The best compression of any mainstream image format, running as WebAssembly in your own tab. Drop a PNG, let the encoder work, and download a file that's often a seventh of the size.
Add one or many — PNG, JPG & WebP. Or paste with ⌘/Ctrl + V
Open this page from the served app, drop your PNG, and AVIF is already selected for export — the toast confirms it. Click Export: PixKit loads the @jsquash WASM encoder on first use, encodes on your device, and downloads the AVIF. Only the codec is fetched; your image pixels never leave your machine.
Clean the Gemini sparkle, then finish the job — crop, resize, convert and adjust without uploading a single pixel.
Reverse-alpha math restores the true pixels under the Gemini logo — no blur, no AI guesswork.
Crop to any aspect ratio with draggable handles, then resize to exact pixels or quick scales.
Export to PNG, JPG or WebP with a quality slider and a live file-size estimate.
Every tool runs locally with undo/redo. Nothing is uploaded — it even works offline.
One extra beat for the encoder — then the smallest files on the web.
AVIF encoding needs the app running over http — if you opened the file directly, the export card will say "AVIF needs the served app (run start.command)". On pixkit.com or localhost, just drop your image.
The toast reads "Ready — click Export to download as AVIF." The first export fetches the @jsquash WASM codec (a one-time download of the encoder, not your image), then encodes locally. Give it a moment — AVIF works harder per pixel than JPG or WebP, and the size estimate shows the payoff.
Often around a seventh of the PNG's size, transparency included. Batch several PNGs into one ZIP, or use the target-KB field for an exact byte budget.
When performance budgets are brutal, AVIF beats WebP and demolishes JPG/PNG — the same hero photo at a fraction of even WebP's size.
Galleries, catalogs and CDN-billed sites multiply every saved kilobyte by every visitor. AVIF's ~7×-over-PNG savings compound fast.
AVIF supports alpha, so cut-out product shots and illustrations keep their transparency while dropping most of their weight.
Internal dashboards, web apps and PWAs that only target current browsers can go all-in on AVIF with zero fallback plumbing.
Convert a few of your real assets locally and compare sizes and looks before committing your build pipeline to a new format.
AVIF questions, answered before you hit Export.
AVIF is the current end of the image-compression road. Built on the AV1 video codec, it out-compresses everything mainstream — JPG, PNG and WebP alike — and the gap over PNG is startling: photographic PNGs routinely come out around seven times smaller as AVIF at visually equivalent quality, and even graphics see savings WebP can't reach. It supports full alpha transparency, wide color gamuts and HDR, and every modern browser — Chrome, Firefox, Safari, Edge — displays it natively. If your images only need to live on the modern web, AVIF is the smallest they can be.
First, encoding speed: AVIF spends far more CPU per pixel than JPG or WebP in exchange for those file sizes, so a large PNG takes seconds rather than an instant blink — the export card notes when encoding is underway, and batches simply take proportionally longer. Second, reach: browsers are covered, but plenty of desktop software and older upload forms still can't open .avif. Treat AVIF as a delivery format for the web, keep PNG masters, and use the reverse converter whenever some tool refuses the file.
Browsers can all decode AVIF, but most can't encode it natively, so PixKit ships the encoder to you instead: on your first AVIF export it loads the @jsquash codec — a WebAssembly build of the reference AV1 encoder — from a CDN, then runs it inside your tab. That's why this tool needs the app served over http (pixkit.com, or start.command locally): browsers block module loading from file:// pages. To be clear about what travels where — the one-time download is the codec itself; your image pixels are encoded on your machine and are never uploaded anywhere.
The export card gives you AVIF's quality slider with a live size estimate, plus the compress-to-target-KB mode when you need each file under an exact budget. Drop multiple PNGs and export the accepted set as a ZIP — the encoder works through them sequentially on your CPU with no usage credits. It's a practical way to convert a real asset set and see what AVIF would save before you rewire a build pipeline around it. Keep the PNG originals as masters — AVIF is the copy you ship to browsers, not the copy you archive for the long term.
| PixKit | Typical online tools | |
|---|---|---|
| Where your image is processed | On your device — nothing is uploaded | Uploaded to the tool's servers |
| Price, accounts & limits | No sign-up or usage credits; browser safety limits apply | Free-tier caps, accounts, paywalls |
| Speed on large files | No upload or queue; speed depends on the device | Upload, wait in queue, download |
| Works offline | Yes — installs as a PWA | No connection, no tool |
| Where the AVIF encoder runs | WASM in your tab — pixels stay local | Your images encode on their servers |
| Encoding cost & limits | No usage credits; your CPU does the work within browser safety limits | Slow queues, daily caps, premium AVIF tiers |
| Transparency in AVIF output | Alpha preserved automatically | Varies — some flatten silently |
One private editor, a tool for every job — all 100% local, no upload.