freezegun
Let your Python tests travel through time
Decision gist · record as of 2026-08-14
Yes. FreezeGun is a mature, widely-used testing utility with no known vulnerabilities, permissive licensing, and low install friction. It solves a real problem—making time-dependent tests deterministic—and is the de facto standard for this in Python. The aging maintenance status reflects stability rather than abandonment; the last commit was recent and the repository is active.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Low friction: pure Python wheel with a single runtime dependency (python-dateutil).
- Last release was recent (2025-08-09), though the project shows aging maintenance status with no release for 370 days prior.
License · maintenance · safety
Apache-2.0 (permissive) — Apache-2.0 is permissive; you can use, modify, and distribute this package freely in commercial and private projects with minimal restrictions.
last release 2025-08-09 (370 days) · last repo commit 2025-08-19 · 4,522 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 60,817,178 downloads/mo, #500 on PyPI
Alternatives
Verify before relying
pip install freezegun
from freezegun import freeze_time
import datetime
@freeze_time("2012-01-14")
def test_frozen():
assert datetime.datetime.now() == datetime.datetime(2012, 1, 14)- Whether the 370-day gap before the latest release indicates ongoing maintenance or a stable, feature-complete state
What it is and what it does
FreezeGun intercepts calls to datetime.datetime.now(), datetime.date.today(), time.time(), time.monotonic(), and related time functions, returning a fixed or controlled time instead. This lets you write deterministic tests for time-dependent code without waiting for real time to pass or dealing with flaky assertions based on system clock.
You apply it as a decorator on test functions or classes, wrap code in a context manager, or call start/stop manually. It supports timezone offsets, manual time advancement (tick), automatic time progression (auto_tick_seconds), and even generator-based time sequences. The library uses python-dateutil to parse human-readable date strings like "Jan 14th, 2012" in addition to ISO formats.
Use it for
- Test code that checks if a deadline has passed or a timeout has expired without actually waiting
- Verify behavior at specific dates (e.g., leap years, daylight saving transitions) deterministically
- Mock time.monotonic() and time.perf_counter() to test timing-sensitive logic in unit tests
- Simulate time progression within a test by using tick() or auto_tick_seconds to advance the frozen clock
- Test scheduled tasks or cron-like behavior by freezing time at known points and advancing it step-by-step
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
FreezeGun is a mature, widely-used testing utility with no known vulnerabilities, permissive licensing, and low install friction. It solves a real problem—making time-dependent tests deterministic—and is the de facto standard for this in Python. The aging maintenance status reflects stability rather than abandonment; the last commit was recent and the repository is active.
Install
freezegun on PyPI
Before you install
Low friction: pure Python wheel with a single runtime dependency (python-dateutil). Last release was recent (2025-08-09), though the project shows aging maintenance status with no release for 370 days prior.
License in practice
Apache-2.0 is permissive; you can use, modify, and distribute this package freely in commercial and private projects with minimal restrictions.
Quickstart
pip install freezegun
from freezegun import freeze_time
import datetime
@freeze_time("2012-01-14")
def test_frozen():
assert datetime.datetime.now() == datetime.datetime(2012, 1, 14)Verify before relying
- Whether the 370-day gap before the latest release indicates ongoing maintenance or a stable, feature-complete state
Package facts
| License | Apache-2.0 permissive |
| Python support | Supports the current Python release >=3.8 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 1 packagepython-dateutil |
| Maintenance | Aging 370 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 60,817,178 / month, #500 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Programming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPy |
Evidence: freezegun-1.5.5-py3-none-any.whl
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See also pytest-freezegun · time-machine · pytest-freezer · timeago · delorean · types-freezegun · fiscalyear · snaptime · ago · asyncmock