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What should I download?

FlexRule Runtime is the core engine that executes your business logic (rules, flows, and decisions). It is used as a developer SDK to integrate FlexRule into your application and let your application execute business logic models.

FlexRule Designer is an authoring environment that allows you to visually model different types of business logic. You can also validate, simulate and run your processes visually. For this extended functionality, you need to have FlexRule Runtime installed.

FlexRule Server is the server component that hosts your business logic (rules, flows, and decisions) as a REST API. FlexRule Server comes with a Workbench application to help you manage your services.

You can download all of the products via the FlexRule user portal.

What is the .NET Framework Requirement to run FlexRule?

 .Net Framework 4.7.2

What are the Software and Hardware Requirements for different FlexRule Products

FlexRule Designer

These are the minimum requirements to install FlexRule Designer.


  • OS: Windows 10, Windows 11
  • .Net Framework: .NET Framework 4.7.2

If you are using macOS, see the instructions here.


  • CPU: 2 Cores
  • RAM: 8 GB
  • Hard Drive: 14 GB SSD

FlexRule Server On-Prem

These are the minimum requirements to install FlexRule Server.

Windows or Linux

  • OS: Windows 10, Windows 11, Windows Server 2016-R2, Ubuntu
  • Database: 
    • Microsoft SQL Server 2016 OR
    • PostgreSQL
  • .NET Framework: .NET Core 3.1

All .Net Frameworks must be installed on the server.

You can install the FlexRule Server in Linux using Docker Container.

FlexRule Server in the Cloud

  • Cloud Provider
    • Microsoft Azure
    • Amazon AWS
  • Infrastructure:
    • AWS EC2 and ECS
    • Azure Container Services
    • Azure and AWS VM
  • Database Instance or RDS: 
    • Microsoft SQL Server 2016 OR
    • PostgreSQL

FlexRule Server Hardware

  • CPU: 2 Cores
  • RAM: 8 GB
  • Hard Drive: 14 GB SSD

You can install the FlexRule Server using VM, Physical Server, or Docker Container

FlexRule CLI

  • OS: Windows 10, Windows 11, Windows Server 2016, Windows Server 2022

FlexRule Serverless – Decision as a Service

FlexRule models can be deployed directly to a cloud provider as a serverless option.

Serverless deployment of models is supported for the below cloud providers:

  • Azure Function
  • AWS Lambda
  • Google Cloud Function

How do I get FlexRule licenses?

You can download the licenses via the FlexRule user portal.

Can I try sample projects?

Yes – for all the products there are several samples.

FlexRule Runtime samples can be found on GitHub.

FlexRule Designer sample projects can be found right here. Every project contains a downloadable sample, test data, and a video description.
The same sample projects can be downloaded from the home screen of FlexRule Designer.

Your license file needs to be linked to your application so it can use FlexRule Runtime. Follow this link for more details.

How do I integrate FlexRule into my application?

For runtime integration that allows your application to execute logic documents check out our integration section.

How do I create my first rule?

In FlexRule, when you talk about business rules, you can define them in either:

  1. Decision Tables
    Follow this ‘Hello World’ tutorial to start your first decision table.
  2. Natural Language
    Learn how to define business rules in natural language.

How do I bind a model to runtime objects and behaviors?

In FlexRule, Expressions are used to bind the model to runtime behaviors to:

  1. Access object properties.
  2. Call a method on the object.

There are different types of expressions:

  1. Simple expressions (object member access, mathematical operators, etc.).
  2. Monadic operators (processing XML, processing collections, etc.).
  3. Functions that act as global behavior across your logic documents.

How do I connect to a database?

You can use many different data sources as part of your logic.
Follow these instructions to use a database as your data source.

How do I use a conditional if-then-else in a decision table?

In a decision table, columns are AND by setting a hit policy.
By leaving the last row (rule) with no condition you can model the else condition.
Have a look at our Decision Table 101 page for more details.

How do I pass some input values and retrieve results?

Parameters are used to enable communication with logic in different directions (for passing-in values and getting results back).

You can read how to define and manage parameters to find out where to define parameters in FlexRule Designer.

Can I reference my application’s assemblies and use my types in rules?

You can reference your assemblies and use your application’s types to model your logic.

Do this by adding them to the References tab in the Project Properties window in FlexRule Designer.

Read more about managing references in FlexRule Designer here.

I got the “Could not find a part of the path” error when installing the Runtime

Message: Could not find a part of the path 'C:\Users\<LongUserName>\AppData\Local\Pliant Framework\FlexRule Designer.packages\runtime.opensuse.13.2-x64.runtime.native.System.Security.Cryptography.OpenSsl.4.3.0\runtime.opensuse.13.2-x64.runtime.native.System.Security.Cryptography.OpenSsl.4.3.0.nupkg'.

You may get this error if you have a long username on your machine.

How to Solve?

  1. You can contact FlexRule support to manually copy the Runtime folder
    1. Close the opened Designer.
    2. Copy the latest Runtime from C:\Users\<UserName>\Documents\.flexrule provided by FlexRule support team.
    3. Create the folder .flexrule in your Document folder.
    4. Paste the Runtime folder inside your newly created folder.
    5. Restart the Designer.

How about the product and data security compliance?

This article answers the questions on product and data security compliance.

Updated on October 31, 2023

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