Resize, crop, compress and convert with 1 API call

Integrate image editing into your app or workflow. POST an image with the dimensions, crop, format and file-size budget you want — get the optimized bytes straight back. Pure CPU processing, no queue, no cold starts.

Not a developer? Use the web app instead — no code required.

Easy to integrate

A simple HTTP interface with sensible options:

Source images

Direct upload (image_file), a URL (image_url), or a base64 string (image_base64). JPG, PNG, WebP, GIF, TIFF and AVIF in — up to 50 MB and 64 megapixels.

Result images

Binary image file by default, or JSON-encoded data (base64 + dimensions) with Accept: application/json.

Output resolution

Any size up to 8000×8000 px, full resolution, never watermarked.

Get started

Create an API key in your dashboard, then send your first request. Optimization calls are free by default; failed calls are never charged. Authenticate with X-Api-Key: rs_live_… (or Authorization: Bearer rs_live_…).

Sample code

Resize to 1200px wide, convert to WebP and stay under 200 KB:

curl -H "X-Api-Key: rs_live_..." \
  -F "image_file=@/path/to/photo.jpg" \
  -F "width=1200" \
  -F "format=webp" \
  -F "target_kb=200" \
  -f https://usely.tools/api/v1/resize \
  -o photo-1200.webp

Cut an exact region with a smart crop:

# Smart-crop a 1080×1080 square around the most interesting region,
# then resize is skipped (crop output IS the result)
curl -H "X-Api-Key: rs_live_..." \
  -F "image_file=@banner.jpg" \
  -F "crop_width=1080" -F "crop_height=1080" \
  -F "gravity=attention" \
  -f https://usely.tools/api/v1/resize -o square.jpg

Output formats

Request one of the formats below via the format parameter, or omit it (keep) to stay in the input format.

For photos on the web, webp with a target_kb budget is the sweet spot. Use png when you need pixel-perfect graphics or lossless transparency.

API Reference

POST /api/v1/resize

Resizes, crops, compresses and/or converts a JPG / PNG / WebP / GIF / TIFF / AVIF image. File size up to 50 MB; input up to 64 megapixels; output up to 8000 px per side. Requires an API key in the X-Api-Key header (or a Bearer token in Authorization). All parameters are optional — with none, the call is a pure re-encode.

Request body — multipart/form-data or application/json

Request headers

Responses

Response headers

Account endpoint

GET /api/v1/account

Fetch the current credit balance for the authenticated key. Balance changes may lag a few seconds; to track locally, read this once and then adjust using the X-Credits-Charged header returned by each call.

{
  "data": {
    "credits": { "balance": 200 }
  }
}