Aseprite to Sprite Sheet — Packed PNG with Tags Kept
Drop the .aseprite file and open Pack & Export: every frame is packed into atlas pages in a worker while you watch, identical frames are stored once, empty borders are trimmed with their offsets kept, and the tags and per-frame durations from the file travel into whichever data file your engine reads.
- Phaser 3 / 4Verified· Phaser 3.90 + 4.2
- Aseprite JSONVerified· Phaser load.aseprite · PixiJS 8.21
- Godot 4Verified· Godot 4.7.2
- Unity 6Verified· Unity 6000.5.3f1
- PixiJS 8Verified· PixiJS 8.21
- .asepriteVerified· Aseprite 1.3.18
- Spine / libGDXVerified· spine-canvas 4.2
- Starling / Sparrow XMLVerified· Phaser 4.2
- LÖVEVerified· LÖVE 11.5
- DefoldBuilt· Defold bob.jar 1.13.1
- GameMakerUNVERIFIED
- CSS spritesVerified· Chromium
- GIF / APNGDecoded· Pillow
What it does
- Packers: MaxRects with five placement rules, Skyline and Guillotine; "try all" keeps the smallest page, and the same input always gives the same bytes.
- Trim keeps each frame's size and offset; crop-keep makes frames smaller and moves the pivot so the art stays put; alias stores frames with identical visible pixels once, after a byte check.
- Pages: multipack up to 64, a limit from 8 to 16384 px, power-of-two, square or fixed sizes, border and shape padding, extrude.
- Scale variants from @0.5x to @4x, nearest-neighbour only, each its own atlas file; integer upscales are exact pixel copies.
- Aseprite JSON (hash or array) in the layout of Aseprite's own File › Export Sprite Sheet: frameTags with direction and repeat, a duration per frame, and slices for the pivot and boxes.
How to do it
- Drop the .aseprite file; the Sprite workspace reads its layers, tags and durations.
- Open Pack & Export; the sheet is packed live and redrawn after each change (Cancel stops a long pack).
- Choose your engine's preset or Aseprite JSON; a target that needs a single page or no rotation re-packs and says what changed next to its button.
- Check the Packed frames list for frames that were trimmed or stored once.
- Press Export for <target> and unzip the PNG pages and their data file into your project.
Sheet outputs from one .aseprite file
| Output | Data file | Tags and timing | Checked with |
|---|---|---|---|
| Aseprite JSON (hash or array) | <name>.json with meta.frameTags and meta.slices | from..to ranges with direction and repeat; ms per frame | Phaser 3.90 and 4.2 load.aseprite; PixiJS 8.21 frames |
| Phaser 3 / 4 | atlas JSON hash or multiatlas + .anims.json | one animation per tag, each frame's own duration | Phaser 3.90 and 4.2 |
| PixiJS 8 | spritesheet JSON with animations and anchor | playback order in animations; ms in meta.nerulio | PixiJS 8.21 |
| Godot 4 | SpriteFrames .tres + AnimatedSprite2D .tscn | speed per tag, relative durations, loop | Godot 4.7.2 |
| Generic JSON | TexturePacker-style frames, animationData, pivots, boxes | kept in its own animation fields | read as a TexturePacker hash by Phaser 3.90/4.2 and PixiJS 8.21 |
| Spine / libGDX atlas | .atlas text | none: an atlas lists regions only | spine-canvas 4.2 draws every region |
Engine exports and how each was checked
"Verified" means the exported files were loaded by the real engine or tool on real CC0 assets and the result was compared with the source. Anything that was not loaded is labelled as such.
