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Automation Integration · head to head

Flowable vs NATS

Flowable logo

Flowable

Automation Integration

Apache 2.0 BPMN, CMMN and DMN engine from the team that originally built Activiti

From
Free
Rated
-
Full reviewWebsite
NATS logo

NATS

Databases

High-performance messaging system for cloud-native applications

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Flowable the open source engine is genuinely usable but ships without the modelling studio, work application and admin console, so an open source deployment means building your own user interfaces before anyone can use it.; NATS core NATS has no persistence at all, so messages are lost if no subscriber is listening
  • They diverge on capability: Flowable covers BPMN 2.0 engine, NATS covers Very low latency.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Flowable and NATS actually diverge.

Attributes where Flowable and NATS differ
AttributeFlowableNATS
Pricing modelquoteOpen source, no licence fee
PlatformsLinux, Windows, Docker, Kubernetes, CloudLinux, macOS, Windows, Docker, Kubernetes
CategoryAutomation IntegrationDatabases

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 Flowable

  • BPMN 2.0 engine
  • CMMN case management
  • DMN decision tables
  • Spring Boot integration
  • Modelling studio
  • Task and case application
  • REST APIs
  • History and audit

Only in NATS

  • Very low latency
  • JetStream
  • Single binary
  • Request-reply

What people use each for

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

Flowable

  • An insurer automating claims handling where each case follows a different path and BPMN alone cannot express itnot NATS
  • A bank embedding process orchestration inside an existing Spring Boot estate rather than buying a separate platformnot NATS
  • A team leaving Activiti or jBPM that wants the same API family with active commercial maintenancenot NATS
  • A regulated organisation needing complete process history and decision table audit trails for supervisorsnot NATS

NATS

  • Service-to-service messaging where latency is the binding constraintnot Flowable
  • Edge and IoT messaging where a lightweight broker mattersnot Flowable
  • Replacing a heavier broker when the workload does not need its guaranteesnot Flowable

Where each one falls short

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

Flowable

  • The open source engine is genuinely usable but ships without the modelling studio, work application and admin console, so an open source deployment means building your own user interfaces before anyone can use it.
  • It expects Java engineering capacity; teams looking for a business-user low-code automation tool will find the modelling and deployment cycle far too technical.
  • Enterprise pricing is not published and is quoted per deployment, leaving buyers without a benchmark against Camunda or IBM alternatives.
  • The Activiti fork left three engines with related APIs and overlapping documentation in circulation, and search results routinely return advice for the wrong one.
  • Flowable AG is a small Swiss company relative to its competitors, so the partner network, training market and pool of engineers with production experience are all limited outside Europe.

NATS

  • Core NATS has no persistence at all, so messages are lost if no subscriber is listening
  • JetStream adds the durability but also the operational complexity NATS is chosen to avoid
  • A much smaller ecosystem than Kafka or RabbitMQ, with fewer connectors and integrations
  • Fewer people know it, so hiring and existing organisational knowledge favour the alternatives

Pricing, plan by plan

Flowable

Free
  • Flowable Open SourceFree
    • Apache 2.0 licensed BPMN, CMMN and DMN engines
    • Embeddable Java library or standalone apps
    • No modelling studio or enterprise applications
  • Flowable Enterprise$undefined/year
    • Modelling studio, work application and admin console
    • Connectors, forms and advanced identity management
    • Support with SLA and version maintenance

NATS

Free
  • NATSFree
    • Full functionality
    • No usage limits
    • Community support

Which should you pick?

Choose Flowable if

  • You need bpmn 2.0 engine.
  • You want to start without paying.
  • You work on Linux, Windows, Docker, Kubernetes, Cloud.
  • You also want cmmn case management.
Flowable review

Choose NATS if

  • You need very low latency.
  • You want to start without paying.
  • You work on Linux, macOS, Windows, Docker, Kubernetes.
  • You also want jetstream.
NATS review

Questions people ask

Is Flowable or NATS better?
Neither clearly leads. Flowable starts at Free and NATS at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Flowable or NATS?
Flowable starts at Free and NATS at Free.
Does Flowable or NATS run on more platforms?
Flowable runs on Linux, Windows, Docker, Kubernetes, Cloud. NATS runs on Linux, macOS, Windows, Docker, Kubernetes.
Can I use Flowable for free?
Both have a free tier, so you can try either at no cost before committing.
What is Flowable best used for?
Flowable is most often used for an insurer automating claims handling where each case follows a different path and bpmn alone cannot express it, a bank embedding process orchestration inside an existing spring boot estate rather than buying a separate platform, a team leaving activiti or jbpm that wants the same api family with active commercial maintenance, a regulated organisation needing complete process history and decision table audit trails for supervisors. Of those, an insurer automating claims handling where each case follows a different path and bpmn alone cannot express it and a bank embedding process orchestration inside an existing spring boot estate rather than buying a separate platform are not what NATS is typically brought in for.
What can Flowable do that NATS cannot?
Flowable covers BPMN 2.0 engine, CMMN case management, DMN decision tables, Spring Boot integration. NATS covers Very low latency, JetStream, Single binary, Request-reply.

Answered from the vendors’ own pages

Flowable: Is Flowable open source?

Yes, the BPMN, CMMN and DMN engines are Apache 2.0. The modelling studio and enterprise applications are commercial.

NATS: Is NATS free?

Yes, open source and CNCF-graduated. Synadia sells a managed service.

Flowable: How does it relate to Activiti and jBPM?

The same core developers built jBPM, then Activiti, then forked Activiti in 2016 to create Flowable.

NATS: Does NATS persist messages?

Core NATS does not — it is fire-and-forget. JetStream adds persistence, streaming and replay when you need them.

Flowable: What does Flowable Enterprise cost?

Nothing is published. It is quoted per deployment by the vendor.

NATS: NATS or Kafka?

NATS is far lighter and lower latency, and much simpler to run. Kafka is the answer when you need a durable replayable log and a large connector ecosystem.

Flowable: Why choose it over Camunda?

CMMN case management is a first-class engine, which matters when work is exception-driven rather than a fixed sequence.

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