Blackfriday is a Markdown processor implemented in Go. It is paranoid about its input (so you can safely feed it user-supplied data), it is fast, it supports common extensions (tables, smart punctuation substitutions, etc.), and it is safe for all utf-8 (unicode) input. HTML output is currently supported, along with Smartypants extensions. It started as a translation from C of Sundown. Blackfriday itself does nothing to protect against malicious content. If you are dealing with user-supplied markdown, we recommend running Blackfriday's output through HTML sanitizer such as Bluemonday. Blackfriday includes an algorithm for creating sanitized anchor names corresponding to a given input text. This algorithm is used to create anchors for headings when EXTENSION_AUTO_HEADER_IDS is enabled. The algorithm has a specification, so that other packages can create compatible anchor names and links to those anchors.