construct
A powerful declarative symmetric parser/builder for binary data
Decision gist · record as of 2026-08-14
Yes. Construct is stable, permissive-licensed, dependency-free, and well-suited for any project involving binary data parsing or building. The aging maintenance status (last release 989 days ago) is a minor concern but not a blocker—the API is mature and the repository remains active. Install it if you need declarative binary format handling.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Low friction: pure Python wheel with no runtime dependencies.
- Maintenance is aging—last release was 989 days ago—but the repository remains active with recent commits and the package is marked Production/Stable.
License · maintenance · safety
MIT (permissive) — MIT license is permissive; you can use this in commercial and proprietary projects with minimal restrictions, provided you include the license notice.
last release 2023-11-29 (989 days) · last repo commit 2025-04-22 · 1,013 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 7,211,974 downloads/mo, #1,768 on PyPI
Alternatives
Verify before relying
from construct import Struct, Int8ub, Array, Const, Byte, this
format = Struct(
"signature" / Const(b"BMP"),
"width" / Int8ub,
"height" / Int8ub,
"pixels" / Array(this.width * this.height, Byte),
)
data = format.build(dict(width=3, height=2, pixels=[7,8,9,11,12,13]))
parsed = format.parse(data)- Whether the 989-day gap since last release signals maintenance concerns or reflects API stability.
- Performance characteristics for large or deeply nested binary structures.
What it is and what it does
Construct is a library for defining binary data formats declaratively. Instead of writing imperative parsing code, you describe your data structure once—specifying fields, their types, sizes, and relationships—and Construct uses that definition in both directions: to parse binary data into Python objects and to build those objects back into binary. The library supports atomic constructs (integers, bytes, strings) and composite ones (structs, sequences, arrays, bitwise fields), plus advanced features like conditional branching, lazy parsing, pointers, and compression tunneling.
It's designed for developers who work with binary protocols, file formats, or network packets and want to avoid hand-rolling parse/build logic. The symmetry means your format definition is the single source of truth, reducing bugs and maintenance burden. Construct supports Python 3.6 through 3.11 and has no runtime dependencies, making it lightweight to add to any project.
Use it for
- Parse and build custom binary file formats (e.g., image headers, game assets, firmware blobs).
- Define and handle network protocol structures with bit-level field control.
- Reverse-engineer binary data formats by declaratively specifying their layout.
- Build serialization layers for embedded systems or low-level communication.
- Test binary parsers by round-tripping data through parse and build operations.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Construct is stable, permissive-licensed, dependency-free, and well-suited for any project involving binary data parsing or building. The aging maintenance status (last release 989 days ago) is a minor concern but not a blocker—the API is mature and the repository remains active. Install it if you need declarative binary format handling.
Install
construct on PyPI
Before you install
Low friction: pure Python wheel with no runtime dependencies. Maintenance is aging—last release was 989 days ago—but the repository remains active with recent commits and the package is marked Production/Stable.
License in practice
MIT license is permissive; you can use this in commercial and proprietary projects with minimal restrictions, provided you include the license notice.
Quickstart
from construct import Struct, Int8ub, Array, Const, Byte, this
format = Struct(
"signature" / Const(b"BMP"),
"width" / Int8ub,
"height" / Int8ub,
"pixels" / Array(this.width * this.height, Byte),
)
data = format.build(dict(width=3, height=2, pixels=[7,8,9,11,12,13]))
parsed = format.parse(data)Verify before relying
- Whether the 989-day gap since last release signals maintenance concerns or reflects API stability.
- Performance characteristics for large or deeply nested binary structures.
Package facts
| License | MIT permissive |
| Python support | Supports the current Python release >=3.6 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | None |
| Maintenance | Aging 989 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 7,211,974 / month, #1,768 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 :: DevelopersLicense :: OSI Approved :: MIT LicenseProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.6Programming Language :: Python :: 3.7Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPyTopic :: Software Development :: Build ToolsTopic :: Software Development :: Code GeneratorsTopic :: Software Development :: Libraries :: Python Modules |
Evidence: construct-2.10.70-py3-none-any.whl
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