Cartosmith

A battle map built for the DM.

Cartosmith is a battle map program for Windows. Run the whole encounter from one DM screen: initiative, movement, conditions, doors and spell effects. Your players watch on a second screen, or soon on their own phones.

Join the waitlist See what it does
The Cartosmith DM screen mid-encounter in a steampunk tower: a lit battle map in the centre, floor tools on the left, and an initiative list of friendly and hostile creatures on the right.
The DM Prep overlay on a castle treasury with four rooms. Doors and chests carry state markers: red for an armed trap, yellow with a padlock for locked, and green for confirmed safe.
Castle Nightspire, B8 ยท Treasury & Hidden Vault: 8 armed traps, 7 locked and 7 confirmed safe, across doors, chests and a trapdoor.

01DM Prep

Prep every trap and secret.

Mark each door, chest and trapdoor as trapped, locked or confirmed safe. Every marker takes the colour of its state, so you can read a room at a glance. The overlay is for the DM only.

  • Armed trap
  • Locked
  • Confirmed safe

02Buildings

Whole buildings, floor by floor.

Link stairs and passages between floors. See your party and enemies across the whole tower at a glance.

  • Friendly
  • Hostile
  • Active turn
Cartosmith showing the ground floor of a five-floor tower, with the building overview on the left and the initiative list on the right. The DM building overview: five stacked floor outlines, from The Threshold Concourse up to The Weave Crown, with creature markers on each floor.
The Lumen Spire, five floors with two creatures on each floor. The building overview on the right is for the DM.

03Showcase maps

Go deep. Then go up.

Cartosmith comes with four ready-to-run maps. Castle Nightspire has 32 floors, from the Ember Depths to the Spire Roofs. Brassgate stacks 13 floors of neon, brass and clockwork.

A six-pointed star of docking bays around a central hall, with an airship moored in each point.
Airship DockBrassgate, 6F
A tilted square market of neon-lit stalls around a chequered central plaza.
Undercity BazaarBrassgate, B1
An irregular many-sided hall cut into triangular rooms, lit by violet and gold coils.
Tesla GalleryBrassgate, 4F
Green glass domes linked by a winding walkway, with small workrooms at either end.
Neon ConservatoryBrassgate, 7F
Winding cave tunnels around a river of glowing lava.
The Ember DepthsCastle Nightspire, B17, the lowest of 32 floors

Every floor is a real Cartosmith map with walls, doors and line of sight. Opening one starts a fresh copy, so the original is never overwritten.

04Vision

Fog that knows what they can see.

One encounter. Two heroes across a maze of angled rooms, windows, doors and hallways.

The complete encounter on a honeycomb of hexagonal clockwork rooms, as the DM sees it, with every room and token visible.
DM view. The complete encounter.
Player 1's view: only the hexagonal room Mira stands in and a slice of the next room are visible. Everything else is dark.
Player 1, Mira. Western apiary.
Player 2's view: Rowan's room and the lines of sight through its doors and windows are visible. Everything else is dark.
Player 2, Rowan. Eastern apiary.

Brassgate, Clockwork Apiary: 24 windows and 33 doors. Same floor and token positions in every view.

05Online play

Your table, on their phones. In testing

Players open a link, type a name and wait for you to let them in. No app and no account. You still run everything from your PC.

  • Share a six-character code, a link or a QR code. You approve every player.
  • They see the rooms you have revealed, never the secrets you have not.
  • A big move pad: tap to step, hold to walk, with the feet left always shown.
  • A strip over the map says "Your turn", so nobody misses theirs.

Online play is built and in testing. It is a preview, not open to everyone yet. See where it stands.

The join page on a phone: join code K3SPAC, the name Mira, Mira's pixel-art token and an Ask to join button.
Join with a code
The player's map on a phone: their token in a revealed room, a gold Your turn strip, End turn and Reset movement buttons, and a move pad showing 30 ft.
Play on the map
The DM's Online session window: a join code, join link and QR code, Mira waiting to join with Approve, Reject and Block, and three players with their controls.
Your side. The join code, a request to approve, and who controls what.
The sprite maker: a pixel-art elf with red hair and a gold circlet on the canvas, a preview of the token on the DM's map, and the character builder with hair, colours and outfit options.

06Tokens

Bring your hero to life. In testing

Players make a pixel-art token right in their browser. Your PC keeps it with the battle, so next session their token is ready.

  • Build a hero from hair, beard, headgear, outfit and colours, or tap Surprise me.
  • Paint over it with pencil, fill, mirror and undo.
  • Or start from your own picture and turn it into pixel art with one tap.
  • You can replace, lock or reset any player's token. Simple letters work too.
  • Elf with long red hair and a gold circletMira
  • Ranger in a green hoodRowan
  • Wizard in a purple hat with blonde braidsTamsin
  • Dwarf in a steel helm with a long red beardBram
  • Grey-skinned elf with white hairYsolde
  • Fighter with auburn hair and a scarCorwin
  • Orc with a mohawk, tusks and war paintFen
  • Red-skinned tiefling with cream hornsOdessa
  • Bald old warrior with an eyepatch and grey beardThorne
  • Elf with blue braids and a gold tunicLark

Ten heroes built in the sprite maker.

07Spells

Spells that look like spells.

Fire, ice, lightning, vines and auras. Eight effects, with a hero's aura inside the cold cone.

Eight spell templates on a grid: Fireball, Cone of Cold, Spirit Guardians, Wall of Fire, Entangle, Lightning Bolt, Darkness and Web, each drawn with its own texture and labelled with its size.
Real spell templates rendered in Cartosmith, on a 5 ft grid, shown at their in-app size.
Three overlapping Cartosmith windows in different themes: a dark red-tinted theme, a deep blue theme and a light parchment theme.

08Themes

Make it yours.

Five themes, including Ravenloft, Arcane, Parchment and a High Contrast option for easy reading.

Be there when Cartosmith opens.

Leave your email and we'll let you know when it's ready.