rule-engine
A lightweight, optionally typed expression language with a custom grammar for matching arbitrary Python objects.
Decision gist · record as of 2026-08-14
Yes. Rule Engine is actively maintained, has no known vulnerabilities, low install friction, and solves a clear problem: declarative rule evaluation without writing Python code. The permissive BSD-3-Clause license poses no restrictions. Install if you need to evaluate user-defined or data-driven matching logic; skip if you're writing simple hardcoded conditionals.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.10 or later; Version 6.0 will drop Python 3.10 support.
- Low install friction with a single runtime dependency (python-dateutil).
- Active maintenance with a recent release 37 days ago and ongoing repository activity.
License · maintenance · safety
BSD-3-Clause (permissive) — BSD-3-Clause permissive license allows commercial and private use without restriction.
last release 2026-07-08 (37 days) · last repo commit 2026-08-02 · 593 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 448,253 downloads/mo, #6,604 on PyPI
Alternatives
Verify before relying
pip install rule-engine
import rule_engine
rule = rule_engine.Rule('first_name == "Luke" and email =~ ".*@rebels.org$"')
rule.matches({'first_name': 'Luke', 'email': 'luke@rebels.org'})- Performance characteristics when evaluating large rule sets or complex expressions against many objects
- Thread-safety guarantees beyond the documented claim in the description excerpt
What it is and what it does
Rule Engine is a domain-specific language (DSL) for writing matching rules as strings in Python code. You define rules using a custom grammar similar to Python syntax, then apply them to dictionaries or objects to test whether they match. The language supports optional type annotations to catch errors early, regular expression matching on strings, datetime values, and compound types like lists, dicts, and sets.
Typical usage involves creating a Rule object with an expression string, optionally providing a typed Context to validate symbol names and operations, then calling the rule's matching method on data objects. It's designed for scenarios where you need to express filtering or matching logic in a declarative, user-friendly way rather than writing Python conditionals directly. The package includes a debug REPL for experimentation.
Use it for
- Filter records in a database or API response based on user-defined rule expressions without writing custom Python code
- Implement a rules engine for workflow automation where business logic is expressed as strings and evaluated at runtime
- Validate incoming data against typed rule sets to ensure only objects matching specific criteria proceed
- Build a query language for applications where end users need to define matching criteria without Python knowledge
- Match log entries or events against rule expressions for alerting or log aggregation systems
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Rule Engine is actively maintained, has no known vulnerabilities, low install friction, and solves a clear problem: declarative rule evaluation without writing Python code. The permissive BSD-3-Clause license poses no restrictions. Install if you need to evaluate user-defined or data-driven matching logic; skip if you're writing simple hardcoded conditionals.
Install
rule-engine on PyPI
Before you install
Low install friction with a single runtime dependency (python-dateutil). Active maintenance with a recent release 37 days ago and ongoing repository activity.
Requires Python 3.10 or later; Version 6.0 will drop Python 3.10 support.
License in practice
BSD-3-Clause permissive license allows commercial and private use without restriction.
Quickstart
pip install rule-engine
import rule_engine
rule = rule_engine.Rule('first_name == "Luke" and email =~ ".*@rebels.org$"')
rule.matches({'first_name': 'Luke', 'email': 'luke@rebels.org'})Verify before relying
- Performance characteristics when evaluating large rule sets or complex expressions against many objects
- Thread-safety guarantees beyond the documented claim in the description excerpt
Package facts
| License | BSD-3-Clause permissive |
| Python support | Supports the current Python release >=3.10 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 1 packagepython-dateutil |
| Maintenance | Actively maintained 37 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 448,253 / month, #6,604 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableEnvironment :: ConsoleIntended Audience :: DevelopersOperating System :: OS IndependentProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Topic :: Software Development :: Libraries :: Python Modules |
Evidence: rule_engine-5.0.2-py3-none-any.whl
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