RFCRestyle is a free browser add-on developed by Fred Gandt that aims to control the aesthetics and improve the navigability of HTML IETF RFC documents. It offers optional automatic redirects from plain text RFCs to their HTML versions.

When viewing ietf.org and rfc-editor.org pages, RFCRestyle will restyle HTML RFCs according to the user's preferences. It also creates a Table of Contents (ToC) with links to all page sections, which is accessible by click, tap, or the accesskey "T". Additionally, the add-on adds a color-coded legend to HTML RFC pages to enhance accessibility, with an accesskey of "L".

The restyling features of RFCRestyle include hiding white space and page separators when printing documents, as well as an adjustable fuzzy border around the text content to reduce tunnel vision when reading long documents.

RFCRestyle provides an options pop-up accessed by clicking the extension icon. Users can customize up to 5 profiles with unique settings, and changes to one profile will not affect the others. The add-on also offers the option to sync settings across all instances of Chrome if the user has Chrome's sync enabled.

Accessibility is a priority for RFCRestyle, with keyboard and mouse access well-tested. The add-on also supports accesskey access for the ToC and Legend, following web standards. However, touch screen access has not been extensively tested.

Privacy is ensured as RFCRestyle does not collect or process personal data, and its activity is not communicated with external applications. Settings are stored locally or optionally synced with other devices using Chrome's sync feature.

Overall, RFCRestyle is a useful browser add-on for those who frequently access HTML IETF RFC documents, offering restyling options and enhanced navigability.