librt
Mypyc runtime library
Decision gist · record as of 2026-08-14
Yes, if you are using mypyc to compile Python code to C extensions. The library is actively maintained, has no external dependencies, and is designed to improve performance of compiled code. Not relevant for standard Python projects that do not use mypyc.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.9 or later.
- PyPy is not supported; use CPython for type checking if librt is needed as a mypy dependency.
- Medium install friction due to compiled wheels across many platforms.
License · maintenance · safety
MIT (permissive) — MIT license permits commercial and private use with minimal restrictions, making it suitable for most projects.
last release 2026-08-07 (7 days) · last repo commit 2026-08-07 · 14 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 146,820,956 downloads/mo, #272 on PyPI
Alternatives
Verify before relying
pip install librt
from librt.vecs import vec
from librt.strings import Builder
v = vec()- Performance improvement magnitude when using librt in mypyc-compiled code versus standard Python equivalents
- Whether librt can be used standalone or only as part of mypyc compilation workflow
- Practical performance gains from vec, Builder, and Base64 implementations in real-world mypyc usage
What it is and what it does
librt is a runtime library that provides C-based implementations of common data structures and operations for code compiled with the mypyc compiler. It offers growable packed arrays (vec), fast string and bytes builders, and SIMD-accelerated Base64 encoding/decoding. The library is designed to make mypyc-compiled extensions faster by replacing Python standard library equivalents with optimized C versions.
The package is synced from the mypy repository and is primarily used as a dependency for mypyc compilation workflows. It has no runtime dependencies and supports Python 3.9 through 3.14 across multiple platforms (macOS, Linux, Windows, including ARM and RISC-V architectures). PyPy is not supported. Development and issue tracking happen in the mypyc project.
Use it for
- Use vec type in mypyc-compiled code as a faster alternative to Python lists for performance-critical operations
- Build strings and bytes efficiently in compiled code using librt's Builder classes for large concatenation operations
- Encode or decode Base64 data with SIMD acceleration in mypyc-compiled functions
- Provide type-checked runtime support when compiling Python code to C extensions with mypyc
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you are using mypyc to compile Python code to C extensions.
The library is actively maintained, has no external dependencies, and is designed to improve performance of compiled code. Not relevant for standard Python projects that do not use mypyc.
Install
librt on PyPI
Before you install
Medium install friction due to compiled wheels across many platforms. Actively maintained with a release 7 days ago. No runtime dependencies simplifies deployment.
Requires Python 3.9 or later. PyPy is not supported; use CPython for type checking if librt is needed as a mypy dependency.
License in practice
MIT license permits commercial and private use with minimal restrictions, making it suitable for most projects.
Quickstart
pip install librt
from librt.vecs import vec
from librt.strings import Builder
v = vec()Verify before relying
- Performance improvement magnitude when using librt in mypyc-compiled code versus standard Python equivalents
- Whether librt can be used standalone or only as part of mypyc compilation workflow
- Practical performance gains from vec, Builder, and Base64 implementations in real-world mypyc usage
Package facts
| License | MIT permissive |
| Python support | Supports the current Python release >=3.9 |
| Install friction | Medium. Platform-specific wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 7 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 146,820,956 / month, #272 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 3 - AlphaEnvironment :: ConsoleIntended Audience :: DevelopersProgramming 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 :: 3.9Topic :: Software DevelopmentTyping :: Typed |
Evidence: librt-0.15.0-cp310-cp310-macosx_10_9_x86_64.whl; librt-0.15.0-cp310-cp310-macosx_11_0_arm64.whl; librt-0.15.0-cp310-cp310-manylinux2014_aarch64.manylinux_2_17_aarch64.manylinux_2_28_aarch64.whl; librt-0.15.0-cp310-cp310-manylinux2014_i686.manylinux_2_17_i686.manylinux_2_28_i686.whl; librt-0.15.0-cp310-cp310-manylinux2014_ppc64le.manylinux_2_17_ppc64le.manylinux_2_28_ppc64le.whl; librt-0.15.0-cp310-cp310-manylinux2014_x86_64.manylinux_2_17_x86_64.manylinux_2_28_x86_64.whl; librt-0.15.0-cp310-cp310-manylinux_2_34_riscv64.manylinux_2_39_riscv64.whl; librt-0.15.0-cp310-cp310-musllinux_1_2_aarch64.whl; librt-0.15.0-cp310-cp310-musllinux_1_2_i686.whl; librt-0.15.0-cp310-cp310-musllinux_1_2_ppc64le.whl; librt-0.15.0-cp310-cp310-musllinux_1_2_riscv64.whl; librt-0.15.0-cp310-cp310-musllinux_1_2_x86_64.whl; librt-0.15.0-cp310-cp310-win32.whl; librt-0.15.0-cp310-cp310-win_amd64.whl; librt-0.15.0-cp311-cp311-macosx_10_9_x86_64.whl; librt-0.15.0-cp311-cp311-macosx_11_0_arm64.whl; librt-0.15.0-cp311-cp311-manylinux2014_aarch64.manylinux_2_17_aarch64.manylinux_2_28_aarch64.whl; librt-0.15.0-cp311-cp311-manylinux2014_i686.manylinux_2_17_i686.manylinux_2_28_i686.whl; librt-0.15.0-cp311-cp311-manylinux2014_ppc64le.manylinux_2_17_ppc64le.manylinux_2_28_ppc64le.whl; librt-0.15.0-cp311-cp311-manylinux2014_x86_64.manylinux_2_17_x86_64.manylinux_2_28_x86_64.whl
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See also pybase64 · ast-serialize · sqlglotc · base64io · mypy-extensions · base2048 · pythran · numpy-minmax · faster-eth-abi · binapy