HTML-to-Office API for converting HTML and CSS to DOCX, XLSX, and PPTX output

Use Nutrient DWS Processor API to convert HTML pages into Office document output including DOCX, XLSX, and PPTX. Start a free trial, test with Postman, and move to production with credit-based pricing.

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Try it out

This example will convert your uploaded HTML file to a DOCX document.

Try it out in three steps

Add an HTML file named index.html to your project folder.
Run the code from the same folder.
Open result.docx to see the output.

curl -X POST https://api.nutrient.io/build \
  -H "Authorization: Bearer your_api_key_here" \
  -o result.docx \
  --fail \
  -F document=@index.html \
  -F instructions='{
      "parts": [
        {
          "html": "document"
        }
      ],
      "output": {
        "type": "docx"
      }
    }'

curl -X POST https://api.nutrient.io/build ^
  -H "Authorization: Bearer your_api_key_here" ^
  -o result.docx ^
  --fail ^
  -F document=@index.html ^
  -F instructions="{\"parts\": [{\"html\": \"document\"}], \"output\": {\"type\": \"docx\"}}"

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",
        "index.html",
        RequestBody.create(
          MediaType.parse("text/html"),
          new File("index.html")
        )
      )
      .addFormDataPart(
        "instructions",
        new JSONObject()
          .put("parts", new JSONArray()
            .put(new JSONObject()
              .put("html", "document")
            )
          )
          .put("output", new JSONObject()
            .put("type", "docx")
          ).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.docx"),
        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", "index.html")
        .AddParameter("instructions", new JsonObject
        {
          ["parts"] = new JsonArray
          {
            new JsonObject
            {
              ["html"] = "document"
            }
          },
          ["output"] = new JsonObject
          {
            ["type"] = "docx"
          }
        }.ToString());

      request.AdvancedResponseWriter = (responseStream, response) =>
      {
        if (response.StatusCode == HttpStatusCode.OK)
        {
          using (responseStream)
          {
            using var outputFileWriter = File.OpenWrite("result.docx");
            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: [
    {
      html: "document"
    }
  ],
  output: {
    type: "docx"
  }
}))
formData.append('document', fs.createReadStream('index.html'))

;(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.docx"))
  } 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('index.html', 'rb')
  },
  data = {
    'instructions': json.dumps({
      'parts': [
        {
          'html': 'document'
        }
      ],
      'output': {
        'type': 'docx'
      }
    })
  },
  stream = True
)

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

<?php

$FileHandle = fopen('result.docx', '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": [
        {
          "html": "document"
        }
      ],
      "output": {
        "type": "docx"
      }
    }',
    'document' => new CURLFILE('index.html')
  ),
  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": [
    {
      "html": "document"
    }
  ],
  "output": {
    "type": "docx"
  }
}
--customboundary
Content-Disposition: form-data; name="document"; filename="index.html"
Content-Type: text/html

(document data)
--customboundary--

Try it out

This example will convert your uploaded HTML file to a PPTX document.

Try it out in three steps

Add an HTML file named index.html to your project folder.
Run the code from the same folder.
Open result.pptx in your project folder to view the results.

curl -X POST https://api.nutrient.io/build \
  -H "Authorization: Bearer your_api_key_here" \
  -o result.pptx \
  --fail \
  -F document=@index.html \
  -F instructions='{
      "parts": [
        {
          "html": "document"
        }
      ],
      "output": {
        "type": "pptx"
      }
    }'

curl -X POST https://api.nutrient.io/build ^
  -H "Authorization: Bearer your_api_key_here" ^
  -o result.pptx ^
  --fail ^
  -F document=@index.html ^
  -F instructions="{\"parts\": [{\"html\": \"document\"}], \"output\": {\"type\": \"pptx\"}}"

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",
        "index.html",
        RequestBody.create(
          MediaType.parse("text/html"),
          new File("index.html")
        )
      )
      .addFormDataPart(
        "instructions",
        new JSONObject()
          .put("parts", new JSONArray()
            .put(new JSONObject()
              .put("html", "document")
            )
          )
          .put("output", new JSONObject()
            .put("type", "pptx")
          ).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.pptx"),
        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", "index.html")
        .AddParameter("instructions", new JsonObject
        {
          ["parts"] = new JsonArray
          {
            new JsonObject
            {
              ["html"] = "document"
            }
          },
          ["output"] = new JsonObject
          {
            ["type"] = "pptx"
          }
        }.ToString());

      request.AdvancedResponseWriter = (responseStream, response) =>
      {
        if (response.StatusCode == HttpStatusCode.OK)
        {
          using (responseStream)
          {
            using var outputFileWriter = File.OpenWrite("result.pptx");
            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: [
    {
      html: "document"
    }
  ],
  output: {
    type: "pptx"
  }
}))
formData.append('document', fs.createReadStream('index.html'))

