PDF watermark API

Add custom text or image watermarks to PDF documents using a single API call. Use watermarking for branding, confidential stamps, ownership marks, document tracking, and other document-protection workflows.

Try for free

Text and image watermarking for protection and branding

Apply text or image watermarks such as company logos, confidential stamps, ownership marks, or custom messages to any page or section of a PDF.

Built for API-driven document workflows

Use REST, Postman, curl, JavaScript, Python, Java, C#, PHP, or HTTP to add watermarks in your own platform without building custom document processing infrastructure.

Automate watermarking at scale

Use watermarking for branded exports, confidential document delivery, ownership labeling, and automated protection workflows across generated or uploaded PDFs.

Try it out

This example will watermark all the pages of your document with the supplied logo.

Try it out in three steps

Add document.pdf and logo.png to your project folder.
Run the code from the same folder.
Open result.pdf to see the output.

Advanced API

curl -X POST https://api.nutrient.io/processor/watermark \
  -H "Authorization: Bearer your_api_key_here" \
  -o result.pdf \
  --fail \
  -F file=@document.pdf \
  -F logo=@logo.png \
  -F data='{
      "image": "logo",
      "width": "25%"
    }'

curl -X POST https://api.nutrient.io/processor/watermark ^
  -H "Authorization: Bearer your_api_key_here" ^
  -o result.pdf ^
  --fail ^
  -F file=@document.pdf ^
  -F logo=@logo.png ^
  -F data="{\"image\": \"logo\", \"width\": \"25%\"}"

package com.example.pspdfkit;

import java.io.File;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;

import org.json.JSONArray;
import org.json.JSONObject;

import okhttp3.MediaType;
import okhttp3.MultipartBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public final class PspdfkitApiExample {
  public static void main(final String[] args) throws IOException {
    final RequestBody body = new MultipartBody.Builder()
      .setType(MultipartBody.FORM)
      .addFormDataPart(
        "file",
        "document.pdf",
        RequestBody.create(
          MediaType.parse("application/pdf"),
          new File("document.pdf")
        )
      )
      .addFormDataPart(
        "logo",
        "logo.png",
        RequestBody.create(
          MediaType.parse("image/png"),
          new File("logo.png")
        )
      )
      .addFormDataPart(
        "data",
        new JSONObject()
          .put("image", "logo")
          .put("width", "25%").toString()
      )
      .build();

    final Request request = new Request.Builder()
      .url("https://api.nutrient.io/processor/watermark")
      .method("POST", body)
      .addHeader("Authorization", "Bearer your_api_key_here")
      .build();

    final OkHttpClient client = new OkHttpClient()
      .newBuilder()
      .build();

    final Response response = client.newCall(request).execute();

    if (response.isSuccessful()) {
      Files.copy(
        response.body().byteStream(),
        FileSystems.getDefault().getPath("result.pdf"),
        StandardCopyOption.REPLACE_EXISTING
      );
    } else {
      // Handle the error
      throw new IOException(response.body().string());
    }
  }
}

using System;
using System.IO;
using System.Net;
using RestSharp;

namespace PspdfkitApiDemo
{
  class Program
  {
    static void Main(string[] args)
    {
      var client = new RestClient("https://api.nutrient.io/processor/watermark");

      var request = new RestRequest(Method.POST)
        .AddHeader("Authorization", "Bearer your_api_key_here")
        .AddFile("file", "document.pdf")
        .AddFile("logo", "logo.png")
        .AddParameter("data", new JsonObject
        {
          ["image"] = "logo",
          ["width"] = "25%"
        }.ToString());

      request.AdvancedResponseWriter = (responseStream, response) =>
      {
        if (response.StatusCode == HttpStatusCode.OK)
        {
          using (responseStream)
          {
            using var outputFileWriter = File.OpenWrite("result.pdf");
            responseStream.CopyTo(outputFileWriter);
          }
        }
        else
        {
          var responseStreamReader = new StreamReader(responseStream);
          Console.Write(responseStreamReader.ReadToEnd());
        }
      };

      client.Execute(request);
    }
  }
}

// This code requires Node.js. Do not run this code directly in a web browser.

