Needle
Needle is an open-source Python testing library for developers checking how websites render.
What Needle is
Needle is an open-source Python testing library for developers checking how websites render. It captures selected page areas and compares them with saved baseline screenshots to detect visual changes. It can also check calculated CSS values and HTML element positions, and its visual checks cover rendered CSS, fonts, images, and SVGs. Needle is designed to work with Selenium and nose; the documentation describes installing it with pip after Selenium. Listed WebDriver options include remote, Firefox, PhantomJS, Chrome, IE, Opera, and Safari, with NeedleFirefox as the default. PIL is the default screenshot engine, while PerceptualDiff and ImageMagick are alternatives that can create a diff PNG when a comparison fails. Tests can set viewport dimensions, including for responsive-site checks. Screenshots remain after successful tests by default, though cleanup can be enabled; failed-comparison screenshots remain available for inspection. Package metadata describes Needle as operating-system independent, while the listed platform is Linux. Its repository includes a BSD license, and PyPI lists version 0.5.0 as the latest release, released April 2, 2017.
Good
- Compares page captures with baseline screenshots
- Checks CSS values and element positions
- Offers multiple browser drivers
- Supports viewport dimensions for responsive checks
- Diff PNGs are available with two engines
Watch out
- Latest listed release dates to April 2, 2017
- Screenshot cleanup after passing tests is off by default
- No SECURITY.md policy or published security advisories are listed
Who it suits
Needle suits developers writing Python tests for visual website changes, CSS values, or element positions. It may be useful when Selenium and nose are part of the testing setup.
Verdict
Needle combines screenshot comparison with checks for CSS values and element positions. Its listed browser drivers and comparison engines offer options for developer testing, though its latest listed release is from 2017.
Plans and prices
From Needle's own pricing page, checked 10 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Needle | Free | Open-source Python package · BSD license |
The facts
Each one read from Needle's own pages, with the date it was checked.
What it does
- Additional checks
- It also provides tools for testing calculated CSS values and HTML element positions.checked 5 Oct 2026
- Baseline workflow
- Tests can save an initial screenshot as a baseline and compare later captures against it to detect regressions.checked 10 Oct 2026
- Cleanup
- Screenshot cleanup after successful tests is optional and disabled by default.checked 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.checked 10 Oct 2026
- Comparison engines
- The documented screenshot engines are PIL, PerceptualDiff, and ImageMagick; PerceptualDiff and ImageMagick can produce diff images when tests fail.checked 10 Oct 2026
- Default driver
- The documentation says Needle uses NeedleFirefox by default.checked 5 Oct 2026
- Difference output
- The documentation says PerceptualDiff and ImageMagick generate a diff PNG when a test fails.checked 5 Oct 2026
- Image engines
- The default screenshot engine is PIL, with PerceptualDiff and ImageMagick also available.checked 5 Oct 2026
- Installation
- The documentation installs Needle with pip and lists Selenium as a dependency to install.checked 10 Oct 2026
- Integrations
- The README demonstrates a nose test case using Selenium to open a web page and check an element screenshot.checked 10 Oct 2026
- Intended users
- The package metadata classifies Needle for developers and as a Python testing library.checked 5 Oct 2026
- License
- The package metadata classifies Needle under the OSI-approved BSD License.checked 10 Oct 2026
- Purpose
- Needle tests CSS and other web visuals by comparing screenshots with known good screenshots.checked 10 Oct 2026
- Release
- PyPI lists version 0.5.0, released April 2, 2017, as the latest release.checked 5 Oct 2026
- Security
- GitHub reports that the project has no SECURITY.md policy and no published security advisories.checked 5 Oct 2026
- Supported environments
- Package metadata describes Needle as operating-system independent and intended for developers.checked 10 Oct 2026
- Viewport
- Tests can set browser viewport dimensions, which the documentation describes as useful for responsive-site testing.checked 5 Oct 2026
- Viewport testing
- Needle lets tests set browser viewport dimensions, including for responsive site testing.checked 10 Oct 2026
- Visual checks
- It can test rendered CSS, fonts, images, SVGs, calculated CSS values, and HTML element positions.checked 10 Oct 2026
- WebDrivers
- The documentation lists Firefox, remote, PhantomJS, Chrome, IE, Opera, and Safari WebDriver options.checked 10 Oct 2026
Where it runs
- Browser automation
- Needle works with Selenium and nose.checked 10 Oct 2026
- Browser drivers
- The documentation lists NeedleRemote, NeedlePhantomJS, NeedleFirefox, NeedleChrome, NeedleIe, NeedleOpera, and NeedleSafari drivers.checked 5 Oct 2026
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