Images are usually the heaviest thing on a blog page. A single unoptimized photo can weigh more than all the HTML, CSS, and JavaScript combined, and page speed is a Google ranking factor through Core Web Vitals. The simplest fix is to compress every image before you upload it, and you can do that in a browser for free. This post covers the 8 best online image optimizer tools in 2026, what each one does well, and the limits of their free tiers.
Updated October 2026: DIY jpg has shut down and was removed. Squoosh, ShortPixel, Kraken.io, and iLoveIMG were added. All limits and formats were rechecked in October 2026. If you would rather optimize images automatically after upload, see our guide to compressing images with the Smush plugin.
Online Image Optimizers Compared
| Tool | Formats | Free Limit | Best For |
|---|---|---|---|
| TinyPNG | PNG, JPEG, WebP, AVIF | 20 images, 5 MB each | Quick everyday compression |
| Squoosh | JPEG, PNG, WebP, AVIF, and more | No limit (runs in browser) | Full control and format conversion |
| Compressor.io | JPG, PNG, GIF, SVG, WebP | 10 MB | Lossy or lossless with sliders |
| ShortPixel Online | JPG, PNG, GIF | 10 MB per file | Lossy, Glossy, Lossless plus WebP and AVIF |
| Compressnow | JPG, PNG, GIF, WebP | Free | Choosing a compression percentage |
| Kraken.io | JPG, PNG, GIF, SVG | 1 MB per file | Small files, API users |
| iLoveIMG | JPG, PNG, GIF, SVG | Daily limits | Batch compression |
| Image Optimizer | JPG, PNG, GIF | One image at a time | Quality presets |
1. TinyPNG
TinyPNG is still my first stop. Drop up to 20 images on the page and it uses smart lossy compression to cut PNG and JPEG files by 50 to 80 percent with no visible difference, while keeping transparency. It now also compresses WebP and AVIF and can convert between JPEG, PNG, WebP, and JPEG XL. There are Photoshop and WordPress plugins (TinyPNG Compress JPEG & PNG images) that use the same engine.
Key features:
- PNG, JPEG, WebP, AVIF compression
- Converts to WebP, JXL, JPEG, PNG
- Keeps transparency
- 20 images per batch, 5 MB each
- WordPress and Photoshop plugins
Pricing: Free. Web Pro removes the batch and size limits for a yearly fee.
2. Squoosh
Squoosh is a free, open source compressor from Google that runs entirely in your browser, so nothing is uploaded and there is no file limit. You get a before and after slider, a quality control for every codec, resize and color reduction options, and output to MozJPEG, OxiPNG, WebP, AVIF, and JPEG XL. It is the tool to use when you want to see exactly what each setting does.
Key features:
- Runs in the browser, no upload
- Side by side before and after view
- WebP, AVIF, JPEG XL output
- Resize and palette reduction
- Works offline as a web app
Pricing: Free.
3. Compressor.io
Compressor.io handles JPG, PNG, GIF, SVG, and WebP, with lossy, lossless, and custom modes and a quality slider per format. The free tier accepts files up to 10 MB; a Pro plan adds larger files, bulk uploads, and resizing. It is a good middle ground between TinyPNG’s one-click approach and Squoosh’s full controls.
Key features:
- Lossy, lossless, and custom modes
- JPG, PNG, GIF, SVG, WebP
- Quality sliders per format
- Resize built in
- Free up to 10 MB
Pricing: Free. Pro plan for larger files and batches.
4. ShortPixel Online Compressor
ShortPixel is best known for its WordPress plugin, but its online tool is free and uses the same three modes: Lossy (smallest), Glossy (better quality, a bit bigger), and Lossless. You can also generate WebP and AVIF versions and download each format separately. Files up to 10 MB work without an account; signing in removes that limit.
Key features:
- Lossy, Glossy, and Lossless modes
- WebP and AVIF generation
- JPG, PNG, and animated GIF
- 10 MB per file without an account
- Same engine as the ShortPixel plugin
Pricing: Free online. Plugin plans start at a few dollars a month.
5. Compressnow
Compressnow is the simple one: choose a compression percentage, upload, download. It supports JPG, PNG, GIF, and now WebP. The ability to pick your own level is handy when you need a file under a specific size, but at high settings it will visibly degrade PNG graphics, so check the output.
Key features:
- Set the compression percentage yourself
- JPG, PNG, GIF, WebP
- Batch upload
- No account needed
- Very simple interface
Pricing: Free.
6. Kraken.io Web Interface
Kraken.io is an image optimization API used by developers, and its free web interface lets anyone compress JPG, PNG, GIF, and SVG files in lossy or lossless mode. The free limit is 1 MB per file, which is fine for screenshots and blog graphics but not for large photos. Paid plans add resizing, larger files, and cloud storage integrations.
Key features:
- Lossy and lossless modes
- JPG, PNG, GIF, SVG
- 1 MB per file on the free tier
- API and WordPress plugin available
- Download results as a ZIP
Pricing: Free web interface. Pro plans from $5 per month.
7. iLoveIMG
iLoveIMG is a suite of online image tools (resize, crop, convert, watermark) and its compressor is the fastest way to shrink a whole folder at once. Drop many files, click compress, and download a ZIP. The free tier has daily limits on files and size; the Premium plan removes them and adds batch processing without ads.
Key features:
- Batch compress many files at once
- JPG, PNG, GIF, SVG
- Part of a resize, crop, and convert toolkit
- Google Drive and Dropbox import
- Mobile apps
Pricing: Free with daily limits. Premium removes limits.
8. Image Optimizer
ImageOptimizer.net is the oldest tool on this list and still works the same way: upload one image, pick from six quality presets (best quality to minimum file size), optionally set a maximum width and height, and download. It also offers a free Windows desktop app. The results are weaker than TinyPNG or Squoosh, but the presets are useful for beginners.
Key features:
- Six quality presets
- Resize by max width and height
- JPG, PNG, GIF
- Free Windows desktop version
- One image at a time
Pricing: Free.
Which Image Optimizer Should You Use?
- Fast and no fuss: TinyPNG.
- Full control, privacy, or format conversion: Squoosh.
- WebP and AVIF versions for WordPress: ShortPixel Online or TinyPNG.
- Dozens of files at once: iLoveIMG.
Whichever tool you use, resize images to the width your theme actually displays before compressing (a 4000 pixel photo in a 800 pixel column is wasted bytes), name the file descriptively, and add alt text. Our guide to optimizing images for SEO covers the rest.
Frequently Asked Questions
Lossy or lossless: which should I choose?
Lossy for photos and screenshots on a blog; the quality loss is invisible at normal settings and the savings are far larger. Use lossless only for logos or graphics that must stay pixel perfect.
Should I convert images to WebP or AVIF?
Yes if your theme or caching plugin serves them. WebP is typically 25 to 35 percent smaller than JPEG at the same quality, and AVIF smaller still. All modern browsers support WebP, and AVIF support is now broad too.
Is an online tool better than a WordPress plugin?
Online tools are free and let you check the result before uploading. A plugin such as Smush, ShortPixel, or Imagify compresses everything automatically, including images already in your media library, which matters once a site has thousands of images. Many bloggers use both.
What size should blog images be?
Match the width of your content area, usually 800 to 1200 pixels, and aim for under 100 KB for most in-post images and under 200 KB for featured images.
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