const axios = require('axios')
const FormData = require('form-data')
const fs = require('fs')

const formData = new FormData()
formData.append('data', JSON.stringify({
  image: "logo",
  width: "25%"
}))
formData.append('file', fs.createReadStream('document.pdf'))
formData.append('logo', fs.createReadStream('logo.png'))

;(async () => {
  try {
    const response = await axios.post('https://api.nutrient.io/processor/watermark', formData, {
      headers: formData.getHeaders({
        'Authorization': 'Bearer your_api_key_here'
      }),
      responseType: "stream"
    })

    response.data.pipe(fs.createWriteStream("result.pdf"))
  } catch (e) {
    const errorString = await streamToString(e.response.data)
    console.log(errorString)
  }
})()

function streamToString(stream) {
  const chunks = []
  return new Promise((resolve, reject) => {
    stream.on("data", (chunk) => chunks.push(Buffer.from(chunk)))
    stream.on("error", (err) => reject(err))
    stream.on("end", () => resolve(Buffer.concat(chunks).toString("utf8")))
  })
}

import requests
import json

response = requests.request(
  'POST',
  'https://api.nutrient.io/processor/watermark',
  headers = {
    'Authorization': 'Bearer your_api_key_here'
  },
  files = {
    'file': open('document.pdf', 'rb'),
    'logo': open('logo.png', 'rb')
  },
  data = {
    'data': json.dumps({
      'image': 'logo',
      'width': '25%'
    })
  },
  stream = True
)

if response.ok:
  with open('result.pdf', 'wb') as fd:
    for chunk in response.iter_content(chunk_size=8096):
      fd.write(chunk)
else:
  print(response.text)
  exit()

<?php

$FileHandle = fopen('result.pdf', 'w+');

$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => 'https://api.nutrient.io/processor/watermark',
  CURLOPT_CUSTOMREQUEST => 'POST',
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => '',
  CURLOPT_POSTFIELDS => array(
    'data' => '{
      "image": "logo",
      "width": "25%"
    }',
    'file' => new CURLFILE('document.pdf'),
    'logo' => new CURLFILE('logo.png')
  ),
  CURLOPT_HTTPHEADER => array(
    'Authorization: Bearer your_api_key_here'
  ),
  CURLOPT_FILE => $FileHandle,
));

$response = curl_exec($curl);

curl_close($curl);

fclose($FileHandle);

POST https://api.nutrient.io/processor/watermark HTTP/1.1
Content-Type: multipart/form-data; boundary=--customboundary
Authorization: Bearer your_api_key_here

--customboundary
Content-Disposition: form-data; name="data"
Content-Type: application/json

{
  "image": "logo",
  "width": "25%"
}
--customboundary
Content-Disposition: form-data; name="file"; filename="document.pdf"
Content-Type: application/pdf

(file data)
--customboundary
Content-Disposition: form-data; name="logo"; filename="logo.png"
Content-Type: image/png

(logo data)
--customboundary--

curl -X POST https://api.nutrient.io/build \
  -H "Authorization: Bearer your_api_key_here" \
  -o result.pdf \
  --fail \
  -F document=@document.pdf \
  -F logo=@logo.png \
  -F instructions='{
      "parts": [
        {
          "file": "document"
        }
      ],
      "actions": [
        {
          "type": "watermark",
          "image": "logo",
          "width": "25%"
        }
      ]
    }'

curl -X POST https://api.nutrient.io/build ^
  -H "Authorization: Bearer your_api_key_here" ^
  -o result.pdf ^
  --fail ^
  -F document=@document.pdf ^
  -F logo=@logo.png ^
  -F instructions="{\"parts\": [{\"file\": \"document\"}], \"actions\": [{\"type\": \"watermark\", \"image\": \"logo\", \"width\": \"25%\"}]}"

package com.example.pspdfkit;

import java.io.File;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;

import org.json.JSONArray;
import org.json.JSONObject;

import okhttp3.MediaType;
import okhttp3.MultipartBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public final class PspdfkitApiExample {
  public static void main(final String[] args) throws IOException {
    final RequestBody body = new MultipartBody.Builder()
      .setType(MultipartBody.FORM)
      .addFormDataPart(
        "document",
        "document.pdf",
        RequestBody.create(
          MediaType.parse("application/pdf"),
          new File("document.pdf")
        )
      )
      .addFormDataPart(
        "logo",
        "logo.png",
        RequestBody.create(
          MediaType.parse("image/png"),
          new File("logo.png")
        )
      )
      .addFormDataPart(
        "instructions",
        new JSONObject()
          .put("parts", new JSONArray()
            .put(new JSONObject()
              .put("file", "document")
            )
          )
          .put("actions", new JSONArray()
            .put(new JSONObject()
              .put("type", "watermark")
              .put("image", "logo")
              .put("width", "25%")
            )
          ).toString()
      )
      .build();

