Will Compress Image look as small as TinyPNG?

Often closer than a canvas re-encode, still not TinyPNG. We run MozJPEG, libwebp, libavif, and oxipng in the tab. A paid cloud optimizer can still win on some files.

Does PNG compression reduce quality?

No. PNG is passed through oxipng (lossless). If the file barely shrinks, it was already well packed — pick WebP or AVIF when you can accept lossy compression.

Is there a file-size or pixel limit?

Yes. Soft caps protect the tab: 50 MB per file, 24 files in a batch, and 32 megapixels. Larger inputs are rejected rather than crashing the page.

When should I use a cloud compressor instead?

Use a cloud service when you need the smallest possible bytes for a CDN, or a specific encoder your browser cannot match. Keep StackImage for private photos, screenshots, and one-off attachments.

Can I put the compressed photos in a PDF?

Yes. After you shrink them here, assemble a packet in [StackPDF Images to PDF](https://stackpdf.stacktools.studio/images-to-pdf/) — still local, no upload.

Is Compress Image private?

Everything runs locally in your browser. Your files are never uploaded to StackImage servers.

Do I need an account to use Compress Image?

No. StackImage is free to use without signing up or creating an account.

Does Compress Image work offline?

After the page and libraries load, processing happens on your device. A connection is only needed to load the app the first time (Enhance tools also need a one-time model download).

Compress Image

Shrink JPG, PNG, WebP, and AVIF files in your browser.

How it works

1Drop one or more images into the workspace.
2Choose Light, Balanced, or Extreme and an output format.
3Compare the before/after preview and file size.
4Download the compressed file or a ZIP of the batch.

About

Compress images online without uploading them. StackImage re-encodes photos on your device so you can email, post, or archive smaller files without sending originals to a server.

Pick Light, Balanced, or Extreme, compare before and after, and download one file or a ZIP of a batch. Encoding uses MozJPEG, libwebp, libavif, and oxipng in WebAssembly — the same family of codecs as Squoosh. If the encode would be larger than the upload, we keep the original.

PNG stays lossless (oxipng). JPEG, WebP, and AVIF use quality levels (about 90 / 75 / 55). Images above 32 megapixels or 50 MB are rejected so the tab stays stable.

Common use cases

Shrink photos for email attachments
Prepare WebP or AVIF assets for a site
Batch-compress a folder of screenshots
Reduce camera originals before a chat upload

Why compress in the browser

Most “free compress image” sites upload the file, run a server encoder, and hand you a download. That is simple, and it means a copy of the photo sits on someone else’s disk — even briefly.

StackImage reads the file in your tab, re-encodes it there, and never opens an upload API. After the page loads, a flaky network does not stop the compress itself.

Quality levels and formats

Light keeps more detail. Balanced is the default for web and email. Extreme targets the smallest size and will show more artifacts on faces and text.

Stay on JPEG for photos you must hand to a system that rejects WebP. Prefer WebP or AVIF when the destination supports them — they usually beat JPEG at the same visual quality.

When not to use this tool

Do not use it as a print RIP or a RAW developer. It will not beat TinyPNG or a desktop encoder on every file, and it will refuse huge images so memory stays bounded.

Keep the original if you still need EXIF, or run Strip EXIF first. If the result is still too large for email, downscale with Resize Image, then compress again.

FAQ

Need a PDF?

Turn these photos into a private multi-page PDF in StackPDF — same no-upload model, in your browser.

Open StackPDF

Related tools

Convert Image

Convert JPG, PNG, WebP, AVIF, GIF, and HEIC locally.

Resize Image

Resize by pixels, percent, or presets like HD and Instagram.

Strip EXIF

Remove GPS, camera, and other metadata from photos.