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(md/security)=
# Security
Many people don't understand that markdown format does not care much about security.
In many cases you have to pass output to sanitizers.
`markdown-it` provides 2 possible strategies to produce safe output:
1. Don't enable HTML. Extend markup features with [plugins](md/plugins).
We think it's the best choice and use it by default.
- That's ok for 99% of user needs.
- Output will be safe without sanitizer.
2. Enable HTML and use external sanitizer package(s).
Also by default `markdown-it` prohibits some kind of links, which could be used
for XSS:
- `javascript:`, `vbscript:`
- `file:`
- `data:`, except some images (gif/png/jpeg/webp).
So, by default `markdown-it` should be safe. We care about it.
If you find a security problem - contact us via tracker or email.
Such reports are fixed with top priority.
## Plugins
Usually, plugins operate with tokenized content, and that's enough to provide safe output.
But there is one non-evident case you should know - don't allow plugins to generate arbitrary element `id` and `name`.
If those depend on user input - always add prefixes to avoid DOM clobbering.
See [discussion](https://github.com/markdown-it/markdown-it/issues/28) for details.
So, if you decide to use plugins that add extended class syntax or autogenerating header anchors - be careful.
(md/performance)=
# Performance
You can view our continuous integration benchmarking analysis at: <https://executablebooks.github.io/markdown-it-py/dev/bench/>,
or you can run it for yourself within the repository:
```console
$ tox -e py38-bench-packages -- --benchmark-columns mean,stddev
Name (time in ms) Mean StdDev
---------------------------------------------------------------
test_mistune 70.3272 (1.0) 0.7978 (1.0)
test_mistletoe 116.0919 (1.65) 6.2870 (7.88)
test_markdown_it_py 152.9022 (2.17) 4.2988 (5.39)
test_commonmark_py 326.9506 (4.65) 15.8084 (19.81)
test_pymarkdown 368.2712 (5.24) 7.5906 (9.51)
test_pymarkdown_extra 640.4913 (9.11) 15.1769 (19.02)
test_panflute 678.3547 (9.65) 9.4622 (11.86)
---------------------------------------------------------------
```
As you can see, `markdown-it-py` doesn't pay with speed for it's flexibility.
```{note}
`mistune` is not CommonMark compliant, which is what allows for its
faster parsing, at the expense of issues, for example, with nested inline parsing.
See [mistletoes's explanation](https://github.com/miyuchina/mistletoe/blob/master/performance.md)
for further details.
```
|
