How do I compress an image online for free?

Drop your photo into the uploader, slide the quality control while watching the live before/after preview, and click download. ImgShifter compresses JPG, PNG, WEBP, and AVIF images directly in your browser using the same encoders (MozJPEG, libwebp, AVIF, and Oxipng) that production image pipelines use. There's no signup, no watermark, no file-size paywall, and no upload to a server - the image is processed on your device and the file you download is the only copy that leaves the page.

Which image formats can I compress?

JPG, JPEG, PNG, WEBP, and AVIF are all supported in the browser compressor. JPG, WEBP, and AVIF output use lossy compression, where the quality slider trades visual detail for smaller files. PNG output is lossless - Oxipng re-compresses the file without changing a single pixel, so the quality slider doesn't apply and transparency is kept. The output defaults to your file's own format; switch it to WEBP or AVIF for the smallest files, keeping transparency, or to JPG for maximum compatibility.

How much can I reduce my image's file size?

It depends on the source. A JPG straight from a phone camera typically shrinks 60-80 percent at quality 75-80 without any visible difference. A PNG typically shrinks 5-40 percent losslessly (on ten PNGs we tested, savings ranged from 7 to 41 percent), and far more if you re-encode it as WEBP or AVIF. An uncompressed PNG photo can shrink by more than 90 percent if you accept JPG or WEBP output. The before/after preview and live file-size readout let you find the lowest setting that still looks acceptable for your use case.

How do I compress a JPG, PNG, or WEBP without losing quality?

For PNG, use the lossless PNG output - Oxipng re-encodes the file with stronger compression so it shrinks without any pixel-level change. If the PNG is already optimal, you get the original back unchanged. For JPG and WEBP, quality 80-90 is usually visually indistinguishable from the original; below 70, artifacts start showing in flat areas and around sharp edges. Avoid compressing the same JPG repeatedly - every pass compounds artifacts. Start from the highest-quality source you have.

Can I compress an image to a specific size like 100KB, 500KB, or 1MB?

Yes. ImgShifter has dedicated pages for the most common target sizes - 50KB, 100KB, 250KB, 300KB, 500KB, and 1MB - that use a binary-search algorithm to find the highest quality setting that still meets the size limit. These are handy for upload forms with strict file-size limits (passport photos, government applications, school portals, job sites, e-commerce listings, email attachments). Use the main compress tool if you want manual control over the quality slider instead.

Is it safe to compress images online? Are my files uploaded?

No upload happens for the browser compressor. JPG, PNG, WEBP, and AVIF compression runs entirely on your device using WebAssembly encoders, so your image never reaches an ImgShifter server, never appears in a log, and never gets cached on a CDN. You can verify this two ways: open the browser's Network tab while you compress (no outbound image traffic) or disconnect from the internet after the page loads (the tool keeps working). This makes ImgShifter a safe choice for sensitive content like ID photos, medical images, business documents, or anything you'd rather not hand to a third-party server.

Which format gives the smallest file size - JPG, WEBP, or AVIF?

AVIF is usually the smallest, often 30-50 percent smaller than JPG at the same visual quality and 20-30 percent smaller than WEBP. WEBP is the safe modern default - 25-35 percent smaller than JPG, supported in every modern browser, and faster to encode than AVIF. JPG is the most compatible and the right choice for email attachments, older CMSes, or anywhere unknown software will open the file. If you're shipping images to a modern website, convert to WEBP or AVIF first, then compress.

Why is my compressed image still large?

A few common causes. First, you're starting from a PNG photograph - PNG is lossless and can't shrink as much as JPG or WEBP without changing format. Convert to JPG or WEBP first, then compress. Second, the quality slider is set too high - try 70-80 for photos. Third, the image's actual pixel dimensions are very large (say 6000 x 4000 from a DSLR) - resize first using the Resize Image tool, then compress. Compression reduces detail-per-pixel; resizing reduces total pixels. Combine both for the biggest savings.

Does compressing an image change its dimensions?

No. Compression changes file size by re-encoding the image at a lower bitrate or with a stronger compressor - the pixel width and height stay the same. If you also need a smaller resolution (for a thumbnail, profile picture, or to fit a specific layout), use the Resize Image tool first to shrink the dimensions, then compress for the final file-size reduction.

