How is this different from resizing?

Resizing stretches the pixels you have, so the image gets soft. This rebuilds detail while it adds pixels, so edges, hair and texture stay sharp.

Yes. Every AI image tool here is free to use, with or without an account, and there is no watermark. You get 10 images a day without signing in and 30 a day with a free SandBase account. The allowance resets at midnight UTC.

Are my photos stored?

No. Your photo is sent to the image model for this one request and the result comes straight back to your browser. Nothing is saved to a gallery. A copy of the result is kept in a short-lived cache for 24 hours so that pressing the button twice does not use two runs.

Does it work on my phone?

Yes. The tools work in any modern mobile browser. Tap the upload area to pick a photo or take one with the camera, then download the result to your photos.

Free · no sign-up

Free increase image resolution tool

Make an image bigger without it going soft: the AI rebuilds detail as it adds pixels, so a small file becomes a 2K or 4K image that holds up on print and big screens.

100% free
No sign-up
No watermark
Works on phone

Sample result

Example

BeforeAfter

A 320 px cabin photo rebuilt at 2K.

How to use the Increase Image Resolution

Three steps, on a computer or a phone.

1. Upload a photoDrop, paste or pick a JPG, PNG, WebP or HEIC photo. On a phone you can take one with the camera.
2. Choose your optionsSet the options, then press the button. It takes about 35 seconds.
3. Compare and downloadDrag the slider to compare with the original, then download the result.

What people use it for

PrintEnough pixels for posters, canvases and photo books.
Banners and slidesSharp images on big screens and wide layouts.
Old and small filesThumbnails and early digital photos made usable.

More free AI image tools

All free, no sign-up, no watermark.

Need more control? Use the API

This tool runs on the SandBase image API. The API gives you every setting the free tool fixes for you.

Higher quality and sizeUp to 4K output and any aspect ratio, including extra-wide and tall.
Your own promptChange the template below, add reference images, or batch hundreds of images from your code or Agent.
No daily limitPay per image from one SandBase balance, with the same key for 2,000+ models and APIs.

API reference Image models and prices Get an API key

curl https://api.sandbase.ai/v1beta/models/google/gemini-nano-banana-2.1:generateContent \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"contents":[{"role":"user","parts":[
        {"text":"Increase the resolution of this image and rebuild fine detail: sharp natural detail, no blur or noise. Keep the content,…"},
        {"inline_data":{"mime_type":"image/jpeg","data":"<base64 photo>"}}]}],
       "generationConfig":{"responseModalities":["IMAGE"],"imageConfig":{"imageSize":"4K"}}}'

The free tool uses this prompt template with your choices filled in.

Frequently asked questions

How is this different from resizing?: Resizing stretches the pixels you have, so the image gets soft. This rebuilds detail while it adds pixels, so edges, hair and texture stay sharp.
Is it really free?: Yes. Every AI image tool here is free to use, with or without an account, and there is no watermark. You get 10 images a day without signing in and 30 a day with a free SandBase account. The allowance resets at midnight UTC.
Are my photos stored?: No. Your photo is sent to the image model for this one request and the result comes straight back to your browser. Nothing is saved to a gallery. A copy of the result is kept in a short-lived cache for 24 hours so that pressing the button twice does not use two runs.
Does it work on my phone?: Yes. The tools work in any modern mobile browser. Tap the upload area to pick a photo or take one with the camera, then download the result to your photos.