---
id: zodbpickle
version: "4.4"
license: ZPL-2.1
license_treatment: unclear
maintenance: active
---

# zodbpickle — Fork of Python 3 pickle module

License: unclear · Maintenance: active · Downloads: 220.2K/mo

## What it is and what it does

zodbpickle is a fork of Python's pickle module designed to bridge serialization between Python 2 and 3 codebases, particularly for ZODB (Zope Object Database) applications. It adds support for protocol 3 opcodes under Python 2 and restores the noload() operation removed in Python 3, which ZODB uses to retrieve persistent references without loading objects into memory.

The package handles the tricky cross-version problem where Python 2 strings and Python 3 bytes have different semantics: it provides encoding options (like errors='bytes') to let you control whether legacy pickles deserialize as bytes or strings. It also offers a choice between fast C-based and slow pure-Python implementations, useful for debugging or when C extensions aren't available. No runtime dependencies means it integrates cleanly into existing projects.

Use it for:

- Migrating ZODB databases from Python 2 to Python 3 while preserving pickled object compatibility
- Loading legacy Python 2 pickles in Python 3 applications with correct string/bytes handling
- Optimizing ZODB cache behavior by using noload() to inspect persistent references without object instantiation
- Comparing pickle behavior between C and pure-Python implementations during debugging
- Building cross-version serialization layers where standard pickle doesn't handle protocol 3 or legacy opcodes

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Provides a ZODB-compatible pickle interface that handles cross-version serialization between Python 2 and 3, with support for protocol 3 opcodes and the noload() operation.

Yes, if you work with ZODB or need to deserialize Python 2 pickles in Python 3. The package is actively maintained, has no security vulnerabilities, and solves a real compatibility problem. Install friction is moderate due to C compilation, but wheels are available for common platforms. Verify ZPL-2.1 license compatibility with your project first.

## Install

pip install zodbpickle
uv add zodbpickle
poetry add zodbpickle

## Installing zodbpickle

Before you install: Medium install friction due to compiled C extensions across multiple platforms (macOS x86/ARM, Linux i686/aarch64/x86_64, Windows). Active maintenance with recent release (102 days ago) and support for current Python versions including 3.14.

License in practice: Licensed under ZPL-2.1 (Zope Public License 2.1), but license treatment is marked unclear in the fact sheet—verify compatibility with your project's licensing requirements before use.

Quickstart:

from zodbpickle import pickle

# Load Python 2 pickle on Python 3
data = pickle.loads(b"S'\\xff'\np0\n.", encoding='bytes')

# Or use explicit implementation choice
from zodbpickle import fastpickle  # always C
from zodbpickle import slowpickle  # always Python

Requires Python 3.10 or later; compiled C extensions must build for your platform. Pickle module security warning: never unpickle untrusted data.

Verify before relying:

- Exact scope of ZPL-2.1 license compatibility with common project licenses
- Performance characteristics of fastpickle vs slowpickle for typical workloads
- Whether noload() operation is actively used by ZODB or legacy-only

## Package facts

- License: ZPL-2.1 (unclear)
- Python support: supports_current
- Install friction: medium
- Maintenance: active
- Downloads: 220.2K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

zodb pickle compatibility, python 2 3 pickle bridge, cross-version serialization, pickle protocol 3 support, noload pickle operation, binary pickle handling, zodb persistent references, zodb, serialization, cross-version

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