# Add an image watermark to a PDF Stamp a PNG or JPEG image across the pages of a PDF, with control over transparency, margin, and which pages get it. Add an image watermark to a PDF document. Supply a PNG or JPEG and control its transparency and margin. By default the watermark is stamped on every page: use the [`pages`](#selecting-pages) parameter to target a subset. The API is stateless: your document is processed in-region and never stored. ## Endpoint <Endpoint method="POST" path="/v1/add_image_watermark" /> Available in every region. See [Regions & data residency](/docs/api/regions-and-data-residency) for routing and data residency. | Region | URL | | -------------- | --------------------------------------------------- | | Global | `https://api.pdfblocks.com/v1/add_image_watermark` | | United States | `https://us.api.pdfblocks.com/v1/add_image_watermark` | | US HIPAA | `https://hipaa.api.pdfblocks.com/v1/add_image_watermark` | | European Union | `https://eu.api.pdfblocks.com/v1/add_image_watermark` | | United Kingdom | `https://uk.api.pdfblocks.com/v1/add_image_watermark` | | Canada | `https://ca.api.pdfblocks.com/v1/add_image_watermark` | | Australia | `https://au.api.pdfblocks.com/v1/add_image_watermark` | | Japan | `https://jp.api.pdfblocks.com/v1/add_image_watermark` | | India | `https://in.api.pdfblocks.com/v1/add_image_watermark` | | Brazil | `https://br.api.pdfblocks.com/v1/add_image_watermark` | ## Authentication Authenticate every request with your secret API key in the `X-API-Key` header, over HTTPS. Create and manage keys from the [dashboard](https://dashboard.pdfblocks.com). See [Authentication](/docs/api/authentication) for details. ## Request The endpoint accepts a `multipart/form-data` request body. <ParamField name="file" type="file" required> The input PDF document. </ParamField> <ParamField name="image" type="file" required> The watermark image to stamp onto each page. Must be a PNG or JPEG. See [Working with files](/docs/api/working-with-files) for how to attach it. </ParamField> <ParamField name="transparency" type="integer" default="50"> The transparency level, from `0` (fully opaque) to `100` (fully transparent). </ParamField> <ParamField name="margin" type="decimal" default="1.0"> The distance, in inches, from the page border to the watermark. `0` or greater. </ParamField> <ParamField name="pages" type="string"> The pages to stamp, written as a [page range](#selecting-pages) such as `1..3,5`. When omitted, the watermark is applied to every page. Maximum 1000 characters. </ParamField> ### Selecting pages The `pages` parameter takes a comma-separated list of 1-based page numbers and ranges. It is treated as a **set**: order and duplicates are ignored, and pages are always stamped in document order. | Pattern | Selects | | --------- | ------------------------------------------ | | *(omit)* | Every page | | `1` | The first page only | | `1..3,5` | Pages 1, 2, 3, and 5 | | `2..` | Page 2 through the last page | | `..-2` | The first page through the second-to-last | | `-1` | The last page | See [Selecting pages](/docs/api/selecting-pages) for the complete reference. ## Examples Stamp a logo on every page at 60% transparency: <CodeGroup> ```bash title="cURL" curl https://api.pdfblocks.com/v1/add_image_watermark \ -H 'X-API-Key: your_api_key' \ -F file=@input.pdf \ -F image=@logo.png \ -F transparency=60 \ -o watermarked.pdf ``` ```python title="Python" # pip install requests import requests with open('input.pdf', 'rb') as file, open('logo.png', 'rb') as image: response = requests.post( 'https://api.pdfblocks.com/v1/add_image_watermark', headers={'X-API-Key': 'your_api_key'}, files={'file': file, 'image': image}, data={'transparency': 60}, ) response.raise_for_status() with open('watermarked.pdf', 'wb') as output: output.write(response.content) ``` ```javascript