What is SpritePacker?
SpritePacker is a free, browser-based sprite sheet packer and converter built for 2D game developers who need engine-ready texture atlases without friction. It takes individual PNG or JPG frames, packs them into a tight atlas using MaxRects bin-packing, and exports the result as PNG alongside JSON, XML, CSS, or SCSS coordinate data. Everything runs locally in your browser tab — no account, no server upload, no waiting. You can also extract frames from a packed sheet, split GIFs into numbered frame grids, or turn an atlas back into an animated GIF, all from the same tool.
Who it's for
- Indie game developers who need a fast, reliable way to assemble animation frames and UI states into a single atlas before dropping them into Unity, Godot, Phaser, or GameMaker.
- Web and mobile creators working with PixiJS, Phaser, or CSS-based animations who want coordinate data in the exact format their renderer expects, without manual conversion.
- Privacy-conscious teams who handle unreleased or sensitive artwork and need a packing tool that never sends image files to a server — everything stays on the local device.
Key features
MaxRects bin-packing
SpritePacker uses genuine MaxRects packing rather than a simple grid layout. This produces smaller atlases and fewer draw calls, which matters when you're shipping for performance-constrained platforms.
Animation diagnostics
Before you export, deterministic quality checks flag duplicate frames, subject drift, edge bleed, palette shifts, and loop jumps. These diagnostics help you catch visual glitches that would otherwise only appear at runtime.
Playback studio
Preview your animation with per-frame hold times, onion skinning, loop, and speed controls. The timing you see in the preview is exactly what gets exported, so there are no surprises between design and implementation.
Multi-format export
Download a packed PNG plus a GIF with preserved per-frame timing, Phaser 3/PixiJS atlas JSON, TexturePacker Generic XML for Unity, CSS/SCSS, and a rich metadata JSON. Engine presets for Unity, Godot, Phaser, PixiJS, and GameMaker give you one-click defaults tuned for each pipeline.
What stands out
Your art never leaves your machine — packing, trimming, and export all happen locally in your browser.
That privacy guarantee is the core differentiator. Most sprite sheet tools require uploading frames to a remote server, which is a non-starter for teams with unreleased projects or strict data policies. SpritePacker decodes, packs, and renders everything inside Canvas and Web Workers in your tab, so files stay on your device. It also includes practical extras like auto-trim with offset preservation, edge extrusion to prevent texture bleeding, and scale/alignment controls from 1–8× with nearest-neighbour scaling — features that usually live in paid desktop tools.
Worth checking out if…
You're a 2D game developer who wants a free, no-sign-up sprite sheet packer that produces genuinely tight atlases with engine-ready export data. It's especially useful if you work with Unity, Godot, Phaser, PixiJS, or GameMaker and want to avoid manual coordinate mapping. If you handle sensitive or unreleased artwork, the local-only processing model is a strong reason to try it. And if you regularly convert between sprite sheets and GIFs or need to slice an existing atlas back into individual frames, the bundled converters make this a complete pipeline tool rather than just a packer.
