Free online OTC to WOFF2 converter

Web projects need WOFF2 because browsers serve it efficiently, while an OTC file packages several OpenType fonts for desktop distribution. Converting the collection requires selecting one face first; a single WOFF2 file cannot represent the entire collection as one font.

What the OTC format is

OTC means OpenType Collection, a container holding multiple OpenType font faces that share tables such as glyph data, outlines, or metrics. It uses the .otc extension and is commonly encountered in operating-system font packages, multilingual type families, and fonts exported by professional font-development tools such as FontForge, Glyphs, and fontTools-based build systems.

An OTC can contain several styles, weights, scripts, or regional variants. The collection itself is not a single selectable typeface, so conversion must identify a face by its index, such as face 0 or face 3.

What the WOFF2 format is

WOFF2 is a compressed webfont container intended for CSS @font-face delivery. It normally contains one TrueType-flavored or CFF2 OpenType face and uses Brotli compression, often producing a substantially smaller file than the corresponding TTF or OTF.

WOFF2 reduces web transfer size and is supported by current Chromium, Firefox, Safari, and Edge releases. It is not normally used as an editable source or installed as a desktop font; retain the original OTC or an extracted OTF/TTF for editing and archival purposes.

How to actually convert OTC to WOFF2

For a no-install conversion, use the free converter on 101convert.com. Upload the .otc file, select the required collection member if the converter provides a face-selection option, choose WOFF2 as the output, and download the resulting file. If the service exposes no member selector, use fontTools locally so the correct face can be chosen explicitly.

With fontTools, install the WOFF2 dependencies:

python -m pip install "fonttools[woff]" brotli

List the faces in the collection:

python - <<'PY'
from fontTools.ttLib import TTCollection
import sys

collection = TTCollection(sys.argv[1])
for number, font in enumerate(collection.fonts):
    names = font['name'].names
    family = next((n.toUnicode() for n in names if n.nameID == 1), '?')
    style = next((n.toUnicode() for n in names if n.nameID == 2), '?')
    print(number, family, style)
PY
font.otc

Extract the required face and save it as WOFF2. Replace 0 with the index printed above:

python - <<'PY'
from fontTools.ttLib import TTCollection

collection = TTCollection("font.otc")
font = collection.fonts[0]
font.flavor = "woff2"
font.save("font-face.woff2")
PY

You can also subset during conversion, which removes unused glyphs and further reduces the file:

pyftsubset font.otc --font-number=0 --output-file=font-face.woff2 --flavor=woff2 --text="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"

Use a Unicode-range file or a broader character set instead of the example --text value when the web page needs accented characters, punctuation, non-Latin scripts, or symbols.

Quality, compatibility, and limitations

Conversion preserves the selected face's OpenType layout data when fontTools can encode its tables, but it does not merge all OTC members into one WOFF2. Convert each required member separately and give each output a distinct filename.

For browser use, declare the output with the matching family and style values, for example:

@font-face {
  font-family: "Example";
  src: url("font-face.woff2") format("woff2");
  font-weight: 400;
  font-style: normal;
}

Check the generated file in the target browsers and test shaping for the scripts it supports. Subsetting can remove required glyphs or OpenType features if its character set is too narrow. Font licensing also applies: a license that permits desktop distribution or modification may not permit web embedding, and WOFF2 does not change those terms.