URBGEN Open the app

Parametric building design, in the browser.

Draw a plot, place buildings on it, and change a slider to rebuild any of them — massing, a facade with real openings, and metrics that show their working.

Open the app

Free. No account, and nothing is uploaded.

The app in use: a sidebar of parameters on the left, and an L-shaped eight-storey building with balconies standing on its drawn plot, a metrics panel below it.

Courtyard · 8 floors · 3.2 m module Height 24 m

What it does

The app open on the Massing tab: a sidebar of parameters on the left, and an L-shaped eight-storey building standing on its plot in the viewport.
The Massing tab, open on an L-shaped building.

Massing from presets you can then take apart

Six footprints — bar, L, T, U, courtyard and stacked — each composed from masses with their own size, floor count and base level.

Where two wings meet, the junction is detected floor by floor, so an internal elevation goes blank instead of being drawn twice.

The Facade tab: sliders for module width, window width and height, sill height and reveal, with projecting balconies selected, beside the building they shape.
Module width, window dimensions, reveal depth, and projecting balconies.

A facade driven by the apartment module

Window rhythm comes from the module width, so the bays always divide evenly across an elevation rather than leaving a remainder at one end.

Openings are real geometry, with reveals and sills, and balconies are either projecting slabs or recessed loggias.

The Site tab: plot area and corner count, a button to draw a new boundary, and five planning rules each set to zero, beside a plot drawn on the ground with draggable corners.
The plot, its corner handles, and the five planning rules.

A site, not just one building

Draw the plot boundary, or drop in a map or site plan, set its true scale from two known points, and trace over it.

Place as many buildings as you like, rotate and drag them, and watch clashes, off-plot corners and five planning rules as you go.

The facade, in detail

A plan section through a wall: on the left a window opening with its reveal and jambs dimensioned, on the right a loggia recessed between two cheeks with a soffit over.
Window reveal with jambs, left. Loggia between its cheeks, right.

This is the part a massing tool usually skips, and it is the reason the output is worth looking at. Reveals have jambs. Loggias have cheeks and a soffit. Every elevation can be overridden on its own, so the street face need not match the courtyard face.

None of it is cut out of a solid. Openings are built as panels around the void, which keeps the geometry clean enough to carry into another application.

Metrics that show their working

The metrics panel: GFA, plot ratio, coverage, NIA with its percentage, core area as a share of GFA, an estimated unit count and the tallest height, then the same broken down for one building.
GFA, plot ratio, coverage, NIA with the core taken off, and a unit estimate.

GFA, NIA, facade area, footprint, coverage, plot ratio and a unit estimate, all recomputed as you change anything. Where two wings overlap at a junction, the shared area is counted once rather than twice.

NIA takes the core off the geometry that is actually there, then applies an efficiency factor you set — it is not a percentage guessed at the end. The unit count is an estimate from the module width, and the app says so where it shows it.

Setback, separation, height cap, floor area ratio and coverage are checked in the same pass and reported with both numbers: the limit, and what the scheme does. A limit set to zero is off, so nothing inherits a rule nobody asked for. The whole table exports as CSV.

Why it is different

  • Facade depth

    Real openings with reveals and jambs, loggias with cheeks and soffits, and per-elevation overrides. Most tools at this stage give you a box with a texture on it.

  • The same inputs give the same building

    Every choice that could be random runs through a seeded generator, so a scheme rebuilds byte for byte. When the job is comparing options, that is the difference between a comparison and a coincidence.

  • No account, no cloud

    It is a static page. There is nothing to sign up for, nothing to upload, and once it has loaded it keeps working without a connection. Schemes are files on your own machine.

  • Metrics you can audit

    Every figure comes from the geometry on screen, and the corrections — the junction overlap, the core area — are ones you can check by hand.

What it does not do

Worth knowing before you spend an afternoon in it. None of these are hidden in the app either.

  • No IFC export. Geometry comes out as glTF, which is a visualisation format — you cannot pick a project up from it in Revit or ArchiCAD. This is the known gap, and the largest one.
  • No floorplans, corridors, stairs or lifts. A core is modelled as a shaft, because it takes volume and comes off the net area. What happens inside it is not drawn.
  • No environmental simulation. No daylight, shadow, wind or energy analysis of any kind.
  • Flat ground only. No terrain, no slope, no cut and fill.
  • No neighbouring buildings as context. The site holds what you place on it and nothing else.
  • No collaboration. One person, one browser. Schemes are shared by sending the file.
  • The unit count is an estimate. It comes from the module width and the floor area, not from a laid-out plan.
  • No cost estimation.

How it works

  1. Draw the plot

    Click out a boundary, or drop in a map or site plan, set its scale from two known points, and trace over it.

  2. Place and shape

    Add buildings, drag and rotate them, pick a footprint, then work the sliders — floors, depth, module, balconies, cores.

  3. Take it away

    Export the geometry as glTF, the metrics as CSV, and the whole scheme as a JSON file you can reopen later.

Questions

Do I need an account?

No. There is no sign-up, no login and no trial. Open the page and it is there.

Where does my data go?

Nowhere. There is no backend to send it to. Everything is computed in your browser, and a scheme is saved by downloading a JSON file to your machine. The site you are reading sets no cookies and makes no third-party requests.

Does it work offline?

Once the page has loaded, yes — the app keeps working with the network gone, because nothing it does needs a server.

What can I export?

glTF for the geometry, including the whole site with its buildings named; CSV for the metrics table; JSON for the scheme itself, which reopens with everything as you left it. There is no IFC export yet.

Is it really free?

Yes, and there is no pricing page to read. It is a static page with no running cost behind it beyond hosting.

Is there AI in it?

No. It is parametric: you set the numbers and the geometry follows from them, the same way every time. The name is short for urban generator, and that is as far as the word goes — nothing here learns, predicts or invents.

Open it and draw a plot

It takes about a minute to find out whether it suits the way you work.

Open the app