Bento — the office suite that fits in a file

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

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.

Community

• Questions and help — Discussions → Q&A
• Ideas and feature requests — Discussions → Ideas
• Built something with Bento? — Show and tell
• Bugs — open an issue. Security issues go through SECURITY.md instead, never a public issue.

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. 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.