Rule Engine Tester

Test a set of if-then business rules free online against your input data. Real rule evaluation engine showing which rules match and which action fires first.

Rules (evaluated top to bottom, first match wins)

Browser only -- real first-match-wins rule evaluation.

How to Use This Tool

1
Define input variablesYour test data
2
List rules with conditions and actionsIn priority order
3
See which rule fires firstReal first-match-wins evaluation

First-Match-Wins -- The Convention That Makes Order Matter

This evaluates your rules in the exact order listed, firing whichever rule's condition matches first and stopping there -- the same convention many production rule engines use. This means rule order is a genuinely meaningful part of the logic, not just an organizational preference.

Why Overlapping Conditions Create Subtle Bugs

Two rules might both technically match the same input data, but only the first one listed actually fires its action. Reordering rules, or adding a new rule without considering where it lands relative to existing ones, can silently change which outcome actually occurs -- exactly the kind of issue testing against real sample data helps surface before it causes a real problem.

Related Tools You Might Like

Condition Evaluator
Condition Evaluator
JSON Object Comparer
JSON Object Comparer
LINQ Query Explainer
LINQ Query Explainer
C# Expression Playground
C# Expression Playground
Formula Evaluator
Formula Evaluator
Workflow State Machine Simulator
Workflow State Machine Simulator

Frequently Asked Questions

A rule engine evaluates a set of if-then rules against input data, firing the action for whichever rule's condition matches -- common in business logic for pricing, eligibility, or approval workflows. Testing rules against sample data before deploying them helps catch logic errors or unintended overlaps.
Rules are evaluated in the order you list them, and the first matching rule's action fires -- the same first-match-wins convention many real rule engines use, making rule order itself a meaningful part of the logic.
Two rules with overlapping conditions can produce very different outcomes depending on which is listed first, since only the first match actually fires -- a common source of subtle bugs when rules are added or reordered without considering this interaction.
Yes, editing either your rules or your input data and re-running shows immediately how the outcome changes, letting you compare different rule orderings or different input scenarios side by side.
Discount eligibility based on customer attributes, loan approval logic based on multiple criteria, or shipping cost tiers based on order characteristics are all common real-world rule engine applications.
–
(0)
Rate:
Comments
0/1000

No comments yet

Be the first to share your experience with this tool!