colander
A simple schema-based serialization and deserialization library
Decision gist · record as of 2026-08-14
Yes. Colander is a mature, actively maintained library with low install friction, no known vulnerabilities, and a permissive license. It solves a common problem—validating and serializing structured data—with a clean, extensible API. Install it if you need schema-based validation and serialization in a web framework or data-processing pipeline.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Low install friction with only two runtime dependencies (translationstring and iso8601).
- The package is actively maintained with recent commits and supports Python 3.7, 3.8, 3.9, 3.10, 3.11, and PyPy 3.8.
License · maintenance · safety
permissive license (permissive) — Licensed under a BSD-derived permissive license (Repoze Public License), which permits commercial and private use with minimal restrictions.
last release 2023-01-03 (1319 days) · last repo commit 2026-08-02 · 462 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 240,223 downloads/mo, #8,907 on PyPI
Alternatives
Verify before relying
pip install colander
import colander
class PersonSchema(colander.MappingSchema):
name = colander.SchemaNode(colander.String())
age = colander.SchemaNode(colander.Integer())
schema = PersonSchema()
data = schema.deserialize({'name': 'Alice', 'age': 'value'})
print(schema.serialize(data))- Whether the package's locale data and internationalization support covers all languages relevant to your use case.
- Performance characteristics when validating deeply nested or very large data structures.
What it is and what it does
Colander is a schema-based serialization and deserialization library that converts between Python data structures and flat representations (strings, mappings, lists). It lets you define schemas declaratively—specifying types, validators, and transformations—then use them to validate incoming data and convert outgoing data to a serializable form.
The package is designed for web frameworks and APIs where you need to validate user input (form data, JSON payloads) and ensure it matches an expected structure before processing. It handles type coercion, custom validation logic, nested structures, and error reporting. With only two runtime dependencies and support for Python 3.7 and later, it integrates easily into most projects.
Use it for
- Validate and deserialize JSON or form data in web applications before passing it to business logic.
- Define and enforce data schemas for REST API request and response bodies.
- Serialize Python objects to JSON-safe dictionaries for API responses or storage.
- Build custom validators for domain-specific constraints (email, URL, date ranges, enums).
- Coerce and normalize user input (strings to integers, dates, etc.) with clear error messages.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Colander is a mature, actively maintained library with low install friction, no known vulnerabilities, and a permissive license. It solves a common problem—validating and serializing structured data—with a clean, extensible API. Install it if you need schema-based validation and serialization in a web framework or data-processing pipeline.
Install
colander on PyPI
Before you install
Low install friction with only two runtime dependencies (translationstring and iso8601). The package is actively maintained with recent commits and supports Python 3.7, 3.8, 3.9, 3.10, 3.11, and PyPy 3.8.
License in practice
Licensed under a BSD-derived permissive license (Repoze Public License), which permits commercial and private use with minimal restrictions.
Quickstart
pip install colander
import colander
class PersonSchema(colander.MappingSchema):
name = colander.SchemaNode(colander.String())
age = colander.SchemaNode(colander.Integer())
schema = PersonSchema()
data = schema.deserialize({'name': 'Alice', 'age': 'value'})
print(schema.serialize(data))Verify before relying
- Whether the package's locale data and internationalization support covers all languages relevant to your use case.
- Performance characteristics when validating deeply nested or very large data structures.
Package facts
| License | permissive license permissive |
| Python support | Supports the current Python release >=3.7 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 2 packagestranslationstringiso8601 |
| Maintenance | Actively maintained 1,319 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 240,223 / month, #8,907 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 6 - MatureIntended Audience :: DevelopersLicense :: Repoze Public LicenseOperating System :: OS IndependentProgramming Language :: PythonProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.7Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPy |
Evidence: colander-2.0-py3-none-any.whl
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See also apischema · azure-schemaregistry-avroserializer · peppercorn · yamale · fastjsonschema · docspec · databind · paradict · xmlschema · jsons