Bambu Lab faces open-source licensing scrutiny at FOSSY 2026

At the FOSSY 2026 conference in Vancouver, the Software Freedom Conservancy (SFC) presented a detailed case study on an ongoing violation of the Affero General Public License version 3 (AGPLv3) by 3D-printer manufacturer Bambu Lab. Speakers Bradley Kühn, Karen Sandler, and Denver Gingerich outlined how the company modified the open-source slicer PrusaSlicer to create its proprietary Bambu Studio software without providing the corresponding source code. The SFC argues that Bambu Lab has effectively circumvented the AGPLv3 network clause, a mechanism the licence was specifically designed to prevent.

The core of the allegation centres on how Bambu Studio handles proprietary components. The software dynamically loads two shared-library files built from C++ source, which communicate with Bambu Lab’s servers via a specific User-Agent string. While the company claims this string is a DMCA anti-circumvention mechanism, the SFC contends it is a thin layer that accesses extensive proprietary functionality on Bambu Lab’s servers. Under the AGPLv3, such network-based components must be released as source code, but Bambu Lab has kept them proprietary.

The dispute has extended beyond the AGPLv3. Gingerich noted that Bambu Lab is also violating the GPLv2 by failing to provide the source for a Buildroot-based Linux firmware used in some of its 3D-printer models. The SFC launched a project called "baltobu" to work around these violations, which includes mirroring the OrcaSlicer code maintained by Polish user Paweł Jarczak. Jarczak had reverse-engineered the proprietary network code, leading Bambu Lab to issue a DMCA takedown notice against his GitHub repository, which was subsequently honoured by the platform.

Bambu Lab has become a dominant player in the market, controlling an estimated 38 to 48 per cent of the segment for printers priced between $500 and $3,000. The company entered the market during the pandemic, leveraging deep pockets to leapfrog competitors and market aggressively through social media. Gingerich described the company as operating with a Silicon Valley-inspired culture that has taken shortcuts by violating copyleft licenses rather than reimplementing software from scratch.

The violation has mobilised a broader community of enthusiasts, many of whom had only a passing familiarity with free and open-source software. This engagement led to a successful fundraising campaign that exceeded its $250,000 goal, allowing the SFC to hire a full-time litigation attorney. Sandler noted that the campaign was driven by "teeny tiny donations" from a wide base of supporters, marking a significant shift in how the organisation engages with the public.

The SFC is pursuing various enforcement strategies to address the violations. These include reverse-engineering efforts to replace proprietary pieces and potential legal action based on contract law, citing the precedent of the SFC’s lawsuit against Vizio, now owned by Walmart. Other approaches under consideration include copyright lawsuits and the use of intellectual property clauses within trade agreements. The group aims to demonstrate different ways to hold companies accountable for the licenses they choose to use.