title="Node.js" // Node.js 18+ import { readFile, writeFile } from 'node:fs/promises'; const body = new FormData(); body.set('file', new Blob([await readFile('input.pdf')]), 'input.pdf'); body.set('image', new Blob([await readFile('logo.png')]), 'logo.png'); body.set('transparency', '60'); const response = await fetch('https://api.pdfblocks.com/v1/add_image_watermark', { method: 'POST', headers: { 'X-API-Key': 'your_api_key' }, body, }); if (!response.ok) throw new Error(`Request failed: ${response.status}`); await writeFile('watermarked.pdf', Buffer.from(await response.arrayBuffer())); ``` ```php title="PHP" <?php $ch = curl_init('https://api.pdfblocks.com/v1/add_image_watermark'); curl_setopt_array($ch, [ CURLOPT_RETURNTRANSFER => true, CURLOPT_HTTPHEADER => ['X-API-Key: your_api_key'], CURLOPT_POST => true, CURLOPT_POSTFIELDS => [ 'file' => new CURLFile('input.pdf', 'application/pdf'), 'image' => new CURLFile('logo.png', 'image/png'), 'transparency' => '60', ], ]); $pdf = curl_exec($ch); if (curl_getinfo($ch, CURLINFO_HTTP_CODE) === 200) { file_put_contents('watermarked.pdf', $pdf); } ``` ```ruby title="Ruby" # gem install http require 'http' response = HTTP .headers('X-API-Key' => 'your_api_key') .post('https://api.pdfblocks.com/v1/add_image_watermark', form: { file: HTTP::FormData::File.new('input.pdf'), image: HTTP::FormData::File.new('logo.png'), transparency: '60', }) File.write('watermarked.pdf', response.body) if response.status.success? ``` ```go title="Go" package main import ( "bytes" "io" "mime/multipart" "net/http" "os" ) func main() { var buf bytes.Buffer form := multipart.NewWriter(&buf) file, _ := os.Open("input.pdf") defer file.Close() filePart, _ := form.CreateFormFile("file", "input.pdf") io.Copy(filePart, file) image, _ := os.Open("logo.png") defer image.Close() imagePart, _ := form.CreateFormFile("image", "logo.png") io.Copy(imagePart, image) form.WriteField("transparency", "60") form.Close() req, _ := http.NewRequest("POST", "https://api.pdfblocks.com/v1/add_image_watermark", &buf) req.Header.Set("Content-Type", form.FormDataContentType()) req.Header.Set("X-API-Key", "your_api_key") res, _ := http.DefaultClient.Do(req) defer res.Body.Close() out, _ := os.Create("watermarked.pdf") defer out.Close() io.Copy(out, res.Body) } ``` ```csharp title="C#" using var client = new HttpClient(); client.DefaultRequestHeaders.Add("X-API-Key", "your_api_key"); using var form = new MultipartFormDataContent { { new ByteArrayContent(File.ReadAllBytes("input.pdf")), "file", "input.pdf" }, { new ByteArrayContent(File.ReadAllBytes("logo.png")), "image", "logo.png" }, { new StringContent("60"), "transparency" }, }; var response = await client.PostAsync( "https://api.pdfblocks.com/v1/add_image_watermark", form); response.EnsureSuccessStatusCode(); await File.WriteAllBytesAsync( "watermarked.pdf", await response.Content.ReadAsByteArrayAsync()); ``` </CodeGroup> ## Response On success, the response is `200 OK` with the watermarked PDF as the body: ```http HTTP/1.1 200 OK Content-Type: application/pdf Content-Length: 51820 ``` The output preserves the input's page count and dimensions: only the watermark is added. Stream the body straight to a file, as the examples above do; nothing is stored on our side. ## Errors Failed requests return an `application/problem+json` body. The most common one for this endpoint is a `400`, returned when a parameter is invalid or `image` isn't a supported format. The `errors` object names each field: ```json { "type": "https://www.pdfblocks.com/docs/api/v1/error/400", "title": "One or more validation errors occurred.", "status": 400, "errors": { "image": ["The image must be a PNG or JPEG file."] } } ``` A missing or invalid `X-API-Key` returns a `401`. See [Errors](/docs/api/errors) for every status code and the full