As of July 2025, Mozilla’s Firefox stands as the only major web browser continuing to support macOS Big Sur, underscoring the challenges users face with aging operating systems.
The Shift in Browser Support
Apple’s macOS Big Sur, introduced in November 2020, marked a significant transition with its support for Apple Silicon processors. However, as technology progresses, software developers are phasing out support for older operating systems. Google Chrome ceased updates for macOS Big Sur in early 2025, and Apple’s own Safari browser has limited its support to more recent macOS versions. This leaves Firefox as the primary browser offering continued support for Big Sur users.
Mozilla’s Commitment to Legacy Systems
Mozilla has a history of extending support for older operating systems. In July 2023, Mozilla announced that users on macOS 10.12 (Sierra), 10.13 (High Sierra), and 10.14 (Mojave) would be transitioned to the Firefox Extended Support Release (ESR) 115, ensuring security updates until at least September 2024. This approach reflects Mozilla’s dedication to user security, even as other browsers discontinue support for older systems.
Implications for macOS Big Sur Users
For individuals and organizations still operating on macOS Big Sur, the dwindling support from major browsers poses significant security risks. Browsers are frequent targets for cyberattacks, and without regular updates, vulnerabilities can be exploited. Mozilla’s continued support through Firefox offers a temporary solution, but users are encouraged to consider upgrading their operating systems to maintain optimal security and access to the latest web technologies.
The Broader Context of Software Support
The tech industry’s trend of phasing out support for older operating systems is not unique to browsers. Software developers often align their support with the operating system versions that receive security updates from their manufacturers. Apple typically supports the three most recent macOS releases, leaving older versions without critical security patches. This practice emphasizes the importance of keeping operating systems up to date to ensure compatibility and security.
Conclusion
Mozilla’s Firefox remains a vital resource for macOS Big Sur users, providing necessary security updates and support. However, the broader industry trend highlights the importance of updating to newer operating systems to ensure continued support and security. Users are advised to plan for upgrades to maintain access to the latest features and protections offered by modern software.
