Aseprite JSON to PixiJS — Tags Become Animations
Load an Aseprite JSON into PixiJS and you get textures but no animations: its Spritesheet reads the frames and leaves meta.frameTags and each frame's duration unused. Drop the JSON with its PNG here and re-export for PixiJS 8: the tags become an animations map in playback order, slice pivots become anchors, and the milliseconds are kept for AnimatedSprite.
- PixiJS 8Verified· PixiJS 8.21
- Godot 4Verified· Godot 4.7.2
- Unity 6Verified· Unity 6000.5.3f1
- Phaser 3 / 4Verified· Phaser 3.90 + 4.2
- Aseprite JSONVerified· Phaser load.aseprite · 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
- Reads Aseprite JSON in hash or array layout with its frameTags (direction, repeat) and per-frame durations, together with the sheet PNG.
- An animations map with one entry per tag, frame keys in playback order, so reverse and ping-pong play right with no extra code.
- An anchor per frame from its pivot: the pivot slice in the file, or the one you place with P.
- meta.nerulio.animations keeps fps, loop, direction and durationsMs for every tag; the README shows how to build an AnimatedSprite with those times.
- Several pages are linked with related_multi_packs and load together; scale variants get their own meta.scale.
How to do it
- Drop the Aseprite JSON and its PNG together.
- Check the tags on the Timeline and move pivots with P where the anchors should differ.
- Open Pack & Export and choose PixiJS 8; rotation is allowed for this target.
- Export, load the JSON with Assets.load and build an AnimatedSprite from sheet.animations with the times in meta.nerulio.
Aseprite JSON fields and their PixiJS 8 counterparts
| Aseprite JSON | PixiJS 8 spritesheet JSON | What PixiJS does with it |
|---|---|---|
| frames[…].frame | frames[key].frame on the new page | texture region |
| spriteSourceSize, sourceSize | the same fields | trim offset respected |
| frames[…].duration | meta.nerulio.animations[tag].durationsMs | nothing on its own; pass as AnimatedSprite times |
| meta.frameTags from, to, direction | animations[tag] in playback order | sheet.animations[tag] gives the textures |
| frameTags repeat | meta.nerulio.animations[tag].loop | set loop on the sprite yourself |
| meta.slices pivot | frames[key].anchor | the texture's default anchor |
| meta.image, one page | meta.image per page plus related_multi_packs | the other pages load with the first |
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
Does PixiJS read Aseprite's frameTags?
No. Its Spritesheet makes textures from the frames only, so an Aseprite JSON gives you no animations in PixiJS. This export writes the animations map that PixiJS does read.
How do I play the frames at their own durations?
Read durationsMs from meta.nerulio.animations[name] and pass {texture, time} pairs to new AnimatedSprite, as the README in the export shows. Set TextureSource.defaultOptions.scaleMode to 'nearest' for pixel art.
Was the PixiJS output checked?
Yes: PixiJS 8.21 loaded and drew this target's files, rotated and multi-page atlases included.
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).