Cross-platform, cross-browser screenshot testing for modern user interfaces.

What is

Happo is a visual regression testing tool. It hooks into your CI environment to compare the visual appearance of UI components before and after a change. Screenshots are taken in different browsers and across different screen sizes to ensure consistent cross-browser and responsive styling of your application. is a tool in the Testing Frameworks category of a tech stack.

Why people like

Here鈥檚 a list of reasons why companies and developers use

Add a one-liner

Here are some stack decisions and reviews by companies and developers who chose in their tech stack.

Russel Werner
Russel Werner
Lead Engineer at StackShare | 7 upvotes 8877 views
React Storybook

We use Jest because when we rebooted our "front end" stack earlier last year, we need to have a testing solution (we didn't have any front-end tests before that!). Jest is fast and convenient and it has plenty of community support behind it. It let's us run our unit tests with Enzyme and snapshot tests.

This is an area that we are constantly reviewing to see what can be improved, both in terms of developer needs, accuracy, test maintainability, and coverage.

I'm currently exploring using React Storybook to be the record of snapshot tests and using some online services, such as and Percy in our CI pipeline.

See more
Adam Neary
Adam Neary
Engineer at Airbnb | 5 upvotes 19421 views
React Storybook is a straight up life-saver. It is the only screenshot testing tool I鈥檝e ever used, so I would not be sophisticated enough to compare it to alternatives, if there are any, but the essential idea is that you push code, and it goes off and renders all the components in your PR, comparing it with the version on master.

This means if you edit a component like <Input /> it will show you the impact on components that use Input, including the Search Bar you accidentally modified. It. Is. Fabulous.

How many times did you think your change was contained only to discover that ten other teams started using what you built, and your change breaks three of the ten? Without Happo, you might not know.

Until lately, the only downside with Happo was that our React Storybook variations (the input to the screenshot testing process) did not always reflect reliable data adequately. Now that Storybook is leveraging API data, we can feel much more confident. Plus, as our demo explores, it is automatic. If you add a field to the query and then the component, Happo will automatically post the diff to your PR, letting the engineers, designers, and product managers sitting next to you see the visual consequences of the change you have made.

See more's Features

  • No more manual parsing of CSS
  • See the effects of changes directly
  • Test individual components in isolation's alternatives

  • JUnit - A programmer-oriented testing framework for Java
  • Cucumber - Simple, human collaboration.
  • Capybara - Acceptance test framework for web applications
  • RSpec - Behaviour Driven Development for Ruby
  • PHPUnit - Testing framework for PHP

See all alternatives to