Needle
What it is
Needle is a free, open-source Python testing library for developers checking website visuals and layout. It captures selected page regions and compares them with saved baseline screenshots, helping identify rendering changes. Tests can inspect rendered CSS, fonts, images, SVGs, calculated CSS values, and HTML element positions. Needle works with Selenium and nose, and documentation describes installing it with pip after Selenium. Browser-driver options include remote, Firefox, PhantomJS, Chrome, Internet Explorer, Opera, and Safari, with NeedleFirefox as the default. PIL is the default screenshot engine; PerceptualDiff and ImageMagick are alternatives that can produce a diff PNG when comparisons fail. Viewport dimensions can be set for responsive-site checks. Screenshots remain after successful tests by default, while cleanup is optional; failed comparison images remain available. Needle is listed for Linux, carries a BSD license, and PyPI lists version 0.5.0, released April 2, 2017. The plan is free.
For and against
For
- Baseline screenshot comparisons detect visual regressions
- Checks CSS values and element positions
- Works with Selenium and nose
- Multiple browser drivers are documented
- PerceptualDiff and ImageMagick can create diff PNGs
Against
- Latest listed release dates to April 2, 2017
- Screenshot cleanup is disabled by default
- Linux is the listed platform
- No SECURITY.md policy or published advisories
The verdict
Needle provides a focused visual-testing workflow with baseline comparisons, CSS checks, and browser automation. Its older listed release and Linux listing are important context for adoption.
Who it suits
Needle suits developers building Python-based visual and layout tests on Linux. It is useful when Selenium, nose, browser-driver choices, baseline screenshots, and responsive viewport checks fit the workflow.
Plans and prices
Needle
Open-source Python package · BSD license
Read 10 Oct 2026 · github.com
On the record
- Additional checks
- It also provides tools for testing calculated CSS values and HTML element positions.github.com · read 5 Oct 2026
- Baseline workflow
- Tests can save an initial screenshot as a baseline and compare later captures against it to detect regressions.needle.readthedocs.io · read 10 Oct 2026
- Browser automation
- Needle works with Selenium and nose.needle.readthedocs.io · read 10 Oct 2026
- Browser drivers
- The documentation lists NeedleRemote, NeedlePhantomJS, NeedleFirefox, NeedleChrome, NeedleIe, NeedleOpera, and NeedleSafari drivers.needle.readthedocs.io · read 5 Oct 2026
- Cleanup
- Screenshot cleanup after successful tests is optional and disabled by default.needle.readthedocs.io · read 5 Oct 2026
- Cleanup behavior
- Screenshot files are kept by default after successful tests, with an option to delete them; screenshots from failing comparisons remain available for inspection.needle.readthedocs.io · read 10 Oct 2026
- Comparison engines
- The documented screenshot engines are PIL, PerceptualDiff, and ImageMagick; PerceptualDiff and ImageMagick can produce diff images when tests fail.needle.readthedocs.io · read 10 Oct 2026
- Default driver
- The documentation says Needle uses NeedleFirefox by default.needle.readthedocs.io · read 5 Oct 2026
- Difference output
- The documentation says PerceptualDiff and ImageMagick generate a diff PNG when a test fails.needle.readthedocs.io · read 5 Oct 2026
- Image engines
- The default screenshot engine is PIL, with PerceptualDiff and ImageMagick also available.needle.readthedocs.io · read 5 Oct 2026
- Installation
- The documentation installs Needle with pip and lists Selenium as a dependency to install.needle.readthedocs.io · read 10 Oct 2026
- Integrations
- The README demonstrates a nose test case using Selenium to open a web page and check an element screenshot.github.com · read 10 Oct 2026
- Intended users
- The package metadata classifies Needle for developers and as a Python testing library.github.com · read 5 Oct 2026
- License
- The package metadata classifies Needle under the OSI-approved BSD License.github.com · read 10 Oct 2026
- Purpose
- Needle tests CSS and other web visuals by comparing screenshots with known good screenshots.github.com · read 10 Oct 2026
- Release
- PyPI lists version 0.5.0, released April 2, 2017, as the latest release.pypi.org · read 5 Oct 2026
- Security
- GitHub reports that the project has no SECURITY.md policy and no published security advisories.github.com · read 5 Oct 2026
- Supported environments
- Package metadata describes Needle as operating-system independent and intended for developers.github.com · read 10 Oct 2026
