Casual Slides vs Google Slides — open-source self-hosted alternative

If you searched “open source Google Slides alternative” or “self-host alternative to Google Slides”, you should know up front: this comparison is honest about Casual Slides being earlier-stage than Casual Sheets or Casual Editor. v0.0.0 with no tagged release, no Docker image, naive WebSocket co-edit. But the pieces that ARE there are unusually deep — 93 of 99 .pptx fidelity probes passing after wave 12.

For most users today, Google Slides is the more pragmatic choice. The Casual Slides slot is for the small group of users who match its current trade-offs: self-host required, .pptx round-trip matters, and “Phase-2 spike collab is fine for now” is acceptable.

At a glance

	Casual Slides	Google Slides
License	Apache-2.0 — fully open source	Proprietary SaaS
Hosting	Self-host (no Docker image yet — runs from pnpm dev)	Google-hosted only
Price	Free; your hosting	Free for @gmail.com; Workspace $6+/user/mo
Google account	Not needed	Required
Native file format	.pptx	Proprietary; export to .pptx
Round-trip fidelity	93 of 99 probes ✅ (wave 12)	Google → .pptx loses transitions, animations, embedded media
Real-time co-edit	Phase-2 spike only — naive WebSocket broadcast, single-active-editor sufficient	Yes, mature OT-based
Office-style ribbon	Yes — Home / Insert / Design / Transitions / Animations / Slide Show / View / Review	Different UX (single toolbar, file-menu-driven)
Layout templates	6 (title / title+content / two-content / comparison / blank / section-header)	14+
Theme picker	Yes (theme color + font scheme)	Yes
Background picker	Solid + gradient fills	Same + image backgrounds
Slide Show mode	F5, keyboard navigation	F5, presenter view with timer + notes
Speaker notes	Notes panel	Same + presenter view
Animations	OOXML attrs round-trip; rendering still in waves	Built-in
Transitions	OOXML attrs round-trip; rendering still in waves	Built-in
PDF export	Wave 8+ planned	Yes
Mobile	Desktop-only today	Native iOS + Android
Backend	104-line raw ws server (Phase-2 spike)	Google’s stack
Maturity	v0.0.0 · pre-tag · active development	15+ years
Build on top	Apache-2.0 + Univer OSS — clean React component	Closed

Where Casual Slides is the right answer today

Read this list as “if all of these apply, Casual Slides is worth a serious look right now”:

• You need to keep .pptx files on your servers. Sales decks with non-public pricing, board decks, IP-sensitive technical diagrams — anything you wouldn’t upload to Google Drive.
• You need .pptx round-trip integrity. Google Slides converts to its proprietary format and re-exports with documented losses (animations, transitions, embedded video, custom XML, specific master-slide inheritance). Casual Slides is 93/99 ✅ on per-tag round-trip — the file you save is byte-equivalent for the OOXML surface we cover.
• You’re building on top of a presentation editor. The editor is a React component on top of Univer OSS (Apache-2.0). You can embed it without negotiating a commercial license, no AGPL obligations.
• You’re OK with single-active-editor co-edit today. The v0.0.x collab is a 104-line ws broadcast server — sufficient for the typical “I’m presenting, my co-presenter is making occasional tweaks” pattern, not safe for concurrent editing on the same slide.

Where Google Slides is the right answer today

For most users, this is the right answer. Be honest about why:

• You want a Docker image you can docker pull. Casual Slides doesn’t have one yet (lands with v0.1.0, same release as the Yjs/Hocuspocus migration).
• You need real co-edit. Multiple users editing concurrently in the same deck — Casual Slides isn’t safe for this today (single-active-editor sufficient is the explicit design point).
• You depend on the Google ecosystem. Google Drive, Forms, Slides API, Gemini integration, Workspace permissions — all SaaS-only.
• You need native mobile. Google’s iOS + Android apps work offline; Casual Slides is desktop-only today (mobile back-port is on the v0.1.0 roadmap).
• You want presenter view + timer + speaker notes during a live presentation. Google Slides has the full presenter toolkit; Casual Slides has Slide Show mode but not the full presenter view yet.
• You want a marketplace of templates + add-ons. Google has it; Casual Slides ships 6 layout templates and that’s all today.

