Testpage for OpenType Features

On this page I use my webfont Otfeat. It’s an icon font designed for testing OpenType features. For example:

smcp OFF OFF – The box is empty. That’s the initial situation and shows: The feature (here: smcp, small capitals) is either turned off or your browser isn’t able to display this feature.

smcp ON ON – After activation the box becomes filled. The feature smcp (small capitals) is turned on and your browser is able to show it.

[In meinem Blog gibt’s einen kurzen Überblick zu Otfeat auch in Deutsch.]
↓ More about OpenType features.

1) OpenType features switched on

Here you can see which OpenType features are supported by your browser. They are switched on by CSS (the two boxes with an X are not yet associated with a feature):


Here’s an image how it should look like (colored green for better destinction between the real test and the screenshot):

The letters of Otfeat with activated OpenType features

2) All features deactivated

The same text as above but this time the OpenType features are turned off:


If it doesn’t look like the following image your browser ignores the deactivation of OpenType features:

The letters of Otfeat without OpenType features

3) No features explicitly de-/activated

That’s the default status in your browser:


In some browsers individual OpenType features are activated by default, so some boxes may be filled (e. g. standard ligatures and kerning in Firefox).

Some details

This page was published on June 12th, 2012.

With the CSS-setting text-rendering: optimizeLegibility it is possible, to activate some OpenType features in Safari (e. g. liga or calt). But after some testing I decided not to use this setting. Firstly it caused some rendering problems in Google’s Chrome (especially at test Nº 3) and secondly once activated the features couldn’t be deactivated again (test Nº 2).

The feature locl (localized forms) is programmed with a default language. So this is no test if browsers are capable of using a special localized alternative depending on the corresponding language tag. Maybe I’ll implement this in a future version.

The kernig of Otfeat (more precisely between A and B) is applyed by individual kerning pairs. Kernig by a matrix of kerning classes is not tested and could be failing. Again something for a future version of Otfeat.

Even if fina seems to be working, it does not necessarely do what it should. This feature is meant to replace letters only when they are at the end of a word. In the following example the fina box should be filled only in the third case:


Otfeat’s small letters a–z represent single OpenType features which could be tested in any order. The capital letters are engaged with ligatures and context-sensitive features. The easiest thing that they will be shown correctly is to type the alphabet. At least the following pairs must be intact: AB, CD, EF, GH, IJ, RST and UVW. The pair KL has to be followed by an M. M and N depend on each other (in this order) and the O needs to follow an N.


Otfeat and this testpage was designed by Gerhard Großmann. You can reach me by mail to postfach2b [ät] web.de. I’m also on Twitter (@charakterziffer) and have a little blog in German.

Otfeat is released under CC-BY-NC-SA, so you can use and modify it for your own needs. Download: woff or ttf.


More about OpenType features

OpenType features are special functions which are programmed into a font. Examples are small capitals, swash letters or old-style figures. These functions can be activated in superior office and design programms – and as of late also in browsers.

The Microsoft website offers a detailed list with common OpenType features. There you also find descriptions for the 4-letter-abbreviations used in Otfeat. At I Love Typography there’s a nice article with concrete examples how some substitution features look like in practice. Typotheque published a tutorial for OpenType features in CSS.

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