# DevTools 2.21.1 release notes

> Release notes for Dart and Flutter DevTools version 2.21.1.



The 2.21.1 release of the Dart and Flutter DevTools
includes the following changes among other general improvements.
To learn more about DevTools, check out the
[DevTools overview](https://docs.flutter.dev/tools/devtools).

## Performance updates

* Replace the DevTools timeline trace viewer with
  the [Perfetto](https://perfetto.dev/) trace viewer -
  [#5142](https://github.com/flutter/devtools/pull/5142)

  ![perfetto trace viewer](/assets/images/docs/tools/devtools/release-notes/images-2.21.1/image1.png "perfetto_trace_viewer")

* Fix several issues with loading a Performance snapshot into DevTools -
  [#5048](https://github.com/flutter/devtools/pull/5048),
  [#4929](https://github.com/flutter/devtools/pull/4929)
* UI polish and cleanup - [#4889](https://github.com/flutter/devtools/pull/4889)

## Memory updates

* Improve usability of snapshot diffing -
  [#5015](https://github.com/flutter/devtools/pull/5015)
* UI polish and cleanup -
  [#4855](https://github.com/flutter/devtools/pull/4855)
* Color code classes based on where they are defined
  (SDK, your package, dependencies, etc.) -
  [#5030](https://github.com/flutter/devtools/pull/5030)
* Fix state management issue for tracing -
  [#5062](https://github.com/flutter/devtools/pull/5062)
* Improve the performance of taking a heap snapshot -
  [#5134](https://github.com/flutter/devtools/pull/5134)
* Retire broken import/export feature -
  [#5135](https://github.com/flutter/devtools/pull/5135)

## Debugger updates

* Added support for viewing profiler hits in
  the debugger script viewer -
  [#4831](https://github.com/flutter/devtools/pull/4831)
* Added support for inspecting records -
  [#5084](https://github.com/flutter/devtools/pull/5084)

## General updates

* Fix several issues in syntax highlighting that would
  color variable names that contain reserved words incorrectly and
  leave `extends`/`implements` clauses uncolored for some classes -
  [#4948](https://github.com/flutter/devtools/pull/4948)
* Fix an issue in Safari, and
  other browsers that do not support RegExp negative lookbehind,
  that prevented DevTools from loading -
  [#4938](https://github.com/flutter/devtools/pull/4938)
* Fix an issue that would prevent DevTools connecting to
  the backend server that would disable some functionality -
  [#5016](https://github.com/flutter/devtools/pull/5016)
* Add a link to the DevTools
  [contribution guide](https://github.com/flutter/devtools/blob/master/CONTRIBUTING.md)
  to the About menu, and fixed the Discord link -
  [#4926](https://github.com/flutter/devtools/pull/4926)
* Fix conflicting colors in light theme -
  [#5067](https://github.com/flutter/devtools/pull/5067)

## Full commit history

To find a complete list of changes since the previous release,
check out
[the diff on GitHub](https://github.com/flutter/devtools/compare/v2.20.0...v2.21.1).