Question 1

Is this a free TexturePacker alternative?

Accepted Answer

Yes. GameImageToolkit Texture Atlas Packer runs entirely in your browser — no signup, no uploads. It uses MaxRects packing and exports Unity .png.meta, Godot 4 SpriteFrames .tres, TexturePacker JSON, Spine / libGDX .atlas, Phaser 3, Cocos plist and DragonBones JSON. Open it at https://gameimagekit.com/en/tool/atlas-packer

Question 2

Are my images uploaded to a server?

Accepted Answer

No. Trimming, packing, atlas rendering and metadata generation all happen locally in your browser. Files are never uploaded, so it is safe and fast.

Question 3

What is "trim" and does it lose information?

Accepted Answer

Trim removes pixels around each sprite whose alpha is below the threshold, to save space. The default of 1 only drops fully transparent pixels. Raise it to 8–16 to clip anti-aliased fringes. The exported metadata records the content offset (spriteSourceSize) and original size (sourceSize), so engines can restore the sprite to its original position losslessly.

Question 4

What is the difference between padding and extrude?

Accepted Answer

Padding leaves gaps between adjacent sprites so scaling/sampling never picks up a neighbor. Extrude copies the sprite edge pixels outward by a few pixels, specifically to remove the dark seams that appear at sprite borders when bilinear filtering is enabled. You can use both together.

Question 5

Which engines can use the exported metadata?

Accepted Answer

The ZIP includes Unity .png.meta by default (Sprite Mode = Multiple, with slices and pivot — drop into the project to use) and a Godot 4 SpriteFrames .tres (AtlasTexture + animation clips). JSON gets a Pixi-style animations hash and meta.pivot. TexturePacker JSON (Hash/Array), Phaser 3 multiatlas, Cocos2d-x/Creator .plist, Spine / libGDX .atlas, DragonBones JSON, and CSS Sprite are also available. Use an engine preset at the top to one-click padding / extrude / POT / pivot for that engine.

Question 6

Why does it say the atlas is too large?

Accepted Answer

That only happens when a single sprite (after trim, padding and extrude) exceeds your max-size limit or the browser 16384px canvas limit. If the whole set is too big for one page, it is split across multiple pages automatically. Increase the max size or disable force-square/POT if one sprite still does not fit.

Question 7

How do I save a project so I can pack again with the same settings?

Accepted Answer

“Save project” downloads a .atlasproj.zip with every source sprite, frame names/order, and packing/engine settings. Drop that file or use “Open project” to rebuild the atlas with the same names, so gameplay references stay valid. Dropping only atlas-project.json applies settings without replacing the current sprites.

Question 8

How do I auto-build animation clips from filenames?

Accepted Answer

Name frames of the same action walk_000, walk_001 or idle-01, idle-02 (spaces and dots work too, as does heroWalk00 — a letter plus at least two trailing digits). A clip needs at least two frames. JSON includes a Pixi animations map plus meta.animations (fps / loop); Godot .tres splits clips into separate animations.

Question 9

Are identical sprites packed twice? How do folder paths become frame names?

Accepted Answer

“Dedupe identical” is on by default: bitwise-identical sprites are drawn once, while JSON / Unity / Godot still list every original name pointing at the same rectangle. Dropping or picking a folder keeps the relative path (minus the dropped root), so assets/ui/btn.png and assets/char/walk_0.png become ui/btn and char/walk_0 instead of two frames named btn. For a locked POT square, enable “Fixed atlas size” and set 2048×2048.