eventsourcing
Event sourcing in Python
Decision gist · record as of 2026-08-14
Yes. Eventsourcing is a mature, actively maintained library (stable since 2015, production-ready) with low install friction, no security vulnerabilities, and a permissive license. It's the right choice if you need event sourcing as a core pattern; if you're unsure whether event sourcing fits your problem, evaluate that architectural decision first before installing.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.10 or later; by default events are stored in memory using Python objects, but persistence modules can be configured via environment variables.
- Low friction: pure Python wheel with a single runtime dependency (typing_extensions).
- Actively maintained with a recent release 140 days ago and ongoing commits; repository shows 1681 stars and is not archived.
License · maintenance · safety
permissive license (permissive) — Permissive license allows commercial and private use without restriction; suitable for most projects without legal concern.
last release 2026-03-27 (140 days) · last repo commit 2026-07-27 · 1,681 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 91,476 downloads/mo, #13,515 on PyPI
Alternatives
Verify before relying
pip install eventsourcing
from eventsourcing.domain import Aggregate, event
from eventsourcing.application import Application
class Dog(Aggregate):
@event('Registered')
def __init__(self, name: str) -> None:
self.name = name
class DogSchool(Application):
def register_dog(self, name: str):
dog = Dog(name)
self.save(dog)
return dog.id
school = DogSchool()
dog_id = school.register_dog('Fido')- Performance characteristics under high-volume event streams or with large aggregates
- Scalability limits when using in-memory persistence versus external databases
- Compatibility of encryption/compression features with all supported database adapters
What it is and what it does
Eventsourcing provides a framework for building applications where every state change is recorded as an immutable event. Rather than storing current state directly, you define domain aggregates (like a Dog class) decorated with @event methods, then use an Application class to manage persistence and retrieval. The library handles event storage, replay, snapshotting, versioning, and optional encryption—supporting multiple backends (in-memory, SQLite, and external databases) configured through environment variables.
The core workflow is: define domain models with event decorators, create an application class that orchestrates saves and queries, then run your code against any configured persistence layer. Built-in features include optimistic concurrency control, compression, application-level encryption for PII compliance, and notification-based projections for CQRS patterns. It requires Python 3.10+ and depends only on typing_extensions.
Use it for
- Build audit-trail systems where every state change must be recorded and replayed for compliance or debugging
- Implement CQRS architectures with separate read and write models using notifications and projections
- Create domain-driven applications with strong consistency boundaries and event-based communication between aggregates
- Develop distributed systems where event logs serve as the source of truth for replication across nodes
- Encrypt sensitive domain events at the application level to meet GDPR or similar data protection requirements
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Eventsourcing is a mature, actively maintained library (stable since 2015, production-ready) with low install friction, no security vulnerabilities, and a permissive license. It's the right choice if you need event sourcing as a core pattern; if you're unsure whether event sourcing fits your problem, evaluate that architectural decision first before installing.
Install
eventsourcing on PyPI
Before you install
Low friction: pure Python wheel with a single runtime dependency (typing_extensions). Actively maintained with a recent release 140 days ago and ongoing commits; repository shows 1681 stars and is not archived.
Requires Python 3.10 or later; by default events are stored in memory using Python objects, but persistence modules can be configured via environment variables.
License in practice
Permissive license allows commercial and private use without restriction; suitable for most projects without legal concern.
Quickstart
pip install eventsourcing
from eventsourcing.domain import Aggregate, event
from eventsourcing.application import Application
class Dog(Aggregate):
@event('Registered')
def __init__(self, name: str) -> None:
self.name = name
class DogSchool(Application):
def register_dog(self, name: str):
dog = Dog(name)
self.save(dog)
return dog.id
school = DogSchool()
dog_id = school.register_dog('Fido')Verify before relying
- Performance characteristics under high-volume event streams or with large aggregates
- Scalability limits when using in-memory persistence versus external databases
- Compatibility of encryption/compression features with all supported database adapters
Package facts
| License | permissive license permissive |
| Python support | Supports the current Python release >=3.10.0 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 1 packagetyping_extensions |
| Maintenance | Actively maintained 140 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 91,476 / month, #13,515 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/StableIntended Audience :: DevelopersIntended Audience :: EducationIntended Audience :: Science/ResearchLicense :: OSI Approved :: BSD LicenseOperating System :: OS IndependentProgramming Language :: PythonProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Topic :: Software Development :: Libraries :: Python Modules |
Evidence: eventsourcing-9.5.4-py3-none-any.whl
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