Free Online Image Compressor
Reduce image file size while maintaining quality. Adjustable compression level and batch support. Selected image contents are processed locally in your browser.
Drag and drop files here
or
Accepted input: JPG, PNG, or WebP
How to Compress Images
- Choose one or more images (JPG, PNG, WebP)
- Pick what the file is for — the settings follow your choice
- Compare the three results and their real file sizes, or open Fine-tune to set quality and maximum width yourself
- Download files individually or once as a ZIP
Features
- Purpose presets, with three finished results to compare
- Adjustable quality from 10% to 100% under Fine-tune
- Verified exact-size mode with an honest target status
- Optional starting max width
- Batch compress with one ZIP download
- Shows before/after file sizes
- Selected image contents are processed locally in your browser
- Capacity depends on browser memory and Canvas limits
Practical limits
Browser processing safeguards
These are ToolkitFree screening thresholds, not promises that every browser can reach them.
| Safeguard | Desktop | Mobile |
|---|---|---|
| Single-image hard cap | 100 MP | 100 MP; the 80 MP total cap can block first |
| Batch size warning | 20 files | 10 files |
| Batch size block | 50 files | 25 files |
| Encoded input warning | 100 MiB | 40 MiB |
| Encoded input block | 250 MiB | 100 MiB |
| Total pixels warning | 80 MP | 32 MP |
| Total pixels block | 200 MP | 80 MP |
| Working memory warning | 512 MiB | 192 MiB |
| Working memory block | 1 GiB | 384 MiB |
| Parallel processing | Up to 2 images | Up to 2 images |
Large dimensions can exhaust browser memory before encoded file size looks large. ToolkitFree checks dimensions and estimated working memory before processing.
Frequently Asked Questions
How does image compression work?
Our compressor re-encodes your image using the browser's Canvas API. For JPEG images, it adjusts the compression level; for PNG, it uses PNG encoding. The selected image contents are not sent to ToolkitFree for compression.
What's the difference between quality levels?
Visible quality and file-size reduction vary with the source image, dimensions, format, and selected quality. Compare the displayed result before downloading; lower quality settings can introduce visible artifacts.
Can I compress PNG images?
Yes, but PNG is a lossless format, so quality adjustment has no effect on PNG. You can reduce PNG file size by limiting the maximum width, which scales down the image dimensions.
How much can I reduce file size?
There is no guaranteed percentage. Results depend on image content, dimensions, original encoding, output format, and the selected quality setting.
Is there a batch compression limit?
There is no server-side batch quota, but the practical limit depends on available browser memory and image dimensions. Large batches can be slow or fail, especially on mobile devices.
Can I download all compressed images at once?
Yes. After processing, Download all as ZIP creates one local archive containing only successful results. Individual downloads remain available, and any failed file stays visible with its error reason.
Will compression affect image dimensions?
No, unless you set a Max Width limit. By default, compression only affects file quality, not dimensions. If you set a Max Width, images wider than that limit will be scaled down proportionally.
How do I make a photo smaller to email?
Choose your photo, try a lower quality or maximum width, and compare the displayed output size with your email provider's attachment limit. A specific output size is not guaranteed.
How do I reduce image file size to under 100KB?
Choose the "Exact size in KB" purpose and enter 100. The tool uses bounded quality and dimension search, then labels each result Target met only when its actual Blob is 100KB or less.
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