New standards available in Foxit Editor – Brotli

Foxit Commits to Brotli Compression in PDF, Starting With Reading Support

Foxit will support Brotli compression in its PDF products, starting with reading support in Foxit PDF Reader and Foxit PDF Editor. The Foxit PDF SDK will add Brotli compression as well. Brotli won't become the default compression method in Foxit products until enough PDF reading applications support it.

The starting line

In August 2026 the PDF Association published its Brotli specification for PDF 2.0. It defines the BrotliDecode filter and gives Brotli a formal path into the format. The association's announcement has the background.

Why Foxit is backing it

Foxit committed to Brotli because it's sound engineering: a well-specified, open, patent-free filter. It joins Flate and PDF's other filters as one more compression option, used where it helps. The commitment is about interoperability and keeping pace with where the format is heading. Users shouldn't notice anything different. Choices like this work best when nobody notices them.

Work since early 2025

Foxit started on Brotli in early 2025, soon after the PDF Association published its article on Brotli compression for PDF, and prepared its implementation carefully with interoperability in mind.

• March 2025: The PDF Association publishes its article on Brotli compression for PDF. Foxit begins evaluating implementation options and discussing interoperability testing with other vendors.
• March to April 2025: Foxit engineers build a proof of concept of the Brotli filter, focused on reading support and interoperability.
• April 2025: The team tests compression levels and predictor algorithms, compares efficiency with PDF's existing compression methods and checks compatibility with sample files from other vendors and PDF industry participants.
• 2025 to 2026: Collaborative testing continues, along with technical articles on Brotli's benefits and limitations and interoperability discussions across the PDF ecosystem.
• August 2026: The PDF Association publishes the specification. Foxit commits to supporting it.

Two things came out of the testing. The default Brotli compression level was too aggressive, so the team tested more practical settings. And certain predictor combinations made files larger instead of smaller.

Future rollout: reading first

A Brotli-compressed PDF won't open in a viewer that doesn't support the new filter, and that stays true until a critical mass of viewers does. So Foxit is introducing support in stages, starting with reading, instead of turning on Brotli generation everywhere at once. The aim is to keep files interoperable and keep customers clear of backward-compatibility risk.

• During 2027: Foxit PDF Reader and Foxit PDF Editor add Brotli reading support.
• Foxit PDF SDK: Adds Brotli compression.
• Later: Brotli becomes a default compression option once enough PDF reading applications support it.

Until then, Brotli stays off by default in Foxit products.