Can I compress images on my phone?

Yes. The compressor runs in the mobile browser - drop a photo from your camera roll, slide the quality control, and download the smaller file straight back to your device. iPhone HEIC photos are accepted on the conversion tools first (use HEIC to JPG or HEIC to PNG, then compress) since the compressor expects a standard format. Modern Android, iPhone, and iPad browsers all work.

Browser only - 100% private

Compress Image

Reduce image file size with a quality slider and instant before/after stats. Powered by the jsquash MozJPEG, libwebp, AVIF, and Oxipng encoders.

Before/after preview
Privacy-first
No signup

Drag, drop, paste, or browse

JPG, PNG, WEBP, GIF, and AVIF up to 50 MB. Paste from clipboard with Ctrl+V.

Batch upload supported

Settings

Tune output without leaving the browser.

Target size

Quality78%

SmallerSharper

Output format

Best compatibility, great for photos. Transparent areas become white.

OriginalNo file

ProcessedWaiting

Reduction-

ProcessingBrowser

Before / after preview

Compare the source image with the generated file.

OriginalWaiting

Upload an image to begin

ProcessedWaiting

Run a tool to preview output

Result download

Your processed image will appear here.

Waiting for a result

Guide

Useful to know

Quality vs file size

Lower quality settings shrink files but introduce artifacts in flat areas like skies and skin. For most photos, 70-85% quality is visually indistinguishable from the original at typical viewing sizes.

What gets compressed

ImgShifter compresses JPG, PNG, WEBP, and AVIF locally in your browser. PNG output is lossless (Oxipng), and the output defaults to your file's own format. JPG, WEBP, and AVIF are lossy, so re-compressing the same file repeatedly compounds quality loss.

Compress online with ImgShifter

ImgShifter compresses images locally with WebAssembly builds of MozJPEG, libwebp, and libavif from the jsquash project, plus Oxipng for lossless PNG. The slider controls quality directly, and the before/after preview gives an instant read on visual loss before you commit to a download.

PNG output is lossless. JPG, WEBP, and AVIF are lossy, so re-compressing the same file repeatedly compounds artifacts - start from the highest-quality source you have. Files of up to 50 MB process comfortably; larger files are limited only by your device's available memory.

Every byte stays on your device. You can verify by opening the Network tab while you compress, or by disabling your network after the page loads - the tool keeps working.

Keep going

Other ImgShifter tools people use alongside Compress.

Compress to 1 MB

Automatically compress any image to under 1 MB using jsquash binary-search encoding.

Open tool

Compress to 500 KB

Automatically compress any image to under 500 KB using jsquash binary-search encoding.

Open tool

Compress to 100 KB

Automatically compress any image to under 100 KB using jsquash binary-search encoding.

Open tool

Resize

Resize photos and graphics with aspect-ratio presets and bulk support, right in your browser.

Open tool

Read

Deeper guides related to Compress from the ImgShifter blog.

Image Too Large to Upload? How to Fix It on Any Device (2026)

Phone photos run 3 to 6MB and plenty of upload forms stop at 2MB. How to shrink, convert or resize an image so it uploads, on any phone or computer.

Read the guide

WebP vs. JPEG vs. PNG vs. AVIF: Which Image Format Should You Actually Use?

JPEG, PNG, WebP, and AVIF compared in plain English — what each format does well, what it breaks on, where browser support stands in 2026, and which one to actually ship for photos, graphics, and the web.

Read the guide

FAQ

Frequently asked questions

Short answers for image workflows, privacy, and supported formats.

Compress Image

Drag, drop, paste, or browse

Settings

Before / after preview

Result download

Useful to know

Quality vs file size

What gets compressed

Compress online with ImgShifter

Related tools

Compress to 1 MB

Compress to 500 KB

Compress to 100 KB

Resize

From the blog

Frequently asked questions

How do I compress an image online for free?

Which image formats can I compress?

How much can I reduce my image's file size?

How do I compress a JPG, PNG, or WEBP without losing quality?

Can I compress an image to a specific size like 100KB, 500KB, or 1MB?

Is it safe to compress images online? Are my files uploaded?

Which format gives the smallest file size - JPG, WEBP, or AVIF?

Why is my compressed image still large?

Does compressing an image change its dimensions?

Can I compress images on my phone?