Sample WOFF2 file (qa sans)

Handle it in code

Each snippet below was run against this exact file with Python 3.14.4 and Node 24.15.0 when this page was built, and the output shown is what it printed.

Python

Check the signature and the table directory before handing a font to a renderer. TrueType and OpenType list their tables in a plain directory; WOFF wraps the same tables with zlib; WOFF2 compresses them with Brotli, which the standard library cannot read.

import struct

REQUIRED = {"cmap", "head", "hhea", "hmtx", "maxp", "name", "post"}

with open("qa-sans.woff2", "rb") as f:
    data = f.read()
sig = data[:4]
if sig == b"wOF2":
    n = struct.unpack(">H", data[12:14])[0]
    print(f"WOFF2 with {n} tables, Brotli-compressed: read further with fontTools")
elif sig in (b"wOFF", b"\x00\x01\x00\x00", b"true", b"OTTO"):
    if sig == b"wOFF":
        kind, n, start, step = "WOFF", struct.unpack(">H", data[12:14])[0], 44, 20
    else:
        kind = "OpenType (CFF)" if sig == b"OTTO" else "TrueType"
        n, start, step = struct.unpack(">H", data[4:6])[0], 12, 16
    tags = {data[start + i * step:start + i * step + 4].decode("latin-1") for i in range(n)}
    missing = sorted(REQUIRED - tags)
    print(f"{kind} with {n} tables: {', '.join(sorted(tags))}")
    print("missing required tables: " + ", ".join(missing) if missing else "all required tables present")
else:
    print("not a font: starts with", sig.hex())

Run against this file, it prints: WOFF2 with 10 tables, Brotli-compressed: read further with fontTools