This PowerPoint alternative is a single HTML file. A Bento deck carries
its own viewer, presenter, and editor inside the document — open it in any
browser, edit it, present it, send it. The person you send it to needs
nothing: the file is the software.
Try it in 10 seconds: open bento.page/slides
— that’s the entire app, running on a starter deck that doubles as the
feature tour. Or grab a designed template from the
gallery and make it yours.
Download the app: grab the single Bento_Slides.bento.html from the
GitHub Releases page or straight
from bento.page
(~560 KB, no account, no installer). Open it in any modern browser and it is
the editor. Save, and it rewrites itself with your deck inside.
Why this exists
Office documents used to be things you had. Now they’re things you rent —
locked in someone’s cloud, behind someone’s login, readable only while a
company keeps its servers on. Bento takes the other path:
- One file, forever. Deck, fonts, images, charts, animations, and the
full editor travel together. A copy from 2026 will open in 2036.
- View-source honest. Your data sits in a plain, readable JSON block at
the top of the file. No binary formats, no lock-in, no archaeology.
- It saves itself. The file rewrites its own data block on save (File
System Access API, with a download fallback). No app to install, ever.
- Local-first, provably. Flip on Offline mode and nothing leaves your
machine — updates and collaboration are hard-blocked, and the app says so.
What’s inside
| Feature |
Description |
| Morph presenting |
Elements that share an id animate between slides — position, size, color, even gradients. Duplicate a slide, rearrange, and the motion designs itself. |
| Live collaboration |
E2EE (AES-GCM) with keys that live in your file, never on a server. The file itself is the invitation: anyone who opens a copy joins. Offline edits merge back precisely — our own CRDT, character-level text merging included. |
| A blind relay |
The optional sync relay (server/sync-worker/) stores ciphertext and learns nothing. Read the source; it’s about one file. |
| Charts, built in |
Bar / line / pie / scatter drawn by our own dependency-free engine, live during presentations: tooltips, zoom, and data that morphs when a bar chart becomes a pie. |
| Designed for AI |
The document is plain JSON in the file, so agents edit .bento.html files in place and chatbots round-trip the JSON (window.bento.loadDoc). See docs/agents.md. |
| Signed self-updates |
Releases are ECDSA-signed and offered in-app. Updating writes a new file — the old one stays as your rollback. No server ever touches your documents. |
| Everything else |
Speaker view, comments, layouts, hidden interactive states, hover reveals, motion paths, PDF export, page sizes, 8 UI languages — in a ~560 KB shell. |
Use it with AI
Because the document is plain JSON living in one plaintext block near the top
of the file, any assistant that can read and write a file can edit your deck —
no plugin, no API. Two ways in:
- File harnesses edit the
#bento-doc JSON in place:
Claude Code, Cursor, Aider, or any agent
with filesystem access. Claude Code users get a packaged bento-slides
skill (installable from this repo’s plugin marketplace: /plugin marketplace add nyblnet/bento) that even downloads the latest Bento app by itself.
- Chat round-trip for any chatbot: copy the document JSON out (Save →
Copy document JSON), let the assistant rewrite it, paste it back.
It works fully offline with local open-weight models — point
Ollama, llama.cpp, or LM Studio at the deck and nothing
leaves your machine. The agent guide is a single page you can drop into any
model’s context: bento.page/agents.md (also in
this repo at docs/agents.md).
Architecture in one paragraph
slides/src/model.ts defines the JSON document model; one renderer
(render.ts) draws it for the editor canvas, thumbnails, and present mode
(Reveal.js drives navigation; morphs are computed from the model, not the
DOM). Animation is an in-house engine (anim.ts), charts are in-house
(charts.ts), collaboration is an in-house CRDT (sync/crdt.ts — pure
data, fuzz-tested by scripts/test-sync.ts across hundreds of thousands of
convergence checks). The shell compresses to ~560 KB with the document block
left as plaintext so old files and outside tools can always splice it. The
deep dive: docs/architecture.md.
Security model, honestly
- Collab keys are minted client-side at document creation and live only in
the file. Possession of the file = membership; “Rotate keys” = revocation.
- The relay sees: ciphertext, connection timing, and a hash of the room key.
It cannot read content, names, or structure.
- Presence names are claims, not proofs — fine within a shared-key room;
enterprise identity would need signed frames (designed, not built).
- Update checks fetch a static manifest and send nothing about you or your
document. Signature + hash + version monotonicity are verified in-app.
- Known trade-offs: undo during live collab is snapshot-based and can revert
a collaborator’s concurrent edit to the same property; editing is
desktop-first (phones view and present well).
Build from source
Node 20+ and npm are all you need — the app is a single-page build with no
backend to stand up.
cd slides
npm install
npm run dev # dev server (http://localhost:5173)
npm run build:single # → dist-single/Bento_Slides.bento.html (the product)
node scripts/test-sync.ts runs the CRDT convergence rig. Releases are cut
locally so the signing key never leaves the maintainer’s machine — see
docs/RELEASING.md.
Where to read more
- CLAUDE.md — the deep architecture + development guide (also what
AI agents read to work in this repo).
- docs/architecture.md — how a
.bento.html file is
built, the on-disk format, and the runtime layout.
- docs/format.md — the normative
bento/slides document-model
spec (every element type, slide/state/layout shape, and collab fields).
- docs/collab-design.md — the CRDT, E2EE relay, and
signed-write RBAC design + threat model.
- docs/agents.md — the document format, for AI agents.
- CHANGELOG.md — the version history.
- Layout:
slides/ is the app (source in slides/src/);
server/sync-worker/ is the blind relay; docs/ and scripts/ are the
guides and build tooling.
Contributions welcome — start with CONTRIBUTING.md. Found a
security issue? See SECURITY.md.
Planning a substantial contribution? Check the pinned What’s in flight
issue and the open PRs first, and say what you’re planning before you build it
— see CONTRIBUTING.md.
Roadmap
bento/slides is the first app — a PowerPoint alternative, shipping now.
bento/spaces (notes), bento/dash (sheets & tables) and bento/vault
follow, each as its own self-contained .bento.html distributable. The
current release lives on bento.page and reaches every
existing file through the signed update channel.
License
Bento is open source under the MIT License — all software here is
MIT, © 2026 The Bento authors, except the bento/id directory service in
server/directory/, which is
AGPL-3.0-only. Bundled runtime components (reveal.js,
Moveable, Selecto) are MIT; the embedded typefaces (Fraunces, Instrument Sans)
are OFL; gallery imagery is public-domain (see
scripts/gallery-photos/SOURCES.md). Each component keeps its own license.
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