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Editor + Viewer vs Pure Renderer

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FIG-001

SHEET 01 / 07

FIG-002 / OVERVIEW

at a glance.

Compare Carta and @humanspeak/svelte-markdown: a Svelte markdown editor and viewer versus a focused Svelte 5 renderer with caching and HTML filtering.

FIG-003 / FEATURE MATRIX

side-by-side.

Every surface that matters, compared without spin.

feature	@humanspeak/svelte-markdown	Carta
Svelte 5 Native	yes	yes
TypeScript Support	yes	yes
Markdown Rendering	yes	yes
Markdown Editing	no	yes
Custom Renderers	Svelte components	Via plugins
Token Caching	yes	no
HTML Tag Control	84 tags with allow/deny	Via rehype-sanitize
LLM Streaming Mode Carta offers live preview for editing, but its docs do not describe a dedicated markdown streaming renderer mode.	writeChunk() / resetStream()	no
Streaming HTML Output Carta is an authoring editor with live preview, not a renderer for streaming agent output with nested HTML.	Partial blocks reconcile when </tag> arrives	no
Syntax Highlighting	Via marked extensions	Built-in plugin
Math (KaTeX)	Built-in extension (markedKatex)	Built-in plugin
Diagrams (Mermaid)	Built-in extension (markedMermaid)	Built-in plugin
Split-Pane UI	no	yes
Keyboard Shortcuts	no	yes

FIG-004 / STRENGTHS

where each shines.

▣ svelte markdown 12

+Svelte 5 runes-native — built for runes, not retrofitted
+TypeScript-first with full type safety
+Built-in token caching (50-200x faster re-renders on repeated content)
+LLM streaming with imperative writeChunk() / resetStream() API
+23 markdown renderers + 84 HTML tag renderers — every override is a Svelte snippet
+First-class extensions: KaTeX math, Mermaid diagrams, GitHub alerts, footnotes
+Built-in XSS protection — protocol allowlist, event-handler stripping, attribute sanitization
+Allow/deny utilities (allowHtmlOnly, excludeRenderersOnly, etc.) for fine-grained control
+Drop-in component — works anywhere in your Svelte app
+Simpler API — one component, one prop
+More granular HTML control (84 individual tag renderers)
+Snippet overrides for inline customization

▢ carta 5

+Full markdown editing experience with live preview
+Svelte-native (not a wrapper around another framework)
+Lightweight compared to ProseMirror-based editors
+Plugin system for syntax highlighting, math, etc.
+Keyboard shortcuts and toolbar

FIG-005 / LIMITATIONS

where each falls short.

▣ svelte markdown 5

−Smaller community (newer project)
−Runtime-only (no build-time optimization)
−No editing capabilities
−No split-pane UI
−No built-in code syntax highlighting (use a marked extension)

▢ carta 4

−Bundled editor code even if you only need rendering
−Smaller community than established editors
−No token caching
−Fewer HTML tag renderers

FIG-006 / VERDICT

the honest call.

Choose Carta when you need a Svelte-native markdown editor with live preview — it is the lightest editor option in the ecosystem. Choose @humanspeak/svelte-markdown when you only need rendering — simpler, lighter, with better caching and HTML control.

FIG-007 / MORE