Uppy is an open source project by Transloadit
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Uppy development

Fork the repository into your own account first. See the GitHub Help article for instructions.

After you have successfully forked the repo, clone and install the project:

git clone [email protected]:YOUR_USERNAME/uppy.git
cd uppy
npm install

Our website’s examples section is also our playground, please read the Local Previews section to get up and running.

Requiring files

  • If we are require()ing a file from the same subpackage (e.g. require @uppy/dashboard/utils/hi.js from @uppy/dashboard/src/index.js) - we can freely use relative imports, as long as the required file is under the src directory (/:packageName/src/**/*.js).
  • But if we want to require some file from another subpackage - we should use global @uppy requires, and they should always be in the form of @uppy/:packageName/(lib instead of src)/(same path).js


Unit tests are using Jest and can be run with:

npm run test:unit

For end-to-end tests, we use Webdriverio. For it to run locally, you need to install a Selenium standalone server. Just follow the guide to do so. You can also install a Selenium standalone server from NPM:

npm install selenium-standalone -g
selenium-standalone install

And then launch it:

selenium-standalone start

After you have installed and launched the selenium standalone server, run:

npm run test:endtoend:local

By default, test:endtoend:local uses Firefox. You can use a different browser, like Chrome, by passing the -b flag:

npm run test:endtoend:local -- -b chrome

Note: The -- is important, it tells npm that the remaining arguments should be interpreted by the script itself, not by npm.

You can run in multiple browsers by passing multiple -b flags:

npm run test:endtoend:local -- -b chrome -b firefox

When trying to get a specific integration test to pass, it’s not that helpful to continuously run all tests. You can use the --suite flag to run tests from a single ./test/endtoend folder. For example, --suite thumbnails will only run the tests from ./test/endtoend/thumbnails. Of course, it can also be combined with one or more -b flags.

npm run test:endtoend:local -- -b chrome --suite thumbnails

These tests are also run automatically on Travis builds with SauceLabs cloud service using different OSes.


Before doing a release, check that the examples on the website work:

npm start
open http://localhost:4000/examples/dashboard

Also check the other examples:

cd examples/EXAMPLENAME
npm install
npm start

Releases are managed by Lerna. We do some cleanup and compile work around releases too. Use the npm release script:

npm run release

If you have two-factor authentication enabled on your account, Lerna will ask for a one-time password. There is an issue with the CLI where the OTP prompt may be obscured by a publishing progress bar. If Lerna appears to hang just as it starts publishing, chances are it’s waiting for the password. Try typing in your OTP and hitting enter.

Other things to keep in mind during release:

  • When doing a major release >= 1.0, of the @uppy/core package, the peerDependency of the plugin packages needs to be updated first. Eg when updating from 1.y.z to 2.0.0, the peerDependency of each should be "@uppy/core": "^2.0.0" before doing npm run release.
  • When adding a new package, add the following key to its package.json:
    "publishConfig": { "access": "public" }
    Else, npm will try and fail to publish a private package, because the @uppy scope on npm does not support that.

After a release, the demos on transloadit.com should also be updated. After updating, check that some things work locally:

  • the demos in the demo section work (try one that uses an import robot, and one that you need to upload to)
  • the demos on the homepage work and can import from GDrive, Insta, Dropbox

If you don’t have access to the transloadit.com source code ping @arturi or @goto-bus-stop and we’ll pick it up. :sparkles:

Website development

We keep the uppy.io website in ./website, so it’s easy to keep docs and code in sync as we are still iterating at high velocity.

The site is built with Hexo, and Travis automatically deploys this onto GitHub Pages (it overwrites the gh-pages branch with Hexo’s build at every change to master). The content is written in Markdown and located in ./website/src. Feel free to fork & hack!

Even though bundled in this repo, the website is regarded as a separate project. As such, it has its own package.json and we aim to keep the surface where the two projects interface as small as possible. ./website/update.js is called during website builds to inject the Uppy knowledge into the site.

Local previews

  1. npm install
  2. npm start
  3. Go to http://localhost:4000. Your changes in /website and /packages/@uppy will be watched, your browser will refresh as files change.

Then, to work on, for instance, the XHRUpload example, you would edit the following files:

${EDITOR} packages/@uppy/core/src/index.js \
  packages/@uppy/core/src/Plugin.js \
  packages/@uppy/xhr-upload/src/index.js \

And open http://localhost:4000/examples/xhrupload/ in your web browser.

CSS guidelines

The CSS standards followed in this project closely resemble those from Medium’s CSS Guidelines. If something is not mentioned here, follow their guidelines.

Naming conventions

This project uses naming conventions adopted from the SUIT CSS framework.
Read about them here.

To quickly summarize:


Syntax: u-[sm-|md-|lg-]<utilityName>



Syntax: [<namespace>-]<ComponentName>[-descendentName][--modifierName]

.twt-Button /* Namespaced component */
.MyComponent /* Components pascal cased */
.Button--default /* Modified button style */

.Tweet-header /* Descendents */

.Accordion.is-collapsed /* State of component */


This project uses SASS, with some limitations on nesting. One-level-deep nesting is allowed, but nesting may not extend a selector by using the & operator. For example:

/* BAD */
.Button {
  &--disabled {

/* GOOD */
.Button {

.Button--disabled {

Mobile-first responsive approach

Style to the mobile breakpoint with your selectors, then use min-width media queries to add any styles to the tablet or desktop breakpoints.

Selector, rule ordering

  • All selectors are sorted alphabetically and by type.
  • HTML elements go above classes and IDs in a file.
  • Rules are sorted alphabetically.
/* BAD */
.wrapper {
  width: 940px;
  margin: auto;

h1 {
  color: red;

.article {
  width: 100%;
  padding: 32px;

/* GOOD */
h1 {
  color: red;

.article {
  padding: 32px;
  width: 100%;

.wrapper {
  margin: auto;
  width: 940px;