PixelPrep

Compress, resize and write alt text for your images — privately, in your browser

  1. 1 Add up to 20 images
  2. 2 Press PROCESS
  3. 3 Save your files and alt text

How it works

Add your images and press PROCESS. Each one is re-encoded at quality 80 in the same format, so a JPEG stays a JPEG and a PNG keeps its transparency. If an image can't be made any smaller at its original size, you get your original file back untouched.

Click a card to fine-tune it. Drag the quality slider, type an exact width or height, or pick a size preset, then press APPLY. The comparison slider shows the original and the result side by side, so you can see what changed before you save.

While your files are being compressed, an AI model looks at each picture and writes a short description. You can edit it, copy it, or ask for a new one. Save files one by one, or press SAVE ALL to get every finished image in a single ZIP.

Privacy

Your images are never uploaded. Compression, resizing and alt text all run on your own device, inside this browser tab. Close the tab and everything you added is gone.

The only things downloaded are the tool itself and, the first time you process images, the AI model that writes alt text. That model is stored in your browser's cache so later visits start quickly. Re-encoded files are saved without EXIF data, so any GPS location your camera recorded is removed too.

Supported formats

  • JPEG — best for photos. Quality 70–85 is usually invisible to the eye.
  • PNG — screenshots, logos and anything with transparency. Instead of quality you choose how many colors to keep.
  • WebP — smaller than JPEG at the same look, with transparency support.
  • AVIF — the smallest files of all, at the cost of slower encoding.

Each image can be up to 50 MB, and you can add 20 at a time.

About alt text

Alt text is the short description screen readers speak aloud in place of an image. Search engines read it too, so it helps your pictures show up in image search. Good alt text says what matters in the picture in one plain sentence, usually under 125 characters.

You get it in two forms. With spaces goes in your page's alt attribute or your blog editor's "alt text" box. Hyphenated is the same words in lowercase joined by hyphens, and it also becomes the saved file name. The AI is a good first draft, but you know your page best, so edit freely.

FAQ

Is it free?

Yes. There is no account, no watermark and no limit on how often you use it.

Are my images uploaded?

No. All the work happens in your browser on your own device. Nothing you add is sent to a server.

Why is the first run slower?

The first time you press PROCESS, the browser downloads the AI model that writes alt text (about 230 MB, shown with a progress bar). It is cached afterwards, so later runs start in seconds. Your compressed files are ready to save while the model is still loading.

What's the hyphenated alt text for?

Descriptive file names such as red-bicycle-against-a-brick-wall.jpg help search engines understand an image. The tool names each saved file this way, and the hyphenated text is there if you want to copy it into a URL or slug field.

Which presets should I use?

Blog 1200 suits most article images. Full HD 1920 is for full-width banners, Social 1080 for Instagram and similar feeds, and Thumbnail 300 for small previews. Images are never enlarged beyond their original size.