Free 3D Block Builder

Everything sits on a grid, so nothing ever ends up floating at a strange angle. A tap places a block against the face you are pointing at, which means you build outward from what is already there — the same way you would with real blocks.

The multi-block tools save a lot of clicking. Fill makes a solid box between two corners, Hollow box makes the same shape with the middle left out — walls, a floor and a roof in two clicks — and Line runs a straight run of blocks between any two points.

Drag to orbit, scroll to zoom, and hold Shift while dragging to slide the view sideways. The Home, Top, Front, Side and Iso buttons snap to a fixed angle, which is the quickest way to line something up when you have got yourself turned around.

A blueprint shows a target shape as flat front, side and top views, and you rebuild it. The check is by shape and it allows for position, so building the arch in a different corner still counts — but a shape buried inside a solid cube does not, because the extra blocks are counted too.

There are twelve, from a three-step staircase to a fourteen-high tower, and a different one is set as the Daily each day.

Mirroring is the single biggest time-saver for anything with a front. Turn on left–right and a face, a robot or a building facade builds both halves at once; four-way mirroring turns a few blocks into a tower or a piece of pattern work.

Stone, wood, glass, metal, grass, sand and water each have their own surface — glass and water are see-through, metal catches the light, stone and wood have a fine grain. All of it is generated in the shader, so there are no texture files to download.

Plain colour gives you the palette instead, for when you want something to be exactly the colour you have in mind.

Your build saves itself on this device as you go. Save the project as a .zblocks file to keep a copy or send it to someone, and export a PNG of the current view to share a picture of it.

Do I need to install anything?

No. It runs in the browser using WebGL2, the 3D support already built into modern browsers. There is no plugin, no account, and your build is saved on your own device.

It says 3D is not available — what now?

That means WebGL2 is switched off or unsupported. It is almost always fixed by turning hardware acceleration back on in your browser settings, or by updating the browser. Some older phones and locked-down work machines cannot run it at all.

How do I build on a phone?

Tap to place a block and drag to look around. If you keep placing blocks by accident while trying to turn the view, switch to Camera mode — then dragging only moves the camera and nothing is ever placed.

How big can a build be?

Three world sizes: 16, 32 or 64 cubes on each side, with a ceiling of 60,000 blocks in total. The cap is there so a phone does not run out of memory halfway through something you care about.

What is symmetry for?

It mirrors every block you place across the middle of the world, so a face, a tower or a robot builds both sides at once. Four-way mirroring is good for patterns and towers; left-right is what you want for anything with a front.

What are blueprints?

A target shape shown as flat front, side and top views, which you rebuild. The build is checked by shape, and it does not matter where in the world you put it — the same arch in a different corner still counts. There is a new one each day.

Can I save and share what I make?

Save the project as a .zblocks file to keep or send on, and export a PNG image of the current view. Both are produced on your device; nothing is uploaded.

Is this related to any commercial building toy or game?

No. Zerdly Blocks is an original voxel sandbox — plain geometric shapes and procedural materials, with no connection to, or resemblance to, any branded construction toy or game.

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