Advanced delivery options

Change filename

Your original filenames can be accessed via REST API. Make a request to receive a JSON response with file parameters including original_filename.

You can set an optional filename that users will see instead of the original name:

https://ucarecdn.com/:uuid/:filename

:filename should comply with file name conventions and it should be a valid part of a URL. For example, filename.ext.

Get file info as JSON

-/json/

Returns file-related information, such as image dimensions or geotagging data in the JSON format.

/:uuid/-/json/
/:uuid/-/preview/-/json/

In the second option, json response will contain the original key with the info on your original image.

Get file info as application/javascript

-/jsonp/

Same as the example above, but it returns data as the application/javascript type. The callback name should always be uploadcare_callback. It should receive the two following arguments: id and a response object. For original files, id is equivalent to their UUIDs. For processed files, id is equivalent to their URLs, excluding the last operation, jsonp.

/:uuid/-/jsonp/
/:uuid/-/preview/-/jsonp/

In the first case id will be c5b7dd84-c0e2-48ff-babc-d23939f2c6b4, in the second: /c5b7dd84-c0e2-48ff-babc-d23939f2c6b4/-/preview/.

Perceptual hash

File info response includes a value of a perceptual hash calculated using pixel contents of an image. Perceptual hashing is a common fingerprinting technique to quickly compare images and find duplicates or similar images.

Uploadcare automatically calculates a 64-bit long perceptual hash value and returns it as a HEX string. In this example, the perceptual hash value is 940f5fd09aa48ddc:

{
  "id": "1b192edb-212d-401a-ad9b-529047272e1b",
  "datetime_original":null,
  "orientation":null,
  "height":1600,
  "width":2400,
  "geo_location":null,
  "format":"JPEG",
  "hash":"940f5fd09aa48ddc"
}

It’s easy to find image duplicates by quickly comparing their perceptual hash values. To find similar images, it's important to compare perceptual hash values bitwise (Hamming distance). A small number of unmatched bits (e.g., up to 8 bits) will correspond to subtle changes in the visual contents, while non-similar images will usually have more than 8 different bits.

Show or download

-/inline/yes/ -/inline/no/

By default, CDN instructs browsers to show images and download other file types. The inline control allows you to change this behavior.

/:uuid/-/preview/-/inline/no/
/:uuid/-/inline/yes/

Accessing single files in a group

Request a specific file in a group by adding /nth/i/, where i is a file index, starting from 0:

/:group_uuid/nth/0/
/:group_uuid/nth/1/
/:group_uuid/nth/2/

Note, there is no /-/ separator after a group UUID. It's required for transformations only.

By the way, you can apply Image Transformations to indivitual files within a group:

/:group_uuid/nth/0/-/resize/256x/

You can also group the processed files with the respective operation sequences. When you request a file by its group URL, it'll include all operations before adding it to that group. Adding more operations after /-/ will apply them over the existing ones.

Get a group as an archive

Getting a group as an archive is done via the archive group processing operation.

The operation limits are:

• A total size of uncompressed files ≤ 2 GB.
• Processing operations will be discarded. Only original files will be archived.

Here's how to get an archived file group:

/:group_uuid/archive/:format/:filename

• :group_uuid — UUID of a file group you want to get as an archive.
• :format — the format of that output archive, we support zip and tar.
• :filename (optional) — output archive filename.

Note: If the group contains a removed file, the archive operation will fail with a 404 error code.