Introduction

datalogic-rs is a JSONLogic rules engine: one Rust core with official bindings for Rust, Node.js, the browser (WASM), Python, Go, Java, .NET, and PHP, plus a React visual debugger. Rules are plain JSON; the same rule evaluates with identical semantics in every runtime, verified by a 1,565-case conformance battery that runs against the same core every binding ships.

This site is the reference documentation. For the project pitch, benchmarks, and package matrix, see the GitHub repository; to try rules in your browser right now, open the playground.

What is JSONLogic?

JSONLogic is a standard for expressing logic rules as JSON. This makes it:

• Portable: Rules can be stored in databases, sent over APIs, or embedded in configuration
• Language-agnostic: The same rules work across different implementations
• Human-readable: Rules are easier to understand than arbitrary code
• Safe: Rules can be evaluated without arbitrary code execution

A JSONLogic rule is a JSON object where the key is the operator name and the value is an array of arguments:

{"operator": [arg1, arg2, ...]}

For example:

{"and": [
  {">": [{"var": "age"}, 18]},
  {"==": [{"var": "country"}, "US"]}
]}

This rule checks if age > 18 AND country == "US".

How the engine works

datalogic-rs uses a two-phase approach:

1. Compilation: Your JSON logic is parsed and compiled into a reusable Logic. This phase:

   • Assigns OpCodes to built-in operators for fast dispatch
   • Pre-evaluates constant expressions
   • Analyzes structure for templating mode

2. Evaluation: The compiled logic is evaluated against your data with:

   • Direct OpCode dispatch (no string lookups at runtime)
   • Arena-allocated results that can borrow zero-copy from the input
   • A context stack for nested operations (map, filter, reduce)

Compile once, evaluate many: that is the pattern every binding exposes, and the reason evaluation runs in nanoseconds.

Find your language

Every language has a first-class chapter with install, quickstart, and the API surface:

How these docs are organized

• Getting Started — install, first evaluation, core concepts, starter microservice templates
• Operators — reference for all 59 built-in operators, with runnable examples on every page
• Languages — one chapter per binding (see the table above)
• Guides — custom operators, configuration, structured objects / templating, thread safety, and security & sandboxing
• Reference — use-case cookbook, performance, comparisons, migration, FAQ, and troubleshooting

Next steps

• Installation — add datalogic to your project
• Quick Start — first evaluation in minutes
• Use Cases & Examples — feature flags, pricing, validation, fraud scoring
• Coming from json-logic-js? — your rules run unchanged
• Migrating from v4