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njsscan vs Pysa

njsscan

github.com

Pysa

pyre-check.org

Side by side

FigurenjsscanPysa
Price from—Free
Free plan—Yes
Free trial——
Open source——
Windows—Yes
macOSYesYes
LinuxYesYes
Self-hosted—Yes
Plans published01
Spec score · Static Application Security Testing Software5.6 (#23)8.3 (#6)

Plans

njsscan

No plans published.

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Pysa

  • Free (MIT-licensed open-source software)Free

Pysa pricing →

In their own words

njsscan

njsscan has no write-up on Specifiction yet; its figures are above.

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Pysa

Pysa is a free, open-source Python static analysis tool that uses taint analysis to identify potential security issues. It follows data from configured sources toward dangerous sinks, such as user-controlled request data reaching an eval call. Users configure sources, sinks, features and rules in taint.config, and annotate code with .pysa model files; built-in and common Python libraries have prewritten models and rules. Sanitizer models describe data that should lose taint, including function parameters and return values. Pysa analyzes the target repository and directories in the configured search_path, but not dependency source outside that scope. When it cannot access a function’s source, it assumes the return value retains taint, which can lead to false positives. Analysis may freeze on similarly sized projects if the machine lacks enough memory. The quickstart installs it with pip install pyre-check in a Python virtual environment. Pyre supports the Language Server Protocol, and a VSCode extension connects to a running server. SAPP can ingest results for viewing and filtering in a local web UI; a GitHub Action can run Pysa in CI and show findings in GitHub’s Security code scanning UI. Pysa requires Python 3.9 or later and relies on type information from Pyrefly. The project says it can analyze codebases with millions of lines. Its repository is MIT-licensed; the Pyre repository was archived on June 26, 2026, and says Pysa moved to its own repository.

Visit pyre-check.org