Apple highlights cross-browser compatibility progress in 2025

Apple's WebKit team has published a comprehensive report highlighting the company's progress in cross-browser compatibility through the Interop 2025 initiative, an industry-wide effort that has dramatically improved web standards compliance across all major browsers.

Safari's dramatic improvement

The most striking achievement was Safari's performance, which Apple reports made "the largest jump of any browser this year, climbing from 43 to 99." This represents a nearly 130% improvement in just one year, showcasing Apple's significant engineering investment in web standards.

According to Apple's analysis, the Interop 2025 project focused on 20 key areas spanning CSS, JavaScript, Web APIs, and performance. The results were remarkable: while only 29% of selected tests passed across all browsers at the beginning of 2025, that pass rate skyrocketed to 97% by year's end.

Industry-wide collaboration

Interop 2025 was a collaborative effort involving major industry players including Apple, Bocoup, Google, Igalia, Microsoft, and Mozilla. The initiative aimed to "improve interoperability in 15 key areas that will have the most impact on web developer experience."

Apple emphasized the collaborative nature of the process: "Each year, the Interop project chooses its focus areas through a collaborative process with proposals, research into what web developers need, and debates about priorities."

Experimental browser performance

Perhaps most impressively, all four experimental browsers reached near-perfect compatibility. Chrome Canary, Edge Dev, Firefox Nightly, and Safari Technology Preview all achieved 99% compatibility by the end of the year, demonstrating that cutting-edge browser versions are now operating at an exceptionally high standard of web standards compliance.

Focus areas for 2026

Looking ahead to Interop 2026, Apple has identified three particularly meaningful focus areas:

• Anchor positioning - A CSS feature that allows developers to position elements relative to other elements
• Same-document View Transitions - Enabling smooth transitions between different states within the same page
• Navigation API - Providing more control over browser navigation and history management

Comprehensive contributions across 19 focus areas

Beyond the headline-grabbing improvements, Apple's WebKit team made contributions across all 19 focus areas and five investigation areas. These spanned multiple domains:

CSS and UI improvements:

• @scope - A new way to limit the scope of CSS selectors
• backdrop-filter - Applying visual effects behind elements
• text-decoration - Enhanced control over text styling

API enhancements:

• Storage Access API - Improving cookie access in third-party contexts
• URLPattern - A more powerful way to match URLs
• Accessibility testing - Better tools for ensuring web accessibility

Additional areas:

• Gamepad API testing - Improving game controller support
• Mobile testing - Ensuring better performance on mobile devices

Why this matters for developers

The dramatic improvement in cross-browser compatibility has significant implications for web developers. With browsers now operating at 97-99% compatibility for core web standards, developers can spend less time writing browser-specific workarounds and more time building features.

This convergence also means that progressive enhancement strategies become more reliable, and the risk of "works on Chrome but not Safari" scenarios decreases substantially.

The future of web standards

Apple's report suggests that the web is moving toward a more unified ecosystem where core standards work consistently across all major browsers. This represents years of collaborative effort paying off, with the technical debt of browser-specific implementations gradually being eliminated.

For Apple specifically, the dramatic improvement in Safari's compatibility score demonstrates the company's commitment to web standards and its willingness to invest significant engineering resources in areas that benefit the entire web ecosystem, not just Apple's platforms.

The full report from Apple's WebKit team provides detailed technical insights into each focus area and the specific challenges overcome during the year, offering a fascinating look at the behind-the-scenes work that makes modern web development more consistent and predictable.