pyasn1
Pure-Python implementation of ASN.1 types and DER/BER/CER codecs (X.208)
Decision gist · record as of 2026-08-14
Yes. Pyasn1 is actively maintained, has no dependencies, carries a permissive BSD-2-Clause license, and ranks in the top 100 PyPI packages by downloads. Install it if you need to work with ASN.1-based protocols or formats; it is the standard library for this in Python and has no known vulnerabilities.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Installation is straightforward with no runtime dependencies and low friction.
- The package is actively maintained with recent commits, though repository activity is modest (52 stars).
License · maintenance · safety
BSD-2-Clause (permissive) — BSD-2-Clause is permissive and imposes minimal restrictions; you can use pyasn1 in commercial and proprietary projects with only attribution required.
last release 2026-07-09 (36 days) · last repo commit 2026-08-10 · 52 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 570,897,622 downloads/mo, #62 on PyPI
Alternatives
Verify before relying
pip install pyasn1
from pyasn1.type import univ, namedtype
from pyasn1.codec.der import encoder, decoder
class Record(univ.Sequence):
componentType = namedtype.NamedTypes(
namedtype.NamedType('id', univ.Integer())
)
record = Record()
record['id'] = 123
encoded = encoder.encode(record)
decoded, _ = decoder.decode(encoded, asn1Spec=Record())- Performance characteristics when handling large or deeply nested ASN.1 structures
- Whether the contributed Asn1ate compiler is actively maintained or available separately
- Applicability to specific protocols beyond SNMP mentioned in the description
What it is and what it does
Pyasn1 is a pure-Python implementation of ASN.1 types and codecs that lets you work with ASN.1 data structures as Python objects. It supports encoding and decoding via BER, CER, DER, and native Python codecs, making it suitable for any protocol or file format built on ASN.1 specification—historically SNMP, but generalized for a wide range of protocols.
You define ASN.1 structures as Python classes, instantiate them like regular objects, and serialize or deserialize them to binary form for transmission or storage. The package handles the complexity of ASN.1 tagging, optional fields, and defaults, while letting you treat the resulting objects much like Python dicts and lists. It has no runtime dependencies, works with Python 3.8 and later, and is thread-safe.
Use it for
- Encode and decode SNMP protocol messages for network management applications
- Serialize complex nested data structures for transmission over binary protocols
- Convert between ASN.1 wire format and native Python dicts for easier manipulation
- Build protocol implementations that rely on ASN.1 data serialization standards
- Work with file formats and protocols based on ASN.1 specification
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Pyasn1 is actively maintained, has no dependencies, carries a permissive BSD-2-Clause license, and ranks in the top 100 PyPI packages by downloads. Install it if you need to work with ASN.1-based protocols or formats; it is the standard library for this in Python and has no known vulnerabilities.
Install
pyasn1 on PyPI
Before you install
Installation is straightforward with no runtime dependencies and low friction. The package is actively maintained with recent commits, though repository activity is modest (52 stars).
License in practice
BSD-2-Clause is permissive and imposes minimal restrictions; you can use pyasn1 in commercial and proprietary projects with only attribution required.
Quickstart
pip install pyasn1
from pyasn1.type import univ, namedtype
from pyasn1.codec.der import encoder, decoder
class Record(univ.Sequence):
componentType = namedtype.NamedTypes(
namedtype.NamedType('id', univ.Integer())
)
record = Record()
record['id'] = 123
encoded = encoder.encode(record)
decoded, _ = decoder.decode(encoded, asn1Spec=Record())Verify before relying
- Performance characteristics when handling large or deeply nested ASN.1 structures
- Whether the contributed Asn1ate compiler is actively maintained or available separately
- Applicability to specific protocols beyond SNMP mentioned in the description
Package facts
| License | BSD-2-Clause permissive |
| Python support | Supports the current Python release >=3.8 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 36 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 570,897,622 / month, #62 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 :: DevelopersIntended Audience :: EducationIntended Audience :: Information TechnologyIntended Audience :: System AdministratorsIntended Audience :: Telecommunications IndustryNatural Language :: EnglishOperating System :: OS IndependentProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPyTopic :: CommunicationsTopic :: Software Development :: Libraries :: Python Modules |
Evidence: pyasn1-0.6.4-py3-none-any.whl
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See also asn1 · asn1crypto · asn1tools · pyasn1-modules · x690 · types-pyasn1 · pysmi · scalecodec · bech32m · bencode.py