    final Request request = new Request.Builder()
      .url("https://api.nutrient.io/build")
      .method("POST", body)
      .addHeader("Authorization", "Bearer your_api_key_here")
      .build();

    final OkHttpClient client = new OkHttpClient()
      .newBuilder()
      .build();

    final Response response = client.newCall(request).execute();

    if (response.isSuccessful()) {
      Files.copy(
        response.body().byteStream(),
        FileSystems.getDefault().getPath("result.pdf"),
        StandardCopyOption.REPLACE_EXISTING
      );
    } else {
      // Handle the error
      throw new IOException(response.body().string());
    }
  }
}

using System;
using System.IO;
using System.Net;
using RestSharp;

namespace PspdfkitApiDemo
{
  class Program
  {
    static void Main(string[] args)
    {
      var client = new RestClient("https://api.nutrient.io/build");

      var request = new RestRequest(Method.POST)
        .AddHeader("Authorization", "Bearer your_api_key_here")
        .AddFile("document", "document.pdf")
        .AddFile("logo", "logo.png")
        .AddParameter("instructions", new JsonObject
        {
          ["parts"] = new JsonArray
          {
            new JsonObject
            {
              ["file"] = "document"
            }
          },
          ["actions"] = new JsonArray
          {
            new JsonObject
            {
              ["type"] = "watermark",
              ["image"] = "logo",
              ["width"] = "25%"
            }
          }
        }.ToString());

      request.AdvancedResponseWriter = (responseStream, response) =>
      {
        if (response.StatusCode == HttpStatusCode.OK)
        {
          using (responseStream)
          {
            using var outputFileWriter = File.OpenWrite("result.pdf");
            responseStream.CopyTo(outputFileWriter);
          }
        }
        else
        {
          var responseStreamReader = new StreamReader(responseStream);
          Console.Write(responseStreamReader.ReadToEnd());
        }
      };

      client.Execute(request);
    }
  }
}

// This code requires Node.js. Do not run this code directly in a web browser.

const axios = require('axios')
const FormData = require('form-data')
const fs = require('fs')

const formData = new FormData()
formData.append('instructions', JSON.stringify({
  parts: [
    {
      file: "document"
    }
  ],
  actions: [
    {
      type: "watermark",
      image: "logo",
      width: "25%"
    }
  ]
}))
formData.append('document', fs.createReadStream('document.pdf'))
formData.append('logo', fs.createReadStream('logo.png'))

;(async () => {
  try {
    const response = await axios.post('https://api.nutrient.io/build', formData, {
      headers: formData.getHeaders({
        'Authorization': 'Bearer your_api_key_here'
      }),
      responseType: "stream"
    })

    response.data.pipe(fs.createWriteStream("result.pdf"))
  } catch (e) {
    const errorString = await streamToString(e.response.data)
    console.log(errorString)
  }
})()

function streamToString(stream) {
  const chunks = []
  return new Promise((resolve, reject) => {
    stream.on("data", (chunk) => chunks.push(Buffer.from(chunk)))
    stream.on("error", (err) => reject(err))
    stream.on("end", () => resolve(Buffer.concat(chunks).toString("utf8")))
  })
}

import requests
import json

response = requests.request(
  'POST',
  'https://api.nutrient.io/build',
  headers = {
    'Authorization': 'Bearer your_api_key_here'
  },
  files = {
    'document': open('document.pdf', 'rb'),
    'logo': open('logo.png', 'rb')
  },
  data = {
    'instructions': json.dumps({
      'parts': [
        {
          'file': 'document'
        }
      ],
      'actions': [
        {
          'type': 'watermark',
          'image': 'logo',
          'width': '25%'
        }
      ]
    })
  },
  stream = True
)

if response.ok:
  with open('result.pdf', 'wb') as fd:
    for chunk in response.iter_content(chunk_size=8096):
      fd.write(chunk)
else:
  print(response.text)
  exit()

