Rebar Studio
Rebar Studio is a free, offline desktop and web app for .reb form templates:
- author templates with a live PDF preview, completions and the engine's error markers;
- fill documents from them: text, dates, choices, tables with computed totals, photos from the
camera, signatures;
- finalize documents to a locked PDF with its SHA-256 fingerprint, and export them one by one,
in batches, or as a register (CSV, JSON).
No account, no server, no network: everything stays on the device. It runs the
reb engine, the engine Rebar's server runs, compiled to
WebAssembly, so a template behaves and prints the same in Studio and in Rebar.
What is in it
| Area | What it does |
|---|
| Templates | Library with search, tags, archive, duplicate; a starter gallery of ten construction templates; versions (a template's next edit after a document uses it starts a new version, so documents never change) with restore; template images |
| Editor | Monaco with .reb snippets, the engine's errors and warnings as markers (unknown bindings, unused fields, invalid names and conditions), the compiled HTML, the schema, and the form the template produces |
| Documents | The form built from the schema; show-if conditions, formulas and validation from the engine; autosave, undo; live preview; finalize, duplicate, reopen as a revision, move a draft to the latest template version |
| PDF | Desktop: Chromium's printToPDF with the parameters Rebar sends Gotenberg (checked pixel by pixel, npm run test:fidelity). Browser: paged.js and the print dialog. Rendered pages cannot reach the network |
| Files | .reb, .rebpack (a template with its images, the format Rebar imports), .rebdoc (one document, self-contained), .rebbackup (the workspace); the desktop app and the installed web app open them |
| Offline | The web app installs as a PWA and works offline from its first visit; the desktop app is offline by nature |
| Appearance | Amber, Ocean, Forest and Violet app themes, saved in Settings |
| Updates | Desktop: electron-updater from GitHub Releases, stable or beta channel (a beta build follows the betas). With automatic updates on (the default), downloaded in the background and installed on quit; off, nothing is downloaded until asked. Web: a "reload" prompt |
Development
Requirements: Node.js 22+ and Go 1.26+ on your PATH.
npm install
npm run dev # http://localhost:5173
npm run build # dist/ (type check, app, service worker)
npm run lint
npm test # unit tests, against the real engine
npm run test:e2e # Playwright: the web build and the desktop app (build first)
npm run test:fidelity # the desktop PDF against Gotenberg (GOTENBERG_URL, default :3010)
npm run dev and npm run build first run build:wasm (scripts/build-wasm.sh), which builds the
engine release pinned in go.mod to public/rebcompiler.wasm (and its PDF form build, reb v0.6.0 and
later, to public/rebpdf.wasm, which the engine worker loads on the first fillable PDF) and copies what the engine ships for
browsers (wasm_exec.js, tailwindcss.js, paged.polyfill.js, specification.md). These files
are generated, not committed.
- Move to a new engine release:
go get -tool github.com/vanillaiice/reb/cmd/[email protected] github.com/vanillaiice/reb/cmd/[email protected]
(docs/releasing.md).
- Build against a local
reb checkout while changing the engine: REB_DIR=../compiler npm run dev.
Playwright drives its own Chromium by default (npx playwright install chromium); set
CHROMIUM_PATH=/usr/bin/chromium to use the system one.
Layout
src/
app/ shell, router, onboarding, updates, files opened from the system
engine/ the engine worker and its typed client
store/ IndexedDB: templates, versions, documents, files, settings
editor/ the template editor (loaded only when a template is opened)
form/ the form filler: fields, tables, photos, signatures
render/ rendering: the PDF and paged documents, fonts, exports
formats/ .rebpack, .rebdoc, .rebbackup
documents/ library/ settings/ reference/ starters/
electron/ main process, preload (the page's only bridge), the network-isolated PDF renderer
e2e/ Playwright tests test/ Vitest tests
Desktop app (Electron)
npm run electron:dev # build, then launch Electron
npm run electron:pack # unpacked build in release/ (fast, for testing)
npm run electron:dist # installers: AppImage and deb, NSIS and portable, dmg and zip
REBAR_STUDIO_USER_DATA=/some/folder starts the app with a separate profile (the tests use one).
Versions
Releases are tagged vX.Y.Z with gover (.gover); a tag
builds the installers (see docs/releasing.md).
Code signing policy
Free code signing provided by SignPath.io, certificate by
SignPath Foundation.
The Windows releases are signed: the installer, the portable executable and the Rebar Studio.exe
they install. Only files built from this repository are signed; the Electron and Chromium libraries
shipped next to the app keep their own signatures. Each signed file is built by the
Release workflow from a tagged commit of this repository, on
GitHub-hosted runners, and every signing request is approved by hand.
Team roles:
Privacy
This program will not transfer any information to other networked systems unless specifically
requested by the user or the person installing or operating it.
The one connection it makes is the update check of the desktop app: with Settings, Updates,
Update automatically on (the default), it asks GitHub Releases for a newer version when it starts.
Turn that setting off and Studio connects only when you press Check now. GitHub sees the request,
as it sees any download from it; see the
GitHub privacy statement.
The web app is served by GitHub Pages and, once loaded, works without a connection.
License
Rebar Studio is licensed under the GNU General Public License v3.0 or later; see
LICENSE. Copyright (C) 2026 hblabs.
The engine (rebcompiler.wasm) is built from reb, also
GPL-3.0-or-later. Bundled third-party components, all under GPL-compatible licenses:
- React, Monaco Editor, Tailwind CSS, paged.js, Electron, electron-updater, idb, fflate, marked,
lucide: MIT or ISC
- Go's
wasm_exec.js: BSD-3-Clause (the Go authors)
- Fonts (Inter, Source Serif 4, JetBrains Mono, Noto Sans Arabic): SIL Open Font License 1.1
