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Databases · head to head

Amazon RDS vs EMQX

Amazon RDS logo

Amazon RDS

Databases

Set up, operate, and scale a relational database in the cloud

From
Free
Rated
-
Full reviewWebsite
EMQX logo

EMQX

Databases

Erlang MQTT broker for large IoT fleets, relicensed to BSL with production free use limited to one node

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Amazon RDS no super-user access or direct host connectivity limits advanced customization; EMQX the move to Business Source Licence 1.1 at version 5.9 in May 2025 limits free production use to a single node, so the clustering that justifies choosing EMQX now requires a paid subscription from the second node onward.
  • They diverge on capability: Amazon RDS covers Multiple DB Engines, EMQX covers Erlang clustering.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Amazon RDS and EMQX actually diverge.

Attributes where Amazon RDS and EMQX differ
AttributeAmazon RDSEMQX
Pricing modelusage-basedPer month by connection and session volume
PlatformsAWS Cloud, Multi-AZ, Multi-regionLinux, Docker, Kubernetes, Cloud, macOS
Founded2006Unknown

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 Amazon RDS

  • Multiple DB Engines
  • Automated Backups
  • Multi-AZ Deployment
  • Read Replicas
  • Encryption
  • Performance Insights
  • Automatic Scaling
  • MySQL

Only in EMQX

  • Erlang clustering
  • MQTT 5.0 and QUIC
  • Rule engine
  • Data integration sinks
  • Session persistence
  • Multi protocol gateways
  • Authentication and authorisation
  • Dashboard and REST API

What people use each for

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

Amazon RDS

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

EMQX

  • A connected vehicle platform needing millions of persistent MQTT sessions with QUIC for handover across mobile networksnot Amazon RDS
  • An industrial operator routing sensor telemetry straight into TimescaleDB or Kafka without writing a consumer servicenot Amazon RDS
  • An IoT product team that has outgrown a single Mosquitto instance and needs clustering and shared subscriptionsnot Amazon RDS
  • A smart building deployment mixing MQTT, CoAP and LwM2M devices on one brokernot Amazon RDS

Where each one falls short

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

Amazon RDS

  • No super-user access or direct host connectivity limits advanced customization
  • Pricing unpredictable and expensive compared to GCP alternatives with equivalent features
  • Limited access to system procedures and tables requiring advanced permissions
  • No Oracle RAC (Real Application Clusters) support for high-availability Oracle deployments

EMQX

  • The move to Business Source Licence 1.1 at version 5.9 in May 2025 limits free production use to a single node, so the clustering that justifies choosing EMQX now requires a paid subscription from the second node onward.
  • The relicensing arrived in a minor release, which caught users who had pinned to 5.x expecting Apache 2.0 terms and forced legal review of existing deployments.
  • Running an Erlang/OTP cluster well requires operational knowledge most teams do not have, and diagnosing distribution, mnesia or memory issues means learning a runtime you use for nothing else.
  • Enterprise pricing is quoted rather than published for the self-managed edition, so the cost of the clustered configuration you actually need is invisible until you talk to sales.
  • The Serverless tier caps at around a thousand connections and shares infrastructure, which makes it a prototyping tier rather than a genuine small production option.

Pricing, plan by plan

Amazon RDS

Free
  • On-Demand Instances$undefined/per second
  • Reserved Instances$undefined/mo
  • Database Savings Plans$undefined/mo

EMQX

Free
  • Open Source single nodeFree
    • BSL 1.1 licence since version 5.9
    • Free production use of one node only
    • All former enterprise features visible
  • ServerlessFree
    • Free monthly quota then pay as you go
    • Up to 1,000 connections
    • 8 by 5 support
  • Dedicated Flex$234/month
    • Single tenant cluster
    • Traffic allowance included
    • 24/7 support
  • Enterprise self-managed$undefined/year
    • Deploy on premises, at the edge or in any cloud
    • Clustering licensed
    • 256 MB maximum message size

Which should you pick?

Choose Amazon RDS if

  • You need multiple db engines.
  • You want to start without paying.
  • You work on AWS Cloud, Multi-AZ, Multi-region.
  • You also want automated backups.
Amazon RDS review

Choose EMQX if

  • You need erlang clustering.
  • You want to start without paying.
  • You work on Linux, Docker, Kubernetes, Cloud, macOS.
  • You also want mqtt 5.0 and quic.
EMQX review

Questions people ask

Is Amazon RDS or EMQX better?
Neither clearly leads. Amazon RDS starts at Free and EMQX at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Amazon RDS or EMQX?
Amazon RDS starts at Free and EMQX at Free.
Does Amazon RDS or EMQX run on more platforms?
Amazon RDS runs on AWS Cloud, Multi-AZ, Multi-region. EMQX runs on Linux, Docker, Kubernetes, Cloud, macOS.
Can I use Amazon RDS for free?
Both have a free tier, so you can try either at no cost before committing.
What is Amazon RDS best used for?
Amazon RDS is most often used for transaction processing, data storage, application backend, reporting. Of those, transaction processing and data storage are not what EMQX is typically brought in for.
What can Amazon RDS do that EMQX cannot?
Amazon RDS covers Multiple DB Engines, Automated Backups, Multi-AZ Deployment, Read Replicas. EMQX covers Erlang clustering, MQTT 5.0 and QUIC, Rule engine, Data integration sinks.

Answered from the vendors’ own pages

Amazon RDS: What is included in the AWS Free Tier for RDS?

For signups before July 15, 2025: 750 hours per month of single-AZ database instance usage (12 months), 20 GB General Purpose SSD storage monthly, 20 GB automated backup storage monthly, available engines include MySQL, MariaDB, PostgreSQL, SQL Server Express Edition. For signups after July 15, 2025: choice between Free Plan or Paid Plan, $100 in credits plus up to $100 additional credits for activating foundational services, credits valid 12 months. Free Tier unavailable in AWS GovCloud (US) and China (Beijing) regions.

Source
EMQX: Is EMQX still open source?

Not in the OSI sense since version 5.9. It is source-available under Business Source Licence 1.1, reverting to Apache 2.0 four years after each release.

Amazon RDS: How is data transfer priced in RDS?

Same Availability Zone (EC2 to RDS) is free. Multi-AZ replication is free. Cross-AZ within same region is 0.01 USD per GB in and out. Cross-region snapshots and backups follow standard data transfer charges.

Source
EMQX: Can I run a free cluster?

No. The additional use grant permits free production use of one node; clustering requires a commercial licence.

Amazon RDS: What database engines are supported by RDS?

Aurora, MySQL, PostgreSQL, MariaDB, Oracle, SQL Server, and IBM Db2. Pricing varies by engine.

Source
EMQX: What changed for existing users?

Community and enterprise editions merged, so all features are now visible, but the licence terms tightened in the same minor release.

Amazon RDS: What cost components are included in RDS monthly pricing?

DB instance hours (billed in 1-second increments, 10-minute minimum), storage per GB per month, I/O requests (Aurora and magnetic storage only), provisioned IOPS per month, backup storage, and data transfer fees.

Source
EMQX: Which version is still Apache 2.0?

Releases before 5.9 remain under Apache 2.0, and each BSL release converts to Apache 2.0 four years after publication.

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