response shape. ## Recipes Common variations. Expand one to see it in every language. <AccordionGroup> <Accordion title="A faint logo on every page"> <CodeGroup> ```bash title="cURL" curl https://api.pdfblocks.com/v1/add_image_watermark \ -H 'X-API-Key: your_api_key' \ -F file=@input.pdf \ -F image=@logo.png \ -F transparency=85 \ -o faint.pdf ``` ```python title="Python" import requests with open('input.pdf', 'rb') as file, open('logo.png', 'rb') as image: response = requests.post( 'https://api.pdfblocks.com/v1/add_image_watermark', headers={'X-API-Key': 'your_api_key'}, files={'file': file, 'image': image}, data={'transparency': 85}, ) response.raise_for_status() with open('faint.pdf', 'wb') as output: output.write(response.content) ``` ```javascript title="Node.js" import { readFile, writeFile } from 'node:fs/promises'; const body = new FormData(); body.set('file', new Blob([await readFile('input.pdf')]), 'input.pdf'); body.set('image', new Blob([await readFile('logo.png')]), 'logo.png'); body.set('transparency', '85'); const response = await fetch('https://api.pdfblocks.com/v1/add_image_watermark', { method: 'POST', headers: { 'X-API-Key': 'your_api_key' }, body, }); if (!response.ok) throw new Error(`Request failed: ${response.status}`); await writeFile('faint.pdf', Buffer.from(await response.arrayBuffer())); ``` ```php title="PHP" <?php $ch = curl_init('https://api.pdfblocks.com/v1/add_image_watermark'); curl_setopt_array($ch, [ CURLOPT_RETURNTRANSFER => true, CURLOPT_HTTPHEADER => ['X-API-Key: your_api_key'], CURLOPT_POST => true, CURLOPT_POSTFIELDS => [ 'file' => new CURLFile('input.pdf', 'application/pdf'), 'image' => new CURLFile('logo.png', 'image/png'), 'transparency' => '85', ], ]); $pdf = curl_exec($ch); if (curl_getinfo($ch, CURLINFO_HTTP_CODE) === 200) { file_put_contents('faint.pdf', $pdf); } ``` ```ruby title="Ruby" require 'http' response = HTTP .headers('X-API-Key' => 'your_api_key') .post('https://api.pdfblocks.com/v1/add_image_watermark', form: { file: HTTP::FormData::File.new('input.pdf'), image: HTTP::FormData::File.new('logo.png'), transparency: '85', }) File.write('faint.pdf', response.body) if response.status.success? ``` ```go title="Go" package main import ( "bytes" "io" "mime/multipart" "net/http" "os" ) func main() { var buf bytes.Buffer form := multipart.NewWriter(&buf) file, _ := os.Open("input.pdf") defer file.Close() filePart, _ := form.CreateFormFile("file", "input.pdf") io.Copy(filePart, file) image, _ := os.Open("logo.png") defer image.Close() imagePart, _ := form.CreateFormFile("image", "logo.png") io.Copy(imagePart, image) form.WriteField("transparency", "85") form.Close() req, _ := http.NewRequest("POST", "https://api.pdfblocks.com/v1/add_image_watermark", &buf) req.Header.Set("Content-Type", form.FormDataContentType()) req.Header.Set("X-API-Key", "your_api_key") res, _ := http.DefaultClient.Do(req) defer res.Body.Close() out, _ := os.Create("faint.pdf") defer out.Close() io.Copy(out, res.Body) } ``` ```csharp title="C#" using var client = new HttpClient(); client.DefaultRequestHeaders.Add("X-API-Key", "your_api_key"); using var form = new MultipartFormDataContent { { new ByteArrayContent(File.ReadAllBytes("input.pdf")), "file", "input.pdf" }, { new ByteArrayContent(File.ReadAllBytes("logo.png")), "image", "logo.png" }, { new StringContent("85"), "transparency" }, }; var response = await client.PostAsync( "https://api.pdfblocks.com/v1/add_image_watermark", form); response.EnsureSuccessStatusCode(); await File.WriteAllBytesAsync( "faint.pdf", await response.Content.ReadAsByteArrayAsync()); ``` </CodeGroup> </Accordion> <Accordion title="A logo on the cover page only"> <CodeGroup> ```bash title="cURL" curl https://api.pdfblocks.com/v1/add_image_watermark \ -H 'X-API-Key: your_api_key' \ -F file=@input.pdf \ -F image=@logo.png \ -F pages='1' \ -o cover-stamped.pdf ``` ```python title="Python" import requests with open('input.pdf', 'rb') as file, open('logo.png', 'rb') as image: response = requests.post( 'https://api.pdfblocks.com/v1/add_image_watermark', headers={'X-API-Key': 'your_api_key'}, files={'file': file, 'image': image}, data={'pages': '1'}, ) response.raise_for_status() with open('cover-stamped.pdf', 'wb') as output: output.write(response.content) ``` ```javascript title="Node.js" import { readFile, writeFile } from 'node:fs/promises'; const body = new FormData(); body.set('file', new Blob([await readFile('input.pdf')]), 'input.pdf'); body.set('image', new Blob([await readFile('logo.png')]), 'logo.png'); body.set('pages', '1'); const response = await fetch('https://api.pdfblocks.com/v1/add_image_watermark', { method: 'POST', headers: { 'X-API-Key': 'your_api_key' }, body, }); if (!response.ok) throw new Error(`Request failed: ${response.status}`); await writeFile('cover-stamped.pdf', Buffer.from(await response.arrayBuffer())); ``` ```php title="PHP" <?php $ch = curl_init('https://api.pdfblocks.com/v1/add_image_watermark'); curl_setopt_array($ch, [ CURLOPT_RETURNTRANSFER => true, CURLOPT_HTTPHEADER => ['X-API-Key: your_api_key'], CURLOPT_POST => true, CURLOPT_POSTFIELDS => [ 'file' => new CURLFile('input.pdf', 'application/pdf'), 'image' => new CURLFile('logo.png', 'image/png'), 'pages' => '1', ], ]); $pdf = curl_exec($ch); if (curl_getinfo($ch, CURLINFO_HTTP_CODE) === 200) { file_put_contents('cover-stamped.pdf', $pdf); } ``` ```ruby title="Ruby" require 'http' response = HTTP .headers('X-API-Key' => 'your_api_key') .post('https://api.pdfblocks.com/v1/add_image_watermark', form: { file: HTTP::FormData::File.new('input.pdf'), image: HTTP::FormData::File.new('logo.png'), pages: '1', }) File.write('cover-stamped.pdf', response.body) if response.status.success? ``` ```go title="Go" package main import ( "bytes" "io" "mime/multipart" "net/http" "os" ) func main() { var buf bytes.Buffer form := multipart.NewWriter(&buf) file, _ := os.Open("input.pdf") defer file.Close() filePart, _ := form.CreateFormFile("file", "input.pdf") io.Copy(filePart, file) image, _ := os.Open("logo.png") defer image.Close() imagePart, _ := form.CreateFormFile("image", "logo.png") io.Copy(imagePart, image) form.WriteField("pages", "1") form.Close() req, _ := http.NewRequest("POST", "https://api.pdfblocks.com/v1/add_image_watermark", &buf) req.Header.Set("Content-Type", form.FormDataContentType()) req.Header.Set("X-API-Key", "your_api_key") res, _ := http.DefaultClient.Do(req) defer res.Body.Close() out, _ := os.Create("cover-stamped.pdf") defer out.Close() io.Copy(out, res.Body) } ``` ```csharp title="C#" using var client = new HttpClient(); client.DefaultRequestHeaders.Add("X-API-Key", "your_api_key"); using var form = new MultipartFormDataContent { { new ByteArrayContent(File.ReadAllBytes("input.pdf")), "file", "input.pdf" }, { new ByteArrayContent(File.ReadAllBytes("logo.png")), "image", "logo.png" }, { new StringContent("1"), "pages" }, }; var response = await client.PostAsync( "https://api.pdfblocks.com/v1/add_image_watermark", form); response.EnsureSuccessStatusCode(); await File.WriteAllBytesAsync( "cover-stamped.pdf", await response.Content.ReadAsByteArrayAsync()); ``` </CodeGroup> </Accordion> </AccordionGroup> ## Related actions <CardGroup cols={2}> <Card title="Add a text watermark" href="/docs/api/add-text-watermark-to-pdf"> Stamp text instead of an image. </Card> <Card title="Add a password" href="/docs/api/add-password-to-pdf"> Encrypt the watermarked document. </Card> <Card title="Merge documents" href="/docs/api/merge-pdf-documents"> Combine files before watermarking. </Card> <Card title="Extract pages" href="/docs/api/extract-pages-from-pdf"> Pull out the stamped pages. </Card> </CardGroup>