BlurHash as a service

Image in.28 characters out.

The backdrop above is not a photograph. It is the string below, decoded by this API's /decode endpoint — small enough to sit in a database column next to the image URL, and to arrive with your JSON instead of after it.

LEHV6nWB2yk8pyo0adR*.7kCMdnj

1 char · grid: 4 × 3 components
1 char · contrast: scale of the detail terms
4 chars · base colour: the image's average
22 chars · detail: 11 cosine terms, 2 chars each

Try it

Runs against this API, in your browser.

components x y

Result Your image and its hash, side by side,
with the timings the server measured.

The BlurHash, decoded back into a placeholder — The hash, decoded

Endpoints

No key, no signup. CORS is open.

POST /blurhash

Send the image as the raw request body. This is the fastest path — nothing to parse before the decoder sees the bytes.

# the response is JSON on stdout
curl -X POST --data-binary @photo.jpg https://blurhash.wrapuj.to/blurhash

POST /blurhash multipart

Or post a form. The file field may be named image, file or upload.

curl -F [email protected] https://blurhash.wrapuj.to/blurhash

GET /blurhash?url=

Hand over a URL and the API fetches the image itself. Results are cached for an hour, so a repeat call answers from memory. Only public addresses are reachable.

curl 'https://blurhash.wrapuj.to/blurhash?url=https://example.com/photo.jpg'

GET /decode?hash=

The inverse: a hash back into a PNG placeholder, for previews and debugging. width, height and punch are optional.

curl 'https://blurhash.wrapuj.to/decode?hash=LEHV6nWB2yk8pyo0adR*.7kCMdnj&width=320' > blur.png

Response

Every hashing call answers with the same shape. width and height describe the original image, so you can set the placeholder's aspect ratio without a second request.

{
  "blurhash": "LEHV6nWB2yk8pyo0adR*.7kCMdnj",
  "width": 4032,
  "height": 3024,
  "components": { "x": 4, "y": 3 },
  "format": "jpeg",
  "bytes": 2847193,
  "sampled": { "width": 100, "height": 75 },
  "timing_ms": { "decode": 3.1, "encode": 0.4 }
}

Errors

Failures come back as JSON with a stable code and a message meant to be read by a person.

{ "error": { "code": "unsupported_format",
            "message": "GIF is not supported; send JPEG, PNG or WebP" } }

What it does

And what it deliberately does not.

Formats: JPEG, PNG, WebP. The container is read from magic bytes, not from the Content-Type you send.
Speed: JPEGs are decoded through the DCT scaler, so a 12 MP photo never reaches full resolution in memory.
Components: 1–9 on each axis via x and y. Defaults to 4 × 3, the size the reference recommends.
Transparency: Alpha is dropped, not composited — matching the reference encoders. A hash cannot carry transparency.
Upload limit: 25 MB per image, and at most 80 megapixels before scaling.
Compatibility: Output is byte-identical to woltapp/blurhash, so any client decoder reads it.