<?php

$FileHandle = fopen('result.pdf', 'w+');

$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => 'https://api.nutrient.io/build',
  CURLOPT_CUSTOMREQUEST => 'POST',
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => '',
  CURLOPT_POSTFIELDS => array(
    'instructions' => '{
      "parts": [
        {
          "file": "document"
        }
      ],
      "actions": [
        {
          "type": "watermark",
          "image": "logo",
          "width": "25%"
        }
      ]
    }',
    'document' => new CURLFILE('document.pdf'),
    'logo' => new CURLFILE('logo.png')
  ),
  CURLOPT_HTTPHEADER => array(
    'Authorization: Bearer your_api_key_here'
  ),
  CURLOPT_FILE => $FileHandle,
));

$response = curl_exec($curl);

curl_close($curl);

fclose($FileHandle);

POST https://api.nutrient.io/build HTTP/1.1
Content-Type: multipart/form-data; boundary=--customboundary
Authorization: Bearer your_api_key_here

--customboundary
Content-Disposition: form-data; name="instructions"
Content-Type: application/json

{
  "parts": [
    {
      "file": "document"
    }
  ],
  "actions": [
    {
      "type": "watermark",
      "image": "logo",
      "width": "25%"
    }
  ]
}
--customboundary
Content-Disposition: form-data; name="document"; filename="document.pdf"
Content-Type: application/pdf

(document data)
--customboundary
Content-Disposition: form-data; name="logo"; filename="logo.png"
Content-Type: image/png

(logo data)
--customboundary--

Start now

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Most common next steps

Connect watermark evaluation to getting started, pricing, trust, and broader Processor workflows

OPEN GETTING STARTED

Use the following:

PDF security API If the workflow also needs password protection or access control

Get started:

Getting started For API key setup

Postman collection For the fastest first request

Supported languages For JavaScript, Python, Java, PHP, and HTTP implementation options

REST API reference For endpoint details

Platform resources:

Processor API pricing For credits

Security documentation For document handling and compliance review

Privacy documentation For data handling review

Processor API overview For broader DWS evaluation of image watermark, branding, and confidential watermark workflows

API comparison

BASIC

Watermark API

Straightforward API for adding watermarks to PDFs. Perfect for most use cases.

FEATURES

Simple request format
Minimal configuration required
Purpose-built for specific tasks

ADVANCED

Build API

Maximum flexibility and advanced features for complex workflows.

FEATURES

Multipart document support
Advanced actions and transformations
Workflow orchestration

Getting started

Learn how to use the watermark API’s key features.

GUIDES

Multiple watermarks

Single-page watermark

Aligning watermarks

Reference

Security is our top priority

No document storage

No input or resulting documents are stored on our infrastructure. All files are deleted as soon as a request finishes. Alternatively, check out our self-hosted product.

HTTPS encryption

All communication between your application and Nutrient is done via HTTPS to ensure your data is encrypted when it’s sent to us.

Safe payment processing

All payments are handled by Paddle. Nutrient DWS Processor API never has direct access to any of your payment data.

Frequently asked questions

What is a PDF watermark API?

A PDF watermark API lets you add text or image watermarks to PDF documents with a single API call. With Nutrient’s DWS Processor API, you can apply branding, confidential stamps, ownership marks, and other document-protection overlays without building your own document processing infrastructure.

How do I add a watermark to a PDF programmatically?

Send a request to the Nutrient DWS Processor API with your PDF and the watermark you want to apply, and the API returns the watermarked document. You can call it via REST, Postman, curl, JavaScript, Python, Java, C#, PHP, or plain HTTP.

Can I add image watermarks like a company logo?

Yes. You can apply image watermarks such as company logos, confidential stamps, or ownership marks — as well as custom text — to any page or section of a PDF.

Which programming languages does the watermark API support?

You can call the API from any language that can make HTTP requests. We provide quickstart examples for JavaScript, Python, Java, C# (.NET), and PHP, plus REST and a Postman collection to get your first request running faster.

Is there a free PDF watermark API?

Yes. You can start for free — sign up to receive processing credits and try the PDF watermark API before choosing a Processor API plan.

Ready to try it?

Create an account to get your DWS Processor API key and start making API calls.

START FOR FREE