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Oculith Draw Foundation

NewFor Linux, built on Omarchy

Free, open-source construction PDF markup and drawing review, built in Rust. Open construction PDFs, mark them up, measure them and compare revisions on your own machine. No account, no subscription, no network.

Get Foundation on GitHub Compare editions
  • LinuxAvailable now
  • WindowsInstaller coming soon
  • macOSInstaller coming soon

Free and open source · LGPL-3.0 · built in Rust · your markups live in the PDF

00Why we build it

Tools for the future of construction, on Linux.

Oculith is dedicated to building the tools for the future of construction workflows on Linux: fast, open, and owned by the people who use them. Oculith Draw is the start. A drawing set should open on any machine, stay in a file you control, and never sit behind a subscription to be read.

Open by defaultThe Foundation edition is LGPL-3.0, with its full source, a file-by-file manifest and a bill of materials on every release.
Linux firstBuilt and used daily on Omarchy. Linux is a first-class desk for construction, not an afterthought.
Your files, your machineThe PDF is the record. Markups and take-off live in the file, and nothing needs the cloud to work.
01What it does

The full review tool. Not a viewer.

Sheets, markups, takeoff, compare and raceways in one desktop app, built for the way construction sets are actually read.

01

Sheets and sets

Open PDF drawings in tabs with thumbnails, bookmarks and layers. Register every page as a sheet, record revisions, relink moved files after a fingerprint check, and publish the current set as one PDF in sheet order.

02

Markups

Lines, arrows, boxes, clouds, callouts, text, highlights, counts, stamps and an offline library of construction symbols. Tool Chest presets, sequences, hot keys and Drawing Mode make repeated work fast.

03

Markups List

A searchable, sortable spreadsheet of every markup, with layers, status and Text, Choice, Number, Checkmark and Formula columns. Edit in place, export CSV or a PDF summary.

04

Measuring

Length, polylength, area, perimeter, angle and count against a calibrated scale, with the title-block scale detected and offered. Any unit, imperial or metric.

05

Compare

Side-by-side or overlaid revisions with confirmed page pairs, a change list and CSV or PDF reports. Turn detected changes into editable markups.

06

Raceways

Conduit and cable-tray runs with standard elbows, pull points, risers, a raceway schedule, bend totals and fill aids.

07

Spaces, layers, schedules

Name spaces, sort markups into layers, and place quantity schedules on the sheet as tables.

08

OCR and CAD

Add a text layer to scanned sheets with Tesseract, and import DWG or DXF geometry.

Everything is saved in the PDF itself, as standard annotations, so your markups open in other PDF readers too.

02Two editions

Start free. Grow into Apex.

One drawing tool, two editions. Both run entirely on your machine.

FoundationFree · open source

Oculith Draw Foundation

The full drawing and review tool, licensed under the LGPL-3.0. It needs no account, no subscription and no network connection.

  • Sheets, sets and revisions
  • Markups, Tool Chest and the Markups List
  • Calibrated measuring and takeoff
  • Revision compare with change reports
  • Raceways, spaces, layers and schedules
  • OCR and DWG / DXF import
  • Every release ships with a source manifest and an SBOM
Get it on GitHub
ApexFor electrical teams

Oculith Draw Apex

Everything in Foundation, plus Apex: custom tools built for the electrical industry, delivered as plugins. They run locally, beside the app, with no cloud, no login and no GPU.

  • Everything in Foundation
  • Electrical tools, such as take-off and device counts on electrical drawings
  • Tools for conduit, cable and wire runs, panel schedules and one-lines
  • QA/QC markups that connect to the Oculith platform
  • Support from the team that builds it

Apex tools are proprietary plugins. They are copyrighted by Oculith, licensed separately, and are not part of Oculith Draw Foundation. They are not covered by Foundation's LGPL-3.0 license and are not included in its source code. Foundation is complete and free on its own; Apex plugins load on top of it.

Talk to us about Apex
03Built for Linux

Linux first. On purpose.

Oculith Draw is built for Linux today. It is developed and used every day on Omarchy, DHH's beautiful, opinionated Arch Linux and Hyprland setup. Thanks to the Omarchy project for a desktop that makes a drawing tool a joy to build on. Get Omarchy at omarchy.org.

  • LinuxAvailable now · build from source
  • WindowsInstaller coming soon
  • macOSInstaller coming soon
~/oculith-foundation · omarchy
$ git clone https://github.com/GhostTekz/oculith-foundation
$ cd oculith-foundation/open-pdf-studio
$ npm ci
$ npm run tauri:community -- --no-bundle
✓ built target/community/oculith-draw
$
Needs Node.js 26, stable Rust and the Tauri 2 platform libraries. The full list is in the README.
04Engineering choices · built in Rust

Small, fast and exact.

The core is Rust: rendering, geometry, CAD import and OCR run natively, inside a Tauri 2 shell, so the app starts fast and stays light on memory.

Local-first

The PDF on disk is the source of truth. Markups, layers and custom columns are written into the file, not a hidden database.

Tauri 2, not Electron

The system WebView and a Rust core keep the installer small and memory low. Rendering, geometry, CAD and OCR are native Rust.

Three PDF engines

PDFium draws the pixels, PDF.js reads text and annotations, pdf-lib writes saves. PDFium runs in its own worker, so a broken PDF can't take the app down.

Page coordinates everywhere

Geometry lives in PDF page space, with crop box and rotation part of the save contract. A markup lands in the same place on a rotated or cropped sheet.

Exact measuring

Computed from page geometry and the calibrated scale, with no snapping or silent rounding. Units and precision only change how a value is shown.

Reproducible source

Every release carries a per-file SHA-256 manifest and a CycloneDX bill of materials of every locked Cargo and npm dependency.

05Built on open source

Standing on good work.

Oculith Draw grew from Open PDF Studio by the OpenAEC Foundation, and stands on the projects below. Hats off to every maintainer and contributor: go and give them a star.

Credited with thanks. Listing these projects doesn't mean they endorse or are affiliated with Oculith; each is the work of its own authors under its own license.

Every locked dependency is listed in SBOM.cdx.json, and the full third-party notices ship with the app.

06In plain terms

Free construction PDF markup, in plain terms.

What Oculith Draw is, what it costs, and where it runs. For the rest of the job, see the Oculith platform.

What is Oculith Draw?

A desktop app for reviewing construction drawings: open PDF sets, mark them up, measure and take off quantities, and compare revisions, all on your own machine.

Is it really free?

Yes. Oculith Draw Foundation is free and open source under the LGPL-3.0. It needs no account, no subscription and no network connection.

Which platforms does it run on?

Linux today, built from source. Windows and macOS installers are coming soon.

Is it an alternative to Bluebeam Revu?

It is a free, open-source option for the same core review work: markups, a Markups List, calibrated measuring and takeoff, revision compare and raceways, on Linux. Oculith is not affiliated with Bluebeam, Inc.; Bluebeam and Revu are its trademarks.

Where are my markups kept?

In the PDF itself, as standard annotations, so they open in other PDF readers too. The file on disk is the record, not a hidden database.

What does Apex add?

Proprietary plugins with tools for the electrical industry, such as take-off and device counts on electrical drawings. They are licensed separately and are not part of Foundation.

Open a set. Mark it up.

Foundation is free. Apex is a conversation.

Get Foundation on GitHub Ask about Apex