json-logic

What it is and what it does

json-logic is a Python implementation of the JsonLogic format, a language-agnostic way to express conditional logic as JSON. It lets you write rules once and execute them identically in Python, JavaScript, PHP, and other supported languages, making it useful for sharing validation or decision logic between client and server code or storing rules in a database alongside data.

The package provides a single main function, jsonLogic, which takes a rule object (and optionally a data object) and returns the result of evaluating that rule. Rules use a prefix notation where the operator is the key and operands are the value—for example, {"==": [1, 1]} evaluates to True. It supports comparison operators, logical operators (and, or, not), variable references (var), and nested rule composition. No external dependencies are required.

Use it for:

• Store validation or authorization rules in a database and execute them server-side without code deployment
• Share conditional business logic between a JavaScript front-end and Python back-end using the same JSON rule format
• Build a rules engine for A/B testing, feature flags, or dynamic pricing without writing conditional code
• Serialize complex decision trees as JSON for configuration files or API responses that clients can also interpret
• Implement user-defined filters or queries in a web application by accepting JsonLogic rules from the client

Worth the install?

AI-flagged interpretation of the facts on this page — verify before relying

Parses and executes JsonLogic rules—a JSON-serializable format for expressing conditional logic—allowing you to share the same rules across front-end and back-end code regardless of language.

Yes, if you need a lightweight, language-agnostic rules engine and can accept dormant maintenance. The package has no dependencies, installs easily, and works for straightforward JsonLogic evaluation. However, verify compatibility with your Python version (classifiers list only up to 3.4) and be aware that no active maintenance means no bug fixes or feature updates—suitable for stable, self-contained use cases but risky if you depend on ongoing support.

Install

json-logic on PyPI

pip install json-logic

uv add json-logic

poetry add json-logic

Installing json-logic

Before you install

Installation is straightforward with no runtime dependencies. The package is dormant (last release 2015-12-04, last commit 2023-12-19), so expect no active maintenance, though the repository remains unarchived.

License in practice

Licensed under MIT (permissive), so you can use, modify, and distribute this package freely in commercial and private projects with minimal restrictions.

Quickstart

pip install json-logic

from json_logic import jsonLogic

rules = {"==": [1, 1]}
result = jsonLogic(rules)
# True

rules = {"var": "name"}
data = {"name": "Alice"}
result = jsonLogic(rules, data)
# "Alice"

Verify before relying

• Whether the package works reliably with modern Python versions beyond those listed in classifiers (3.4 and earlier)
• Whether the dormant status and lack of recent releases pose compatibility risks with current ecosystems

Package facts

Evidence: json_logic-0.6.3-py2.py3-none-any.whl

Keywords: json-logic

Tags

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