Beamer+

Beamer+ is a local, browser-based presentation tool for interactive lectures. It renders PDF slide decks (e.g. LaTeX Beamer output) and layers live features on top: pen and highlighter annotations (draw and hold to snap a shape), embedded video / audio / 3D models, interactive widgets (calculators, plotters, Python REPLs, maps, …), and real-time audience surveys with AI-powered response summarization.

Everything runs from a single Flask server — on your machine for solo use, or hosted by your university for multiple concurrent lectures. Each presenter creates a session and works at /s/{code}/; audience survey QR codes point to URLs under that same session prefix.

Quick start

Requires Python 3.10+.

pip install -r requirements.txt
python launch.py            # production launcher: HTTPS with a self-signed cert

Open the https://... URL the launcher prints, then New Session on the welcome screen (or Try Demo; or go directly to /s/{code}/ if you already have a code). Browsers warn about the self-signed certificate — click Advanced → Proceed. HTTPS is needed so camera/microphone widgets work on LAN addresses.

For development there is a lighter entry point:

python app.py               # ad-hoc HTTPS cert (needs `cryptography`)
python app.py --http        # plain HTTP (camera widget disabled on LAN)

To try the built-in demo presentation (with a guided tour), click Try Demo on the welcome screen.

Loading a presentation

A new session starts with the Open window (see below); you can also drag a file onto the window. Either way, load:

• A plain PDF — every page becomes a slide.
• A presentation ZIP — a PDF plus saved configuration, media and widgets (see below). The in-app editor can add media/widgets to slides and save the result back out as a ZIP.

Presentation ZIP format

presentation.zip
├── slides.pdf                  # required — the slide deck
├── config/
│   ├── slide-order.json        # slide sequence: pdf pages, blank slides, split views, hidden flags
│   ├── s<N>.json               # per-slide config: embedded videos/audio/models/widgets + layout
│   ├── annotations.json        # saved pen strokes per slide
│   └── widget-states.json      # widget state snapshots so widgets resume where they left off
└── assets/ video/ models/ …    # media referenced by the configs

An ai/ folder in a ZIP (older decks may have one) is ignored: opening a deck never runs code from it. Summarizer models live on the server (see Custom models).

What Save writes

Save (see below) can write two files, plus any screen recordings:

• Presentation (ZIP) — everything above, to reopen and keep presenting.
• Notes (PDF) — one flat PDF to hand out. Every visible slide (hidden slides are skipped; a split view prints its two slides) with pen annotations drawn on; a split widget's two halves, each on its own slide; each widget as it stands at that moment; videos as a still frame, 3D models as a rendered picture, audio as a labelled bar; and poll results. A widget can add pages of its own right after its slide (the circuit sandbox prints its board; the notebook prints every cell; the Python workspace prints its program, shell transcript and memory diagram; an open-ended poll lists every answer). Widgets that don't describe how to print are printed as a plain snapshot of their content. Built in the browser with pdf-lib; PDF slides are copied as vector pages, so their text stays selectable. The pages Beamer+ sets itself use the slides' Computer Modern faces (static/vendor/fonts, the TTF form of the subset in fonts-cm.css; fontkit embeds them) and the widgets' palette.

Sessions

The welcome screen offers New Session (the Open window comes up, and stays until a presentation is open) and Try Demo (the demo presentation with a guided tour).

Two buttons top-right run the session: Edit (once a presentation is open) and Close Session, which asks whether to save first, then goes back to the start page.

Opening and saving: folders on this computer

Open and Save work like a file manager, each on a folder you choose once: the folder you open presentations from, and the folder you save them in (your course folder for both, say, or two different ones; the first time, Save offers Use as a one-click choice). Both are remembered across sessions, along with the subfolder you were last in; after the browser restarts it asks once to allow each again (Chrome's Allow on every visit skips that). Beamer+ doesn't impose a layout: you choose where things go. Change folder… picks another. Underneath, Or upload from somewhere else instead (Open) is the system file picker, and Or download instead (Save) saves to your browser's downloads folder.

• Open lists the folders and the .zip / .pdf files in the one you're in; click one to open it. Dropping a file on the window opens one too.
• Save (from Close Session) starts where the presentation was last saved (or the folder it was opened from, when that's inside the save folder), otherwise where you last saved. Pick a folder, a file name, and tick what to save (Presentation, Notes, Recordings); each goes in that folder:
  • <name>.zip: the presentation, which reopens at the slide you were on
  • <name>.pdf: the notes PDF (so don't name it after a slides PDF in the same folder, or the notes replace it)
  • <name>-<yyyy-mm-dd>-<hh-mm>[-part<n>].mp4 (or .webm): recordings not saved yet

Choosing a folder needs the File System Access API (Chrome, Edge). In other browsers Open is the file picker and Save downloads.

tests/browser/flow_sessions.py walks through all of this.

This is the beginning of the README. Read the rest at the original. Read the full README ↗