PNG to PNG API
POST a PNG to /v2/convert/png/to/png to resize it or rewrite it without its metadata, losslessly. The sample makes a 128 px thumbnail of the 300 px sticker, transparency and all, in 21,271 bytes.
- Endpoint
- POST /v2/
convert/ png/ to/ png - Accepts
- png
- Sample timing
- 2 ms median of 5 runsHow we measure
- Request size
- Up to 10 MB on the Free plan or 100 MB on paid plans, all files together
Request and response
Every sample below ran against the API before this page was published. Set PDFCONVERSIONAPI_KEY to your key and run it as is.
curl -sS -X POST \
https://api.pdfconversionapi.com/v2/convert/png/to/png \
-H "Authorization: Bearer $PDFCONVERSIONAPI_KEY" \
-F File=@garden-plot-badge.png \
--form-string ImageWidth=128 \
-o response.json
# FileData is base64. Save the first file in converted/,
# or print the JSON error.
if jq -e '.Files' response.json > /dev/null; then
mkdir -p converted
name=$(jq -r '.Files[0].FileName' response.json)
jq -r '.Files[0].FileData' response.json \
| base64 --decode > "converted/$name"
else
cat response.json
fiimport base64
import os
import requests
key = os.environ["PDFCONVERSIONAPI_KEY"]
response = requests.post(
"https://api.pdfconversionapi.com/v2/convert/png/to/png",
headers={"Authorization": f"Bearer {key}"},
files=[("File", open("garden-plot-badge.png", "rb"))],
data={
"ImageWidth": "128",
},
timeout=180,
)
result = response.json()
if not response.ok:
raise SystemExit(f"{result['Code']}: {result['Message']}")
os.makedirs("converted", exist_ok=True)
for file in result["Files"]:
path = os.path.join("converted", file["FileName"])
with open(path, "wb") as out:
out.write(base64.b64decode(file["FileData"]))
print(path, file["FileSize"], "bytes")
import { mkdir, readFile, writeFile } from "node:fs/promises";
import { join } from "node:path";
const form = new FormData();
const file = "garden-plot-badge.png";
form.append("File", new Blob([await readFile(file)]), file);
form.append("ImageWidth", "128");
const url = "https://api.pdfconversionapi.com/v2/convert/png/to/png";
const key = process.env.PDFCONVERSIONAPI_KEY;
const response = await fetch(url, {
method: "POST",
headers: { Authorization: `Bearer ${key}` },
body: form,
});
const result = await response.json();
if (!response.ok) {
throw new Error(`${result.Code}: ${result.Message}`);
}
await mkdir("converted", { recursive: true });
for (const file of result.Files) {
const path = join("converted", file.FileName);
await writeFile(path, Buffer.from(file.FileData, "base64"));
console.log(path, file.FileSize, "bytes");
}
{
"ConversionCost": 1,
"ConversionTime": 0.002,
"Files": [
{
"FileName": "garden-plot-badge.png",
"FileExt": "png",
"FileSize": 21271,
"FileData": "iVBORw0KGgoAAAANSUhEUgAA…"
}
]
}Response from our test run on 2026-11-03. ConversionTime shows the median of 5 runs. FileData is shortened here; the real response carries the whole file as base64.
The sample, converted
The same file the code sends. Download the input and the output and compare them yourself.

- Input
- garden-plot-badge.png (39 KB)
- Output
- garden-plot-badge.png (21 KB)
- Source
- A round garden-plot sticker with a QR code, a transparent background and a soft drop shadow, drawn by us for these pages. (CC0-1.0). How it was made
- Made by
- 2026-11-04, API build
9eeeb0640aba
Parameters
Send these as form fields next to the file. Names are case-insensitive. If you set one of the documented options below that we don't support yet, the request fails with a 400 that names it instead of returning a file made without it.
| Parameter | What it does |
|---|---|
ImageWidthinteger | Width of the new PNG. 128 makes the sticker 128 × 128; 150 made it 25,701 bytes.Values: 1–20000 |
ImageHeightinteger | Height, or a box with ImageWidth: 200 × 100 gives 100 × 100 for square art.Values: 1–20000 |
ScaleProportionsboolean, default true | false distorts to fill the exact box. |
ScaleIfLargerboolean, default false | true stops small PNGs from being enlarged when you batch-process to one width. |
ScaleImageboolean, default true | false crops the top-left ImageWidth × ImageHeight instead of scaling, without any resampling. |
ImageInterpolationboolean, default false | Both values accepted; resampling always uses Lanczos3. |
ImageResolutioninteger | Writes a pHYs chunk. The input's own 144 dpi is otherwise dropped.Values: 10–800 |
ColorSpaceenum, default default | gray stores gray plus alpha (25,288 bytes for the sample); monochrome stores pure black or white plus alpha (14,034 bytes). rgb drops an alpha channel no pixel uses and turns gray into color: an opaque RGBA copy of the sticker came back as 8-bit RGB, 43,579 bytes instead of 48,546.Values: default, rgb, gray, monochrome; cmyk returns 400 |
TransparentColorstring | Pixels of exactly this color become fully transparent. #FFFFFF added 13,373 transparent pixels to the sticker's 21,347.Values: Color name, #RRGGBB or R,G,B |
FileNamestring | Output name; defaults to the upload's, garden-plot-badge.png. |
StoreFileboolean, default false | true returns a 3-hour link instead of base64. |
What carries over, and what doesn't
Kept
- Every pixel and alpha value when no resize is asked for
- 16-bit depth, for both grayscale and RGB PNGs
- Soft transparency when resizing, since alpha is resampled with the color
- The upright view of a PNG tagged with an EXIF orientation: a 300 × 200 test PNG tagged Orientation 6 came back 200 × 300, turned as the tag says
Lost or not yet supported
- Size, sometimes. Without a resize the sample grew from 40,051 to 49,783 bytes; for a smaller identical-pixel file use compress-png.
- Text chunks, the pHYs resolution (unless
ImageResolutionis set) and color profiles. - Palette storage: a palette PNG is rewritten as 8-bit RGBA, or as 8-bit RGB when it has no transparent index.
- Animation: an animated PNG becomes a still of its first frame.
Limits
- One PNG per request.
- Request bodies up to 10 MB on the Free plan or 100 MB on paid plans.
- Up to 100,000,000 pixels.
- Resize range 1 to 20,000 px.
- 120 seconds per conversion.
Where teams use it
Thumbnails of transparent art
Logos, stickers and UI icons keep their alpha and soft edges at the smaller size, so they still sit cleanly on any background.
Cleaning PNGs before publishing
Text chunks, such as an author, a description or software notes, are not written to the new file. The sample's description chunk is gone from the output.
Knocking out a flat background color
Screenshots and exported charts on a solid white or colored background can get that exact color made transparent with TransparentColor.
Questions
Why is my PNG bigger after converting?
This route rewrites the pixels with a general-purpose PNG encode, not an optimizer. The sample went from 40,051 to 49,783 bytes with identical pixels. compress-png is built for size and got the same pixels into 33,394 bytes.
Does it keep transparency when resizing?
Yes. The 128 px sample still has fully clear corners and a soft shadow.
Can I upload a JPEG to this route?
Yes. The file is identified by its content, not its name, so a JPEG saved as .png converts to a PNG (122,875 bytes for our sign photo). A file that is not an image returns 422 with "Invalid PNG signature".
What does TransparentColor do to anti-aliased edges?
Nothing. Only pixels of exactly that color are cleared; edge pixels blended toward it keep their color and opacity.
Convert your first PNG file in a minute.