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Compare Image Similarity

Compare two images and return a normalized visual similarity score.

POST /api/free/image-similarity

Use Compare Image Similarity online

Upload, configure, preview and download without an API key.

No sign-in or API key

1. Upload and settings

Use this tool online without an API key. Files are sent only when you run the request.

First image *
Second image *
Complete the required fields to run the tool.POST /api/free-online/image-similarity

2. Preview and download

Your result will appear here

Preview, size changes and download controls are shown here

Integrate with the API

Only programmatic calls require an API key. Parameters, responses and errors are documented below.

API endpoint
POST /api/free/image-similarity

Online use is keyless. Programmatic calls to this endpoint require an APIAny key.

How it works
  • Both images are normalized to the same analysis size.
  • A score of 1 means pixel-identical normalized images.

Response

A successful request returns a json response with the Content-Type described by this page.

Common errors

400
A file or parameter is missing, invalid or outside the documented limit.
401
The API key is missing, invalid or disabled for programmatic API calls.
429
The online or authenticated shared rate limit has been reached.

Parameters and limits

ParameterRequirementDefaultAccepted values
imageAFirst imageRequired—file
imageBSecond imageRequired—file

API example

Use this authenticated example in code. The online Playground above intentionally does not request or expose your key.

curl -X POST "https://apiany.ai/api/free/image-similarity" \
  -H "Authorization: Bearer $API_KEY" \
  -F "imageA=@a.png" \
  -F "imageB=@b.png"

Frequently asked questions

Do I need an API key for Compare Image Similarity?

No key is required in the online Playground. Programmatic requests use Authorization: Bearer or X-API-Key.

What are the limits for Compare Image Similarity?

Online use is limited to 3 requests per minute and 30 per day. Authenticated free accounts receive 5 RPM and paid accounts receive 500 RPM across free APIs.

Which inputs does Compare Image Similarity accept?

Use the required and optional fields in the parameter table. Unsupported formats and out-of-range values are rejected.

What does Compare Image Similarity return?

Successful requests return a json response. Errors use the HTTP status codes listed above.

Source: APIAny free API catalog and live route behavior. Content reviewed 2026-07-17.