Atlas Forge
Carve a messy sheet of mismatched sprites into a uniform atlas. Each one scaled to fit, exported with a JSON frame map.
Atlas Forge takes one source image full of randomly sized, randomly placed sprites and turns it into a clean uniform-grid atlas. Set the cell size (the box every sprite gets fitted into, say 300 by 100). Drag a box over each sprite and it becomes a frame, scaled to fit the cell without distortion, with a green numbered marker dropped on the source so you can see what you have already grabbed. Rotate or flip any frame to make it sit right in the box. Export the packed grid as a PNG, and the frame coordinates as a JSON map your game can index directly.
AI art tools and asset packs hand you one big sheet of sprites at every size and orientation. A grid-locked sheet packer cannot help, because it assumes every tile is already the same size. Atlas Forge is built for the messy case: free-drawn regions, each contain-fitted into a uniform cell, so a tall fish and a wide fish end up in identically sized frames you can blit by index.
- 01Drop a source image (png, jpg, webp). Transparent backgrounds work best.
- 02Set the cell size, the box every sprite is fitted into. Default is 300 by 100.
- 03Drag a box over a sprite. It becomes a frame instantly, scaled to fit, with a green numbered marker.
- 04Click a marker to select it, then rotate (R), flip (F), nudge, resize at the corners, or delete (Delete).
- 05Scroll to zoom, hold Space to pan, while you work across the sheet.
- 06Export PNG for the packed grid, and Export JSON for the frame coordinates.
- Every sprite is contain-fitted, so it is scaled down to fit the cell and centered, never stretched.
- Use the lock-to-cell-aspect toggle if you want each box to match the cell shape exactly, edge to edge.
- Backgrounds are not removed. Start from transparent PNG art, or run the sheet through BG Forge first.
- The JSON map lists each frame index with its x, y, width, and height in the exported PNG.
- Nothing leaves your machine. No upload, no server, no account.
How is Atlas Forge different from Sheet Forge?
Sheet Forge is a grid composer: it assumes every tile is already the same size and snaps to a fixed grid. Atlas Forge is for sprites of different sizes and orientations on one sheet. You draw a box around each one and it is scaled to fit a uniform cell. Reach for Atlas Forge when your source sprites are not already uniform.
Does it stretch my sprites to fill the cell?
No. Each sprite is contain-fitted: scaled down to fit inside the cell and centered, with transparent padding around it. Aspect ratio is always preserved. Turn on lock-to-cell-aspect if you would rather frame edge to edge.
Can I rotate sprites that are facing the wrong way?
Yes. Select a frame and rotate it 90 degrees at a time, or flip it horizontally or vertically. This matters for wide cells like 300 by 100, where a vertical sprite needs a quarter turn to fill the box.
What does the JSON export contain?
A frame map: cell width and height, column count, total count, and an array of frames with each index and its x, y, width, and height in the exported PNG. Your game does frames[id] and blits the region.
Does it remove the background from my sheet?
Not yet. If your source has a solid background it gets carried into each frame. Start from transparent PNG art, or run the sheet through BG Forge first. Color knockout is on the roadmap.
Does my image get uploaded anywhere?
No. The image stays in your browser tab. Capture, fitting, and export all run on a canvas, and you download the results directly.
Your AI forgets. Astryke doesn’t.
These tools stay free. Astryke Hub is the one you pay for: a board your coding agent reads at the start of a session and writes back to at the end, so it never opens cold again.
Start free14 days free, no card. Founding price $12 a month after that.