# May in Servo: user scripts, mp4 compat, blackboxing in DevTools, and more!

DevFeed: [May in Servo: user scripts, mp4 compat, blackboxing in DevTools, and more!](<https://devfeed.tech/articles/may-in-servo-user-scripts-mp4-compat-blackboxing-in-devtools-and-more-3545.md>)

Original publisher: [Read original article](<https://servo.org/blog/2026/06/30/may-in-servo/>)

Author: The Servo Project Developers

Published: 2026-06-30T00:00:00Z

Content type: release

Language: en

Sources: [Servo Blog](<https://devfeed.tech/sources/servo-blog.md>)

Topics: [servo](<https://devfeed.tech/topics/servo.md>), [Web platform](<https://devfeed.tech/topics/web-platform.md>), [Document Object Model (DOM)](<https://devfeed.tech/topics/dom.md>), [Memory Safety](<https://devfeed.tech/topics/memory-safety.md>), [API](<https://devfeed.tech/topics/api.md>), [Security](<https://devfeed.tech/topics/security.md>), [Forms](<https://devfeed.tech/topics/forms.md>), [Accessibility](<https://devfeed.tech/topics/accessibility.md>), [Nix](<https://devfeed.tech/topics/nix.md>), [webgpu](<https://devfeed.tech/topics/webgpu.md>)

Tags: [developers](<https://devfeed.tech/tags/developers.md>), [forms](<https://devfeed.tech/tags/forms.md>), [html](<https://devfeed.tech/tags/html.md>), [memory-safety](<https://devfeed.tech/tags/memory-safety.md>), [release](<https://devfeed.tech/tags/release.md>), [rust](<https://devfeed.tech/tags/rust.md>), [security](<https://devfeed.tech/tags/security.md>), [servo](<https://devfeed.tech/tags/servo.md>), [servo-engine](<https://devfeed.tech/tags/servo-engine.md>), [servo-rendering-engine](<https://devfeed.tech/tags/servo-rendering-engine.md>), [web-browser](<https://devfeed.tech/tags/web-browser.md>), [web-browser-engine](<https://devfeed.tech/tags/web-browser-engine.md>), [web-engine](<https://devfeed.tech/tags/web-engine.md>), [web-platform](<https://devfeed.tech/tags/web-platform.md>), [web-rendering-engine](<https://devfeed.tech/tags/web-rendering-engine.md>), [webgpu](<https://devfeed.tech/tags/webgpu.md>), [windows](<https://devfeed.tech/tags/windows.md>)

## AI overview

Servo 0.3.0 summarizes 391 commits made in May, adding web platform and DOM API support, improving forms and media compatibility, and fixing build issues on Windows, FreeBSD, and Nix environments. The release also includes memory safety fixes through a SpiderMonkey update, experimental Sanitizer improvements, IndexedDB changes, DevTools work, and ongoing WebGPU, accessibility, and performance development.

## Source excerpt

Servo 0.3.0 contains all of the changes we landed in May, which came out to 391 commits (April: 534). For security fixes, see § Security. We've shipped several new web platform features: 'font-kerning: none' (@simonwuelker, #44634) 'font-variant-east-asian' (@simonwuelker, #44989) 'font-variant-ligatures' (@simonwuelker, #44903) 'font-variant-numeric' (@simonwuelker, #44950) 'font-variant-position' (@simonwuelker, #45142) mp4 files without fast start in <video> (@calvaris, #45084) <form enctype="multipart/form-data"> (@yezhizhen, #45028) <form enctype="text/plain"> (@yezhizhen, #45111) <![CDATA[]]> layout (@mrobinson, #44791) Plus a bunch of new DOM APIs: onslotchange property on ShadowRoot (@jdm, #44688) screenLeft and screenTop on Window (@TG199, #45128) new Blob() with {endings: "native"} (@yezhizhen, #44803) new PerformanceMark() (@shubhamg13, #44702) parseHTML() on Document (@kkoyung, #44952) readAsBinaryString() on FileReader (@yezhizhen, #44858, #44921) performance.measure() with mark values 'redirectStart', 'redirectEnd', 'secureConnectionStart', and 'responseEnd' (@shubhamg13, #44673, #44624, #44850, #44739) We've also fixed some build issues on Windows (@mukilan, #45079), FreeBSD (@delan, @mrobinson, @mukilan, #44600), and for anyone building Servo on NixOS or with Nix (@freyacodes, #45051, #45135). This is another big update, so here's an outline: Security - memory safety fixes Work in progress - execCommand(), Sanitizer, IndexedDB, accessibility, workers Embedding API - MSRV, cookies, preferences, diagnostics For users and developers - --host-file, --userscripts, DevTools Debugger More on the web platform - focus, forms, navigation, SubtleCrypto, WebGPU Performance - about:memory, threads, layout, DOM, build times Stability - crashes, hangs, static analysis Security Servo's JS runtime, SpiderMonkey 140.10.0, had several memory safety bugs that have been fixed in Servo 0.3.0 with the update to SpiderMonkey 140.10.1 (@jschwe, #44755). For mor