| Target | Files | Check |
|---|---|---|
| Godot 4 | .tres SpriteFrames · .tscn AnimatedSprite2D · .png.import | Verified Godot 4.7.2Loaded by Godot; every animation frame drawn and compared with the source file. The scene uses Nearest filtering; rotation is never used. |
| Unity 6 | .unity.json · Editor/NerulioSpriteImporter.cs · AnimationClip | Verified Unity 6000.5.3f1Batch mode: sprite rects, pivots, pixels, clip keys and durations checked. |
| Phaser 3 / 4 | atlas JSON (multiatlas) · .anims.json | Verified Phaser 3.90 + 4.2Frames and animations drawn by both versions. |
| PixiJS 8 | spritesheet JSON · animations · anchor · meta.scale | Verified PixiJS 8.21Rotated and multi-page atlases included. |
| Aseprite JSON | hash / array · frameTags · slices | Verified Phaser load.aseprite · PixiJS 8.21Tags keep their direction and repeat count. |
| .aseprite | layers · tags · durations · slices | Verified Aseprite 1.3.18Opened and rendered by the Aseprite command line. |
| Spine / libGDX | .atlas | Verified spine-canvas 4.2Every region drawn by the Spine runtime, rotated and trimmed; libGDX itself was not run. |
| Starling / Sparrow XML | XML per page | Verified Phaser 4.2Phaser 3.90 draws trimmed XML frames wrongly (its own bug); the "Sparrow XML (Phaser 3)" preset turns trim off and passes in 3.90 and 4.2. |
| LÖVE | Lua quads · nerulio_atlas.lua · main.lua | Verified LÖVE 11.5Every frame drawn and every animation stepped through the shipped helper. |
| Defold | .atlas · .tilesource | Built Defold bob.jar 1.13.1Built by Defold's command-line builder; the built texture's UVs were read back. |
| GameMaker | spr_<name>_stripN.png · gamemaker.json | UNVERIFIEDNot loaded in GameMaker (no headless GameMaker). The strips are cut the way its strip importer cuts them. |
| CSS sprites | .css · preview .html | Verified ChromiumEvery class drawn from the shipped stylesheet. |
| GIF / APNG | one file per animation | Decoded PillowEvery frame and delay decoded again after export; APNG is exact. |
Evidence
Exports: 49 runs in the real engines on real CC0 assets, 47 pass — the 2 failures are Phaser 3.90's trimmed-XML bug, which the Phaser 3 preset avoids. Packer head-to-head on 5 real frame sets (CodeAndWeb free web packer, GAPTools, free-tex-packer): smallest sheet on all 5 with rotation allowed, 4 of 5 without; every frame restored pixel-exact.
Limits
- Polygon (mesh) packing is not offered: none of the verified engines draws a mesh atlas from exported data.
- GameMaker strips are UNVERIFIED in GameMaker itself.
- Scale variants (@0.5x–@4x) use nearest-neighbour only.
- Trimmed Starling XML is drawn wrongly by Phaser 3.90; use the "Sparrow XML (Phaser 3)" preset there.
Questions
Why is Aseprite JSON limited to one page?
An Aseprite JSON file describes one image, and Phaser's load.aseprite reads it that way, so this target re-packs onto a single page. For sets that need several pages, the Phaser preset writes a multiatlas and PixiJS 8 links its pages with related_multi_packs.
Why are the frame keys "0", "1", "2"?
Phaser's createFromAseprite looks frames up by number, so the export uses the --filename-format "{frame}" form. Phaser 3.90 and 4.2 loaded it with load.aseprite, and PixiJS 8.21 read its frames.
Two of my tags share frames. Is one of them lost?
No. In Aseprite JSON a tag is a from..to range, so a frame used by two tags, or a tag whose frames are out of order, gets a second entry pointing at the same region. The export notes how many entries it repeated.
Is it free, and do I need an account?
Everything on these pages is free and works without an account. There is no watermark and no export that is held back.
Are my sprites uploaded?
No. The Studio decodes, packs and exports in this browser tab. Projects are autosaved in the browser (IndexedDB) and can be saved as a .nerulio file.
Does it need Aseprite or an engine plugin installed?
No. .aseprite files are read and written in the browser, and each engine bundle carries what that engine needs (for Godot, the import settings and scene; for Unity and the Godot TileSet, a small editor script).