boltons
When they're not builtins, they're boltons.
Decision gist · record as of 2026-08-14
Yes. Boltons is a mature, actively maintained library with zero dependencies, a permissive license, and broad Python version support. It fills genuine gaps in the standard library with well-tested utilities. Install it when you need one or more of its utilities and want to avoid adding multiple specialized dependencies, or when you prefer to vendor individual modules into a project.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Low friction: pure Python, no runtime dependencies, and a wheel distribution.
- Active maintenance with a recent release 28 days ago and commits through August 2026.
License · maintenance · safety
permissive license (permissive) — BSD-licensed under a permissive license, allowing use in commercial and proprietary projects with minimal restrictions.
last release 2026-07-17 (28 days) · last repo commit 2026-08-07 · 6,914 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 26,164,252 downloads/mo, #888 on PyPI
Alternatives
Verify before relying
pip install boltons
from boltons.cacheutils import LRU
my_cache = LRU()
my_cache['key'] = 'value'- Whether all 230+ utilities are actively maintained or if some are deprecated
- Performance characteristics compared to specialized third-party alternatives for specific use cases
What it is and what it does
Boltons is a collection of pure-Python utilities that extend the standard library with commonly needed functionality. It includes data structures like OrderedMultiDict and LRU caches, file utilities for atomic writes, iteration helpers for chunking and windowing, recursive data structure operations, backoff/retry logic with jitter, and stack trace utilities. The library is designed as a middle ground—offering "good enough" implementations for basic use cases while acknowledging that specialized third-party libraries exist for advanced needs.
With no dependencies and a pure-Python implementation, boltons can be installed directly or individual modules can be vendored into projects. It is actively maintained, tested against Python 3.7 through 3.14 and PyPy3, and carries a permissive BSD license.
Use it for
- Implement an LRU cache for memoization or request caching without adding a dependency
- Perform atomic file writes to ensure data consistency in multi-process environments
- Iterate over sequences in chunks or sliding windows for batch processing or time-series analysis
- Recursively merge or iterate nested dictionaries and lists in configuration or data transformation tasks
- Add exponential backoff with jitter to retry logic for network requests or transient failures
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Boltons is a mature, actively maintained library with zero dependencies, a permissive license, and broad Python version support. It fills genuine gaps in the standard library with well-tested utilities. Install it when you need one or more of its utilities and want to avoid adding multiple specialized dependencies, or when you prefer to vendor individual modules into a project.
Install
boltons on PyPI
Before you install
Low friction: pure Python, no runtime dependencies, and a wheel distribution. Active maintenance with a recent release 28 days ago and commits through August 2026.
License in practice
BSD-licensed under a permissive license, allowing use in commercial and proprietary projects with minimal restrictions.
Quickstart
pip install boltons
from boltons.cacheutils import LRU
my_cache = LRU()
my_cache['key'] = 'value'Verify before relying
- Whether all 230+ utilities are actively maintained or if some are deprecated
- Performance characteristics compared to specialized third-party alternatives for specific use cases
Package facts
| License | permissive license permissive |
| Python support | Supports the current Python release >=3.7 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 28 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 26,164,252 / month, #888 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 :: BSD LicenseOperating System :: OS IndependentProgramming Language :: Python :: 3Programming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: 3.7Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPyTopic :: Software Development :: LibrariesTopic :: Utilities |
Evidence: boltons-26.1.0-py3-none-any.whl
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See also orderedmultidict · types-boltons · pylru · cachey · onecache · lru-dict · backports.functools-lru-cache · diskcache-weave · async-lru · methodtools