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What’s new in Svelte: April 2026

MCP in OpenCode, functions in config and error boundaries on the server

Dani Sandoval

This month, a new best practices guide was added to the Svelte docs. Check it out, if you haven't already!

On the code side, the Svelte MCP got even easier to use with improvements to the official OpenCode package. Combined with the improvements to svelte.config.js, server-side error boundaries in SvelteKit and better types all around, this month is full of great improvements!

As always, there's plenty in the showcase too!

What's new in Svelte and SvelteKit

  • MCP: Svelte's OpenCode config can now be found in sv's .opencode/ folder - including the generated svelte.json plugin config (sv@0.12.6, Docs, #977)
  • svelte.config.js now contains functions for setting certain options (css, runes, customElement) so that there's a single source of truth for everything that needs to interact with Svelte config (svelte@5.54.0, Docs, #17951)
  • svelte/motion now exports TweenOptions, SpringOptions, SpringUpdateOptions and Updater - these types cover the public method signatures of spring and tweened (svelte@5.55.0, Docs, #17967)
  • Error boundaries are now allowed to catch errors on the server (kit@2.54.0, Docs, #15308)
  • Page and layout params with matchers are now type narrowed in $app/types - leading to better type safety when working with params in $app/types, $app/state, and hooks (kit@2.55.0, Docs, #15502)

For a full list of changes - including all the important bugfixes that went into the releases this month - check out the Svelte compiler's CHANGELOG. Looking for more details on the many bug fixes and performance optimizations from this month? Check out the SvelteKit / Adapter CHANGELOGs.

Community Showcase

Apps & Sites built with Svelte

  • Ghostty Config is a beautiful intuitive configuration generator for Ghostty terminal
  • Orbit PDF is a professional, high-performance PDF toolkit that runs entirely in your browser
  • Estimate Quest is a game-inspired planning poker experience that helps Scrum Masters and Product Managers run structured, actually engaging estimation sessions
  • Deltaray is a free and open source web app to simulate how light refracts and reflects on surfaces, using real physics and optical calculations
  • Nabu is a modular, local-first and open source block editor engine
  • bizi is a better way to manage dependent concurrent tasks
  • Vyay is a minimalist google sheet powered expense racker
  • ElyOS is a full-featured desktop experience powered by web technologies
  • Plought is a collection of decision making applications that use different methods to evaluate alternatives against each other
  • otel-gui is a lightweight, zero-config OpenTelemetry trace viewer for local development
  • Nodepod is a free, open source alternative to WebContainers
  • VariantCAD is a hybrid CAD system for variant generation

Learning Resources

Featuring Svelte Contributors and Ambassadors

This Week in Svelte

Libraries, Tools & Components

  • svelte-realtime is a realtime RPC and reactive subscriptions for SvelteKit, built on svelte-adapter-uws
  • itty-sockets is an ultra-tiny WebSocket client that pairs (optionally) with a public relay server
  • Motion GPU is an easy way for writing WGSL shaders in Svelte
  • ptero is a Docusaurus for Svelte
  • Svelte Audio UI is a set of accessible, composable audio UI components
  • Svelte Agentation is a dev-mode Svelte inspector for source-aware element inspection and browser annotations
  • cross-router is a framework-agnostic router that wires the core's navigation state into that framework's reactivity model
  • SVG to Svelte quickly converts SVG strings directly in Svelte components

That's it for this month! Let us know if we missed anything on Reddit or Discord.

Until next time 👋🏼!