Contributing to Flutter

tl;dr: join Discord, be courteous, follow the steps below to set up a development environment; if you stick around and contribute, you can join the team and get commit access.

Welcome

We invite you to join the Flutter team, which is made up of volunteers and sponsored folk alike! There are many ways to contribute, including writing code, filing issues on GitHub, helping people on our mailing lists, our chat channels, or on Stack Overflow, helping to triage, reproduce, or fix bugs that people have filed, adding to our documentation, doing outreach about Flutter, or helping out in any other way.

We grant commit access (which includes full rights to the issue database, such as being able to edit labels) to people who have gained our trust and demonstrated a commitment to Flutter. For more details see the Contributor access page in our docs.

We communicate primarily over GitHub and Discord.

Before you get started, we encourage you to read these documents which describe some of our community norms:

Our code of conduct, which stipulates explicitly that everyone must be gracious, respectful, and professional. This also documents our conflict resolution policy and encourages people to ask questions.
Values, which talks about what we care most about.

Helping out in the issue database

Triage is the process of going through bug reports and determining if they are valid, finding out how to reproduce them, catching duplicate reports, and generally making our issues list useful for our engineers.

If you want to help us triage, you are very welcome to do so!

Join the #hackers-triage Discord channel.
Read our code of conduct, which stipulates explicitly that everyone must be gracious, respectful, and professional. If you're helping out with triage, you are representing the Flutter team, and so you want to make sure to make a good impression!
Help out as described in our triage guide You won't be able to add labels at first, so instead start by trying to do the other steps, e.g. trying to reproduce the problem and asking for people to provide enough details that you can reproduce the problem, pointing out duplicates, and so on. Chat on the #hackers-triage channel to let us know what you're up to!
Familiarize yourself with our issue hygiene wiki page, which covers the meanings of some important GitHub labels and milestones.
Once you've been doing this for a while, someone will invite you to the flutter-hackers team on GitHub and you'll be able to add labels too. See the contributor access wiki page for details.

Quality Assurance

One of the most useful tasks, closely related to triage, is finding and filing bug reports. Testing beta releases, looking for regressions, creating test cases, adding to our test suites, and other work along these lines can really drive the quality of the product up. Creating tests that increase our test coverage, writing tests for issues others have filed, all these tasks are really valuable contributions to open source projects.

If this interests you, you can jump in and submit bug reports without needing anyone's permission! The #quality-assurance channel on our Discord server is a good place to talk about what you're doing. We're especially eager for QA testing when we announce a beta release. See quality assurance for more details.

If you want to contribute test cases, you can also submit PRs. See the next section for how to set up your development environment, or ask in #hackers-test on Discord.

As a personal side note, this is exactly the kind of work that first got me into open source. I was a Quality Assurance volunteer on the Mozilla project, writing test cases for browsers, long before I wrote a line of code for any open source project. —Hixie

Developing for Flutter

If you prefer to write code, consider starting with the list of good first issues for Flutter or for Flutter DevTools. Reference the respective sections below for further instructions.

Framework and Engine

To develop for Flutter, you will eventually need to become familiar with our processes and conventions. This section lists the documents that describe these methodologies. The following list is ordered: you are strongly recommended to go through these documents in the order presented.

Setting up your engine development environment, which describes the steps you need to configure your computer to work on Flutter's engine. If you only want to write code for the Flutter framework, you can skip this step. Flutter's engine mainly uses C++, Java, and Objective-C.
Setting up your framework development environment, which describes the steps you need to configure your computer to work on Flutter's framework. Flutter's framework mainly uses Dart.
Tree hygiene, which covers how to land a PR, how to do code review, how to handle breaking changes, how to handle regressions, and how to handle post-commit test failures.
Our style guide, which includes advice for designing APIs for Flutter, and how to format code in the framework.
Flutter design doc template, which should be used when proposing a new technical design. This is a good practice to do before coding more intricate changes. See also our guidance for writing design docs.

In addition to the documents, there is a video linked above on How to contribute to Flutter from the Flutter YouTube channel, there are many pages in our docs, and an article Contributing to Flutter: Getting Started on Medium that may be of interest. For a curated list of pages see the sidebar on the wiki's home page. They are more or less listed in order of importance.

DevTools

Contributing code to Dart & Flutter DevTools may be a good place to start if you are looking to dip your toes into contributing with a relatively low-cost setup or if you are generally excited about improving the Dart & Flutter developer experience.

Please see the DevTools CONTRIBUTING.md guide to get started.

Helping with existing PRs

Once you've learned the process of contributing, if you aren't sure what to work on next you might be interested in helping other developers complete their contributions by picking up an incomplete patch from the list of issues with partial patches.

Outreach

If your interests lie in the direction of developer relations and developer outreach, whether advocating for Flutter, answering questions in fora like Stack Overflow or Reddit, or creating content for our documentation or sites like YouTube, the best starting point is to join the #hackers-devrel Discord channel. From there, you can describe what you're interested in doing, and go ahead and do it! As others become familiar with your work, they may have feedback, be interested in collaborating, or want to coordinate their efforts with yours.

API documentation

Another great area to contribute in is sample code and API documentation. If this is an area that interests you, join our Discord server and introduce yourself on the #hackers-devrel, #hackers-framework, or #hackers-engine channels, describing your area of interest. As our API docs are integrated into our source code, see the "developing for Flutter" section above for a guide on how to set up your developer environment.

To contribute API documentation, an excellent command of the English language is particularly helpful, as is a careful attention to detail. We have a whole section in our style guide that you should read before you write API documentation. It includes notes on the "Flutter Voice", such as our word and grammar conventions.

In general, a really productive way to improve documentation is to use Flutter and stop any time you have a question: find the answer, then document the answer where you first looked for it.

We also keep a list of areas that need better API documentation. In many cases, we have written down what needs to be said in the relevant issue, we just haven't gotten around to doing it!

We're especially eager to add sample code and diagrams to our API documentation. Diagrams are generated from Flutter code that draws to a canvas, and stored in a special repository. It can be a lot of fun to create new diagrams for the API docs.

Releases

If you are interested in participating in our release process, which may involve writing release notes and blog posts, coordinating the actual generation of binaries, updating our release tooling, and other work of that nature, then reach out on the #hackers-releases channel of our Discord server.

Social events in the contributor community

Finally, one area where you could have a lot of impact is in contributing to social interactions among the Flutter contributor community itself. This could take the form of organizing weekly video chats on our Discord, or planning tech talks from contributors, for example. If this is an area that is of interest to you, please join our Discord and ping Hixie on the #hackers channel!