CAD Kernel in Rust faster than SMLib

ONE DOCUMENT one undo stack

ELECTRONICS schematic · board · harness

Placement is poseMove a footprint on the board and the part moves in the 3D assembly. The board editor and the model share one undo step.

A wire is a wireDraw a connection on the wiring diagram and it becomes a real harness in the model, with cut lengths and its own BOM line.

One fileSchematic, board, harness and solids are blocks in the same .BREP.json — not linked files that drift apart.

What is next.BREP.io?

next.BREP.io is a unified mechanical CAD (MCAD) and electronics CAD (ECAD) platform built from the ground up in Rust. Constrained sketches, parametric features, assemblies and electronics workbenches share one document. The user interface, 3D viewer and geometry kernel form one codebase for native desktop and browser use. Explore kernel capabilities and supporting evidence.

Sketch, then build

Draw constrained 2D sketches on planes or model faces, then turn them into solids with Extrude, Revolve, Sweep, Path Sweep, Loft, Rib, Tube and Thicken. Primitives are there too when a cube or cylinder is all you need.

Edit and repair solids

Fillet and chamfer edges, drill countersunk, counterbored or threaded holes, shell a body, push or delete faces and let the neighbours heal, split with a plane, and combine bodies with Boolean union, subtract and intersect.

Parametric history

Every feature is a row in the History panel: edit its parameters, reorder it, or roll the model back to any step. Drive dimensions with named expressions such as width - wall * 2 and expose them through a configurator.

Sheet metal

Start from a flat tab, add flanges, contour flanges, hems, corner fillets and chamfers and cutouts, then unfold the part and export the flat pattern as DXF or SVG for the laser or the brake.

Assemblies

Place parts from the document's parts library and pin them with coincident, distance, angle, concentric, tangent and other constraints. Run an interference check, import structured STEP files as assemblies, and export the bill of materials as CSV or JSON.

Exact geometry, exact exchange

Models are true B-rep solids with analytic and NURBS surfaces, not meshes. Import STEP and IGES exactly, and bring in STL or OBJ meshes through automatic reconstruction into analytic faces. Export STEP AP214, IGES and STL.

One codebase, every platform

Interface, viewer and kernel are all Rust, rendering through wgpu. The same source builds the browser app you can launch above and the native Linux and Windows desktop binaries you can download below.

CAD automation with MCP

The native Model Context Protocol (MCP) server gives AI assistants programmatic access to CAD: open models, create and edit features, inspect geometry, export files and capture screenshots. Drive the desktop application or run headlessly to automate modelling workflows.

Your files stay local

In the browser, documents live in the browser's own IndexedDB storage and are never uploaded. Export a .BREP.json to keep a copy or move a model between machines. Desktop builds read and write ordinary files.

Design a housing, unfold sheet metal, lay out a PCB and build a wire harness in the same application. Schematic, board, symbol and pad workbenches share the solid model’s document and undo stack. Board placement drives assembly placement, and wiring connections become modelled harnesses with cut lengths and bills of materials.

Schematic and wiring diagram

Place a part, draw pin-to-pin wires, then edit them the way a router does: slide a segment, add a jog, take one back out, or make a wire follow another. Set references and net flags, and read the netlist straight out of the sheet.

Board layout

Footprints, pads, tracks and vias laid out against the board's design rules, with quarter-turn rotation and a top and a bottom side. The populated board is shown in 3D as you route it.

Symbol and pad editors

Draw a symbol's graphics and place its pins; lay out a footprint's pads and their shapes. Every command the editors have is named and grouped, which is what the app builds its toolbar and its automation surface from.

Import from KiCad

Read real KiCad 9 symbol and footprint libraries, and the 3D models that go with them. Every import reports what it could and could not read, rather than silently dropping what it did not understand.

Autorouting

Hand a route job to the autorouter and watch it report progress as it works, inside the same design rules the manual tools are held to. Route what you care about by hand and let it finish the rest.

Wire harness and BOM

A connection drawn on the wiring diagram becomes a real routed harness in the model. Each wire carries its cut length, its stock number and its own line in the bill of materials, which exports with the rest of the document's BOM.

Fabrication output

Emit the manufacturing set for the board as a single archive, so what goes to the fabricator is one file produced from the document rather than a folder assembled by hand.

Parts, not a catalogue

An electronics part is one of the document's own assembly parts carrying a symbol and a set of pads. There is no separate library to keep in step — change the part and Update Components pulls the new symbol and pads through, undoably.

Launch the main build in your browser or download it for your desktop. Preview builds let you explore individual changes on development branches.

Each entry provides a build of a development branch so you can try its changes and share feedback.

The user guide is generated from the same source tree as the application, so it describes the build you are running. The Docs button in the app's toolbar opens it too.

Release notes, progress on the kernel, and what is coming next, written by the people building it. The mailing list carries the same news, only occasionally.

Back the development of next.BREP.io and help bring browser-native CAD to more engineers and teams.

Support development, testing, documentation and infrastructure with a monthly sponsorship from $10 or a one-time contribution of your choice.

We’re seeking angel investors to help accelerate next.BREP.io development. If you’re interested in backing browser-native CAD for mechanical and electronics design, we’d like to talk.