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Cloud · head to head

Lambda (AWS Serverless) vs FaunaDB

Lambda (AWS Serverless) logo

Lambda (AWS Serverless)

Cloud

Run code without thinking about servers

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: Lambda (AWS Serverless) billed on two axes at once, $0.20 per million requests plus $0.0000166667 per GB-second of duration, so memory settings change the bill as much as traffic does; 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: Lambda (AWS Serverless) covers Function-as-a-Service, FaunaDB covers Document-relational model.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Lambda (AWS Serverless) and FaunaDB actually diverge.

Attributes where Lambda (AWS Serverless) and FaunaDB differ
AttributeLambda (AWS Serverless)FaunaDB
Pricing modelusage-basedfreemium
PlatformsWeb, ApiWeb
CategoryCloudDatabases
Founded20142012

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

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 Lambda (AWS Serverless)

  • Function-as-a-Service
  • Event-driven execution
  • Auto-scaling
  • Pay-per-use
  • Multiple languages
  • Concurrency limits
  • Dead Letter Queues
  • Environment variables

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.

Lambda (AWS Serverless)

  • Event-driven functions without managing serversnot FaunaDB
  • API backends behind API Gatewaynot FaunaDB
  • Processing S3, DynamoDB, SQS and Kinesis eventsnot FaunaDB
  • Scheduled jobs without a always-on instancenot FaunaDB
  • Edge compute through Lambda@Edgenot FaunaDB

FaunaDB

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

Where each one falls short

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

Lambda (AWS Serverless)

  • Billed on two axes at once, $0.20 per million requests plus $0.0000166667 per GB-second of duration, so memory settings change the bill as much as traffic does
  • Provisioned concurrency, used to avoid cold starts, is charged separately at $0.0000041667 per GB-second whether or not the function runs
  • Ephemeral storage beyond the included 512 MB is metered
  • Lambda@Edge costs $0.60 per million requests, three times the standard request rate
  • VPC use and cross-region data transfer carry EC2 charges on top

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

Lambda (AWS Serverless)

Free
  • Free TierFree
    • 1M free requests/month
    • 400,000 GB-seconds/month
    • Always free

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 Lambda (AWS Serverless) if

  • You need function-as-a-service.
  • You want to start without paying.
  • You work on Web, Api.
  • You also want event-driven execution.
Lambda (AWS Serverless) 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 Lambda (AWS Serverless) or FaunaDB better?
Neither clearly leads. Lambda (AWS Serverless) 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, Lambda (AWS Serverless) or FaunaDB?
Lambda (AWS Serverless) starts at Free and FaunaDB at Free.
Does Lambda (AWS Serverless) or FaunaDB run on more platforms?
Lambda (AWS Serverless) runs on Web, Api. FaunaDB runs on Web.
Can I use Lambda (AWS Serverless) for free?
Both have a free tier, so you can try either at no cost before committing.
What is Lambda (AWS Serverless) best used for?
Lambda (AWS Serverless) is most often used for event-driven functions without managing servers, api backends behind api gateway, processing s3, dynamodb, sqs and kinesis events, scheduled jobs without a always-on instance. Of those, event-driven functions without managing servers and api backends behind api gateway are not what FaunaDB is typically brought in for.
What can Lambda (AWS Serverless) do that FaunaDB cannot?
Lambda (AWS Serverless) covers Function-as-a-Service, Event-driven execution, Auto-scaling, Pay-per-use. FaunaDB covers Document-relational model, FQL v10, Distributed ACID transactions, HTTPS access.

Answered from the vendors’ own pages

Lambda (AWS Serverless): Is there a free tier for AWS Lambda?

Yes. AWS Lambda offers a free tier including 1 million requests per month, 400,000 GB-seconds per month, and 100 GB monthly response streaming.

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.

Lambda (AWS Serverless): How is AWS Lambda charged?

Lambda charges $0.20 per million requests. Duration charges are $0.0000166667 per GB-second for x86 (up to 6 billion GB-seconds/month in US East Ohio with tiered pricing). Ephemeral storage over the included 512 MB costs $0.0000000309 per GB-second. Provisioned Concurrency costs $0.0000041667 per GB-second with a 5-minute minimum.

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.

Lambda (AWS Serverless): What are Lambda Durable Functions pricing?

Lambda Durable Functions include operations at $8.00 per million (start execution, steps, waits). Data written costs $0.25 per GB. Data retention is $0.15 per GB-month with configurable 1-90 day retention (default 14 days).

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.

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.

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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