[RFC] Add Svelte support to Amplify UI

[northprint]

On which framework/platform would you like to see this feature implemented?

Other

Which UI component is this feature-request for?

Authenticator

Please describe your feature-request in detail.

Description

I would like to propose adding Svelte support to Amplify UI, starting with the Authenticator component. I have a working implementation ready and would appreciate feedback before submitting a PR.

Motivation

• Svelte is growing rapidly in popularity (70k+ GitHub stars)
• Many developers have requested Svelte support for Amplify UI
• Would provide feature parity with React, Vue, and Angular implementations

Proposed Solution

I've implemented a complete Svelte package (@aws-amplify/ui-svelte) that includes:

• ✅ Full Authenticator component with all auth flows
• ✅ XState integration using existing state machines
• ✅ TypeScript support
• ✅ 95%+ test coverage
• ✅ E2E tests
• ✅ Theme system integration

Technical Details

• Uses xstate@4.33.6 (same as other frameworks)
• Follows existing component architecture
• Implements Svelte-native patterns (stores, slot props)
• Includes comprehensive test suite

Usage Example

<script>
  import { Authenticator } from '@aws-amplify/ui-svelte';
</script>

<Authenticator let:user let:signOut>
  <h2>Welcome {user.username}!</h2>
  <button on:click={signOut}>Sign Out</button>
</Authenticator>

Questions

1. Would you be open to accepting Svelte support for Amplify UI?
2. Any concerns about using XState v4 for consistency with other frameworks?
3. Preferred approach for the PR - single comprehensive PR or split into smaller ones?

Additional Context

• Implementation is complete on branch svelte/authenticator
• All components, tests, and docs are ready
• CI/CD workflows have been updated
• Happy to make any adjustments based on feedback

Would love to hear your thoughts on this proposal. Thank you!

Please describe a solution you'd like.

https://github.com/northprint/amplify-ui/tree/svelte/authenticator
https://github.com/northprint/amplify-ui/tree/svelte/authenticator/packages/svelte

We love contributors! Is this something you'd be interested in working on?

• 👋 I may be able to implement this feature request.
• ⚠️ This feature might incur a breaking change.

[bobbor]

Thank you @northprint for your work on adding svelte support to the Authenticator.

We'll take a look at the implementation and will come back to you to let you know if it is possible to go forward with the changes and create a Pull Request for them.

Please be aware that since this is a big change it might take some time to review.

[northprint]

@bobbyu99
Thank you!
First, I thought I should make a suggestion, I have not submitted a pull request, should I?

[bobbor]

hey @northprint, I think a PR is pretty useful to see the changes more clearly and allows to leave comments and have discussions.

So feel free, go ahead and create a PR. In the meantime we will continue reviewing the changes.

P.S. I think there was a small mistake about who you wanted to mention in your comment ;)

[northprint]

@bobbor
Thanks, I'll make a PR
I'm sorry, wrong mentions.