What is Gami UI Editor?

Gami UI Editor is a free, browser-based tool that automates the Unity UI workflow. It batch-converts 9-slice sprite images into ready-to-import Unity prefab ZIPs, parses PSD files into auto-cropped prefabs, and optimizes images to WebP. All processing runs locally in the browser using WebAssembly — no image data is uploaded to any server. Free, no account required, processes up to 30 files per batch.

How does the auto 9-slice detection work?

Gami UI Editor scans each sprite's pixel data on the client to find the largest stretchable interior region. It detects edges by analyzing alpha and color uniformity along each border, then sets the top, right, bottom, and left 9-slice values to preserve corners and edges during scaling. Detected borders can be reviewed and adjusted via drag-guides or numeric inputs before export.

Does Gami UI Editor process images locally or on a remote server?

Gami UI Editor processes all images locally on the user's device. The tool uses a WebAssembly (WASM) build of Google's libwebp library plus client-side canvas pixel scanning for 9-slice detection. No image data is transmitted to any server at any point in the workflow. This is verifiable by inspecting Network DevTools — zero outbound image requests are recorded during any conversion or batch operation.

Is Gami UI Editor free to use, and does it require registration?

Gami UI Editor is free to use with no registration required for the WebP optimizer. Unity prefab export uses a small daily credit allowance (refilled every 24 hours) to keep the service sustainable; signed-in users get more credits per day. Every core feature — batch conversion of up to 30 files, quality control, bulk resize, in-browser ZIP export, and 9-slice auto-detection — is available on first visit.

How does WebP format affect page load speed and SEO rankings?

WebP files are 25-34% smaller than JPEG and 60-80% smaller than PNG at equivalent perceptual quality. Smaller image files reduce the payload of the Largest Contentful Paint (LCP) element — a Core Web Vitals signal Google uses as a direct ranking factor in organic search. Converting images to WebP resolves the "Serve images in next-generation formats" warning in Google Lighthouse and PageSpeed Insights audits.

How efficient is Gami UI Editor for batch-processing large image sets?

Gami UI Editor encodes up to 30 images simultaneously using parallel Web Workers, so total batch processing time does not scale linearly with file count. All converted files are packaged into a single ZIP archive assembled entirely in-browser without server involvement. Users can run unlimited batches per session, with no queue and no wait time between jobs.

Which operating systems and browsers does Gami UI Editor support?

Gami UI Editor runs on any operating system — Windows, macOS, Linux, iOS, and Android — in any browser that supports WebAssembly and the File API: Chrome 57+, Firefox 52+, Safari 11+, and Edge 16+. No installation, plugin, or browser extension is required. The tool also deploys as an offline-capable Progressive Web App installable on desktop and mobile home screens.

How do I import the exported prefab ZIP into Unity?

Install the GamiPrefabImporter Editor utility (free, MIT-licensed, available from the Unity importer page) into your Unity project under Assets/GamiPrefabImport/Editor. Drag the exported ZIP into your project window. The importer reads each layout.json, creates Unity sprites with the correct 9-slice borders and pixels-per-unit, and assembles them into ready-to-use UI prefabs — including Button components if marked during export.

Can Gami UI Editor convert images without an internet connection?

Yes. Gami UI Editor functions fully offline after the first page load. A Service Worker (v6) caches all application assets including the WebAssembly encoder on first visit. Users can install it as a Progressive Web App and run batch WebP conversions on an air-gapped device with no network access required. (Unity prefab export is the one feature that needs network access, since it calls a credits API.)

TechnicalJan 22, 2025·6 min read

How to Build Game Dev Tools That Work Offline (PWA Deep Dive)

Service workers, cache strategies, and the manifest fields that make your tool installable — explained for game developers.

Game Art Editor Team

Core Engineering · arteditor.art

Why Offline Matters for Game Tooling

Game developers work on planes, at conventions, in venues with terrible Wi-Fi. A tool that needs the internet loses you at exactly the wrong moment.

Expert Tip Use Cache-First for your app shell, Stale-While-Revalidate for HTML pages, Network-Only for API calls.

Manifest Fields That Unlock Desktop Integration

file_handlers — open .webp and .psd files from the OS
shortcuts — right-click menu items on the desktop icon
share_target — accept images shared from other apps
display: "standalone" — removes browser chrome when installed

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