All PDF viewing software and open-source document processing libraries will require updates to support the new Brotli compression filter.
Despite being a pervasive yet often unnoticed compression format, integrated into leading browsers and CDNs for years, Brotli has not been adopted for PDF document creation and viewing. Since version 1.2 in 1996, PDFs have instead utilized the FlateDecode filter, familiar from .zip and .png compression.
However, this status quo is set to evolve. The PDF Association is nearing the release of a summer specification, providing developers with guidelines to integrate Brotli into their PDF processing tools. The expectation is for Brotli to be swiftly adopted into a forthcoming revision of the official PDF 2.0 standard, ISO 32000-2, overseen by the International Organization for Standardization.
As PDF file sizes continue to grow and enterprise data lakes amass billions more annually, the demand for superior compression techniques has become critically urgent.
Implementing Brotli compression promises significantly smaller PDF documents. Based on a 2025 assessment by Artifex Software, a PDF Association member, this could lead to an average file size reduction of 10% to 25%, varying with the content type.
Regrettably, for organizations, this marks the start of a considerable effort. Once Brotli-compressed PDFs become common, any software or associated libraries not yet updated will fail to decompress and open these files. This represents a novel challenge for PDF users: although the format has gained many new capabilities since its 2008 ISO standardization, none have previously rendered older PDFs unreadable.
Among the most apparent applications needing Brotli compatibility upgrades are commercial PDF creation and viewing tools, like Adobe Acrobat, Foxit PDF Editor, and Nitro PDF. Browser-embedded PDF viewers are also included in this requirement.
However, beneath these surface-level applications lies an extensive network of less conspicuous open-source utilities, libraries, and SDKs. These are integral to enterprise PDF workflows and automated batch processing. Identifying and updating these embedded components, frequently hidden within external libraries, is anticipated to be a protracted task.
Should businesses postpone these crucial updates, they face the likelihood of receiving Brotli-enabled PDFs that are incompatible with their legacy software. IT departments are likely to confront this issue firsthand as users report difficulties in opening files.
Integrating Brotli Functionality
Developers require an initial push to accelerate adoption, noted Guust Ysebie, a software engineer at Apryse, a document processing firm. He emphasized that “Someone needs to take the lead and generate enough momentum for others to follow suit.”
The process is challenging, as Ysebie detailed in a PDF Association website article concerning Brotli’s integration. The slow adoption stems from the PDF specification’s demand for agreement among hundreds of interested parties.
He proposed three methods to streamline this transition, with the most straightforward being a widespread awareness campaign to highlight the necessity of upgrading across various communication channels.
A bolder idea involves structuring Brotli-enabled PDFs to display a “not supported” message, prompting users to upgrade, instead of causing older readers to fail. This message would serve as a placeholder for the compressed data.
As a third strategy, Ysebie mentioned that proactive developers could undertake the task of updating open-source libraries. He confirmed he has already integrated Brotli support into various libraries, such as Apryse’s iText SDK.
“Real-world adoption typically proceeds by creating a feature informally, followed by early adopters implementing it, which then encourages its integration into larger products,” Ysebie explained. He believes the pivotal point for widespread Brotli software adoption will be its inclusion in Adobe Reader, though the exact timeline for this remains uncertain.
The optimistic outlook is that, given the finite number of software libraries requiring updates, incorporating Brotli support should be relatively simple, Ysebie stated. Nonetheless, organizations will still need to deploy these updated components within their existing applications.
Regarding Brotli’s formal inclusion in the ISO PDF 2.0 specification (a process that has been underway since 2015), Ysebie acknowledged that significant progress is still needed. However, he emphasized the industry’s imperative to evolve beyond outdated technologies. He remarked, “We must propel the ecosystem forward. Initial stages may be somewhat disorderly, but the future potential is substantial.”
This piece was originally published by Computerworld.
