala distributed database that almost nobody else is running.
  • FQL has no wire or dialect compatibility with anything else, so migrating off is a rewrite of every query, index and access rule in the application rather than a data export.
  • No BI tool, ORM or CDC connector speaks FQL, so reporting and analytics always required exporting the data first, and that export tooling is now also unmaintained.
  • The community was small before the shutdown and has dispersed since, so operational answers, tuning advice and people who have run a Fauna cluster in anger are all scarce when something breaks.

Pricing, plan by plan

Azure SQL

Free

No published plan breakdown. See the Azure SQL review.

FaunaDB

Free
  • FreeFree
    • 100K read ops
    • 50K write ops
    • 1GB storage
  • Pro$25/month
    • Pay per use
    • Priority support
    • Advanced features

Which should you pick?

Choose Azure SQL if

  • You need intelligent performance.
  • You want to start without paying.
  • You work on Cloud (Microsoft Azure).
  • You also want advanced security.
Azure SQL review

Choose FaunaDB if

  • You need document-relational model.
  • You want to start without paying.
  • You also want fql v10.
FaunaDB review

Questions people ask

Is Azure SQL or FaunaDB better?
Neither clearly leads. Azure SQL starts at Free and FaunaDB at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Azure SQL or FaunaDB?
Azure SQL starts at Free and FaunaDB at Free.
Does Azure SQL or FaunaDB run on more platforms?
Azure SQL runs on Cloud (Microsoft Azure). FaunaDB runs on Web.
Can I use Azure SQL for free?
Both have a free tier, so you can try either at no cost before committing.
What is Azure SQL best used for?
Azure SQL is most often used for transaction processing, data storage, application backend, reporting. Of those, transaction processing and data storage are not what FaunaDB is typically brought in for.
What can Azure SQL do that FaunaDB cannot?
Azure SQL covers Intelligent Performance, Advanced Security, Hyperscale, Serverless Compute. FaunaDB covers Document-relational model, FQL v10, Distributed ACID transactions, HTTPS access.

Answered from the vendors’ own pages

Azure SQL: Does Azure SQL Database offer a free tier?

Yes, Azure SQL Database includes a permanent free tier that provides 100,000 vCore seconds, 32 GB of data storage, and 32 GB of backup storage per month. This free tier is available for the lifetime of any Azure subscription with no expiration.

Source
FaunaDB: Can I still sign up for Fauna as a service?

No. Fauna Inc. wound down the hosted service in 2025 and the company website is no longer serving. The only way to run Fauna now is to build and operate the open-sourced server yourself.

Azure SQL: What pricing models does Azure SQL Database support?

Azure SQL Database offers consumption-based pricing where you pay for resources used, with no long-term commitments required. Database Savings Plans launched in March 2026 allow committing to a fixed hourly amount and save up to 35% across Azure database services.

Source
FaunaDB: What licence is the open-sourced code under?

Apache 2.0, with the copyright held by a FaunaDB Foundation. That is a permissive OSI licence with no competing-use clause, so you may run it, modify it and even offer it as a service.

Azure SQL: Is Azure SQL Database compatible with on-premises SQL Server?

Yes, Azure SQL Database shares the same Database Engine as on-premises SQL Server. Existing databases maintain their compatibility level and continue to work after upgrades. Azure SQL Managed Instance provides even broader SQL Server compatibility dating back to SQL Server 2008.

Source
FaunaDB: Is the open source version the same software that ran the cloud?

It is the core database engine. The control plane, billing, dashboard and multi-tenant operational tooling that made it a service are not part of the release, so you are running the engine, not the product.

Azure SQL: What high availability features does Azure SQL Database provide?

Azure SQL Database provides automatic backups, geo-replication for disaster recovery, failover groups for automatic failover, and zone redundancy for enhanced availability. The service maintains a 99.99% availability SLA for Business Critical tier.

Source
FaunaDB: What should I migrate to?

There is no drop-in target. Teams that valued the document model with relationships usually land on Postgres with JSONB, and teams that valued the serverless HTTP access pattern usually land on DynamoDB or a managed Postgres with an HTTP driver. Either way the query layer is rewritten.

Azure SQL: Can I use AI features with Azure SQL Database?

Yes, Azure SQL Database includes Copilot for database tasks, Intelligent Applications support, REST API endpoints for building applications, and GraphQL endpoints for modern app development.

Source
FaunaDB: How hard is it to self-host?

It builds as a fat JAR and runs as a multi-node JVM cluster. There is an OPERATING.md, but no supported packaging, no operator, no upstream releases and no support contract, so budget for a distributed-systems engineer, not a container.

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