What “93 of 99 fidelity probes” means

Casual Slides tracks a structured .pptx fidelity matrix at docs/FIDELITY_TRACKER.md. Each probe is a specific OOXML PresentationML feature (e.g., “<a:rPr><a:highlight> text highlight,” “<a:bodyPr rot> text-box rotation,” “tables as IPageElement”). Each gets labelled ✅ (round-trips), ⚠️ (partial), or ❌ (dropped).

Wave 12 (the latest snapshot) shows 93 ✅, 6 partial. The remaining 6 are documented individually — typically exotic gradient fills, certain animation triggers, and some master-slide inheritance edge cases. The full matrix lists each one with effort estimate.

Compare to Google Slides: there’s no public matrix. Behaviour is “good enough” for most files but the exact list of what survives re-export to .pptx is observable only by testing your own deck. For pipelines where you need the file to flow web edit → desktop PowerPoint → web again, Casual Slides’ explicit matrix is more useful than a vague “mostly compatible” claim.

What ships in the editor today

• Office-style ribbon with all the standard PowerPoint tabs: Home, Insert, Design, Transitions, Animations, Slide Show, View, Review.
• Slide-panel thumbnails on the left rail with reorder, duplicate, hide, delete, new (via right-click context menu).
• 6 layout templates picked from the toolbar Layout dropdown.
• Theme picker + background picker (solid + gradient).
• Slide Show mode (F5) with keyboard navigation.
• Notes panel for speaker notes.
• Recent files dialog backed by IndexedDB.
• Properties dialog + About dialog.
• 2 493 LOC pptx-import.ts covering deep OOXML PresentationML: slides, layouts, masters, themes, theme colour resolution, placeholder inheritance, gradient fills, text outline
  • arrowheads + effects, hyperlinks via custom ranges, tables + charts as IPageElement, picture backgrounds, hidden slides, text wrap, autofit, body rotation, image cropping, connectors, RTL, strikethrough/baseline, bullets + indent + line spacing, multi-run rich text + paragraph alignment, colour modifiers + rotation + flips.

It’s a real editor. It just hasn’t earned its v0.1.0 yet.

What’s deferred to v0.1.0

• Yjs + Hocuspocus migration. Today’s 104-line raw ws server gets replaced with the same Fastify + Hocuspocus stack the sheets repo ships at v0.2.x (see the production-readiness pipeline for what that buys: replay retry + dead-letter, per-IP rate limit, room cap with LRU eviction).
• Docker image (multi-arch amd64 + arm64).
• WOPI host integration + JWT auth + admin panel — lifted wholesale from the sheets repo.
• Mobile lane — viewer + light editor on ≤480 px.
• PDF + ODP export.
• Presenter view with current/next slide + speaker timer.
• Animation + transition rendering beyond round-trip.

Cost — when it’d matter

Casual Slides has no Docker image today, so the “self-host cost” math is theoretical. When v0.1.0 ships with the Docker image, expect roughly the same shape as the sister projects:

• 50 users on a small team: ~$15/mo VPS vs $300/mo Workspace Business Basic. ~20× difference.
• 200 users on a mid team: ~$40/mo vs $1 200/mo. ~30×.

These assume the Yjs migration lands with the same broadcast characteristics measured for sheets in the capacity model. Until v0.1.0 ships, this is forecast, not measurement.

When to choose what

Pick Casual Slides if:

• You need .pptx round-trip integrity.
• You can wait for v0.1.0 for production co-edit (or your shape is single-active-editor).
• You want to embed a presentation editor in your own app (Apache-2.0).
• You’re OK running from source today (no Docker image yet).

Pick Google Slides if:

• You want a finished product today.
• You need real concurrent co-edit.
• You depend on the Google ecosystem.
• You need native mobile.
• You want presenter view + animations rendered.

For most users today: Google Slides. For the subset where self-host + .pptx integrity matter and the v0.1.0 timeline works: Casual Slides is worth following.

Try Casual Slides

The live demo is at https://slide.schnsrw.live/. Source is at github.com/schnsrw/slides.

For local development:

git clone git@github.com:schnsrw/slides.git
cd slides
pnpm install
pnpm dev:web    # http://127.0.0.1:5373

The Docker image lands with v0.1.0. Watch the product page for release notifications.