Your plumbob keeps flickering into a llama?

1. Reads the old package. A Sims 4 loading-screen .package is a DBPF v2.1 container holding one Scaleform GFX resource. The tool opens it and pulls out that resource.
2. Lifts the bitmap. Inside the GFX there's a single DefineBitsLossless2 tag — your loading-screen image as a zlib-compressed 32-bit ARGB bitmap. The tool extracts those bytes without decoding them.
3. Puts it in a fresh GFX v15 container. The tool then pastes the bitmap bytes into the current game's loading-screen template at the next free character ID, and rewrites the placeholder DefineShape so it fills from your bitmap instead of the placeholder solid color.
4. Writes a new .package. A new DBPF v2.1 container is emitted with the same instance ID (Fix flow) or a chosen instance ID (Make flow), zlib-compressing the rebuilt GFX payload.

Nothing is uploaded. All work happens in your browser. There's no server for this tool — the page itself is a static file on GitHub Pages, and every byte of your .package stays on your machine.

Your original file is never modified. The tool reads it into memory, does the work, and offers you a new file to download. If you never click Save on the download, the fixed file goes away when the tab closes.

Your image bytes are copied byte-for-byte: we don't re-encode, recompress, or resize your bitmap. The pixel data that was in your old package is the exact pixel data in the new one — only the wrapper around it changes.

The Sims 4's loading-screen subsystem expects loading-screen packages in a specific GFX format. Old custom loading-screen mods were authored against an earlier version of that format, and the current game's renderer gets confused trying to draw them — the result is the spinning plumbob swapping frames with a llama head mid-animation.

This tool rebuilds those old packages against the current GFX template (v15), which is what the game's renderer expects today.

Some .package files don't contain a lone Scaleform GFX resource — a build-mode mod, a CAS recolor, or a script mod will fail at the first step because its contents don't match the loading-screen layout the tool expects. You'll see a specific error on the card (hover it for the full message); click Try again if you think it was transient.

The tool will also skip files larger than 50 MB. Loading screens are typically 1–10 MB; anything much bigger is almost certainly not a loading-screen package and got into the drop zone by mistake.

Sims 4 Studio can absolutely do this — it's the right tool for serious modding work. This page is the two-click version for when you already have a broken file and just want a working one: no install, no learning curve, multi-file at once, runs anywhere a browser runs (including phones and tablets).

If you're authoring new mods from scratch or need to handle anything beyond loading screens, use S4S. If you have broken loading-screen packages and want them fixed in under a minute, this is faster.

Open Advanced below and tweak the Bitmap fill scale. The default (4.7985) matches what Sims 4 Studio emits and fits a standard 16:9 image cleanly. Raise it if you see a black border around your image (the bitmap is being under-stretched). Lower it if the image is being cropped too aggressively.