OSI-licensed open source

Best Open-Source Workflow Platforms and Orchestration Engines (2026)

An open-source workflow platform lets you design, run and monitor multi-step processes on your own infrastructure. Depending on the tool, the workflow might be a business process in BPMN, a data pipeline on a schedule, a durable microservice transaction or an app-to-app automation.

This page is for teams who want a self-hosted engine with source access. The tools split into process engines (Flowable), orchestrators (Airflow, Kestra, Temporal, Conductor, Windmill) and automation builders (Activepieces, Node-RED). Licenses were read from each repo. Camunda 8 and n8n are excluded because they are source-available.

Tools, licences and pricing checked against vendor and repository pages on November 7, 2026.

What to look for

  • •Model: BPMN, DAG, code-defined or visual
  • •Durability and retry semantics
  • •Scheduling, triggers and event support
  • •Scalability and operational footprint
  • •Developer experience and language support
  • •Which features require a paid license

At a glance

ToolBest forPricingLicence
FlowableBusiness process management on JavaFree, open source (self-hosted)Apache-2.0
KestraDeclarative orchestrationFree, open source (self-hosted)Apache-2.0
Apache AirflowData pipelinesFree, open source (self-hosted)Apache-2.0
TemporalDurable microservice workflowsFree, open source (self-hosted)MIT
WindmillScripts to internal tools and workflowsFree, open source (self-hosted)AGPL-3.0
ActivepiecesNo-code app automationFree, open source (self-hosted)MIT
Node-REDIoT and API wiringFree, open source (self-hosted)Apache-2.0
Conductor OSSMicroservice orchestrationFree, open source (self-hosted)Apache-2.0

1. Flowable

Apache-2.0

Best for: Business process management on Java · Free, open source (self-hosted)

Flowable is a BPMN, CMMN and DMN workflow engine for Java, Apache-2.0 licensed.

Strengths

  • + Standards-based
  • + Embeddable

Trade-offs

  • − Java-centric
WebsiteRepository

2. Kestra

Apache-2.0

Best for: Declarative orchestration · Free, open source (self-hosted)

Kestra is an event-driven orchestration platform with declarative YAML flows.

Strengths

  • + YAML flows
  • + Many plugins

Trade-offs

  • − Some features are enterprise-only
WebsiteRepositoryOn TechLogHub

3. Apache Airflow

Apache-2.0

Best for: Data pipelines · Free, open source (self-hosted)

Airflow authors, schedules and monitors workflows as Python DAGs.

Strengths

  • + Mature
  • + Large community

Trade-offs

  • − Not for low-latency event flows
WebsiteRepository

4. Temporal

MIT

Best for: Durable microservice workflows · Free, open source (self-hosted)

Temporal provides durable execution for workflows written in code, MIT licensed.

Strengths

  • + Reliable retries and state
  • + Multi-language SDKs

Trade-offs

  • − Needs engineering investment
WebsiteRepository

5. Windmill

AGPL-3.0

Best for: Scripts to internal tools and workflows · Free, open source (self-hosted)

Windmill turns scripts into workflows and UIs; the repo is mixed Apache-2.0 and AGPL-3.0 with proprietary enterprise features.

Strengths

  • + Code-first
  • + Fast executor

Trade-offs

  • − Mixed licensing
WebsiteRepository

6. Activepieces

MIT

Best for: No-code app automation · Free, open source (self-hosted)

Activepieces is a no-code automation builder with MIT-licensed core.

Strengths

  • + Easy builder
  • + MIT

Trade-offs

  • − Enterprise directories are separately licensed
WebsiteRepository

7. Node-RED

Apache-2.0

Best for: IoT and API wiring · Free, open source (self-hosted)

Node-RED is flow-based programming for wiring devices, APIs and services, from the OpenJS Foundation.

Strengths

  • + Low-code
  • + Foundation-backed

Trade-offs

  • − Large flows get hard to manage
WebsiteRepository

8. Conductor OSS

Apache-2.0

Best for: Microservice orchestration · Free, open source (self-hosted)

Conductor is a microservice orchestration engine for JSON-defined workflows, maintained as an Apache-2.0 community project.

Strengths

  • + Battle-tested
  • + Apache-2.0

Trade-offs

  • − Operational overhead
WebsiteRepository

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How to choose

If you need…Start with
BPMN business processesFlowable
Data pipelinesApache Airflow, Kestra
Durable code workflowsTemporal
Scripts as workflowsWindmill
No-code automationActivepieces
IoT and API flowsNode-RED

Best Open-Source Workflow Platforms and Orchestration Engines: FAQ

Quick answers to common questions

What is a workflow platform?

Software that defines, executes and monitors sequences of tasks.

Is n8n open source?

It is source-available, not OSI open source; we excluded it.

Airflow or Temporal?

Airflow suits scheduled data pipelines; Temporal suits long-running application logic.

Is Camunda open source?

Camunda 8 is source-available; Flowable is an Apache-2.0 alternative.

Related categories

Workflow Automation Platforms for DevelopersAutomated Workflow Software: Best Tools to Automate Business ProcessesBest Workflow Management Software for TeamsOpen-Source Document Workflow Management SoftwareBest Low-Code Open-Source Tools

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