;(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.pptx"))
  } 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('index.html', 'rb')
  },
  data = {
    'instructions': json.dumps({
      'parts': [
        {
          'html': 'document'
        }
      ],
      'output': {
        'type': 'pptx'
      }
    })
  },
  stream = True
)

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

<?php

$FileHandle = fopen('result.pptx', '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": [
        {
          "html": "document"
        }
      ],
      "output": {
        "type": "pptx"
      }
    }',
    'document' => new CURLFILE('index.html')
  ),
  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": [
    {
      "html": "document"
    }
  ],
  "output": {
    "type": "pptx"
  }
}
--customboundary
Content-Disposition: form-data; name="document"; filename="index.html"
Content-Type: text/html

(document data)
--customboundary--

Try it out

This example will convert your uploaded HTML file to an XLSX document.

Try it out in three steps

Add an HTML file named index.html to your project folder.
Run the code from the same folder.
Open result.xlsx in your project folder to view the results.

curl -X POST https://api.nutrient.io/build \
  -H "Authorization: Bearer your_api_key_here" \
  -o result.xlsx \
  --fail \
  -F document=@index.html \
  -F instructions='{
      "parts": [
        {
          "html": "document"
        }
      ],
      "output": {
        "type": "xlsx"
      }
    }'

curl -X POST https://api.nutrient.io/build ^
  -H "Authorization: Bearer your_api_key_here" ^
  -o result.xlsx ^
  --fail ^
  -F document=@index.html ^
  -F instructions="{\"parts\": [{\"html\": \"document\"}], \"output\": {\"type\": \"xlsx\"}}"

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",
        "index.html",
        RequestBody.create(
          MediaType.parse("text/html"),
          new File("index.html")
        )
      )
      .addFormDataPart(
        "instructions",
        new JSONObject()
          .put("parts", new JSONArray()
            .put(new JSONObject()
              .put("html", "document")
            )
          )
          .put("output", new JSONObject()
            .put("type", "xlsx")
          ).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.xlsx"),
        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", "index.html")
        .AddParameter("instructions", new JsonObject
        {
          ["parts"] = new JsonArray
          {
            new JsonObject
            {
              ["html"] = "document"
            }
          },
          ["output"] = new JsonObject
          {
            ["type"] = "xlsx"
          }
        }.ToString());

      request.AdvancedResponseWriter = (responseStream, response) =>
      {
        if (response.StatusCode == HttpStatusCode.OK)
        {
          using (responseStream)
          {
            using var outputFileWriter = File.OpenWrite("result.xlsx");
            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: [
    {
      html: "document"
    }
  ],
  output: {
    type: "xlsx"
  }
}))
formData.append('document', fs.createReadStream('index.html'))

;(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.xlsx"))
  } 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('index.html', 'rb')
  },
  data = {
    'instructions': json.dumps({
      'parts': [
        {
          'html': 'document'
        }
      ],
      'output': {
        'type': 'xlsx'
      }
    })
  },
  stream = True
)

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

<?php

$FileHandle = fopen('result.xlsx', '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": [
        {
          "html": "document"
        }
      ],
      "output": {
        "type": "xlsx"
      }
    }',
    'document' => new CURLFILE('index.html')
  ),
  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": [
    {
      "html": "document"
    }
  ],
  "output": {
    "type": "xlsx"
  }
}
--customboundary
Content-Disposition: form-data; name="document"; filename="index.html"
Content-Type: text/html

(document data)
--customboundary--

HTML DOCX

HTML XLSX

HTML PPTX

Broad HTML-to-Office conversion

Convert HTML into Word, Excel, and PowerPoint output for editing, collaboration, and distribution workflows.

API-first integration

Use REST, Postman, curl, JavaScript, Python, Java, C#, PHP, or HTTP to automate conversion inside larger document processing pipelines.

Part of the DWS Processor platform

This conversion is one action in the DWS Processor API. Combine it with other conversions, OCR, extraction, and editing in a single request.

Most common next steps

Connect this conversion to getting started, pricing, and the broader Processor API

OPEN GETTING STARTED

Use the following:

HTML to DOCX For specific Word format output

HTML to XLSX For specific Excel format output

HTML to PPTX For specific PowerPoint format output

HTML to PDF If the output should be PDF

Continue to:

Getting started For API key setup

Postman collection For the fastest first request

Processor API pricing For credits

Processor API overview For broader DWS evaluation

Frequently asked questions

What HTML and CSS does the API support as input?

The API accepts standard HTML markup with inline and embedded CSS for layout, typography, tables, and styling. You upload an HTML file along with any CSS or asset files, and the API renders it before converting to the selected Office format.

How do I convert HTML to DOCX programmatically?

Send a request to the DWS Processor API with your HTML input and DOCX as the target format. You can call it over REST, curl, Postman, or an SDK in JavaScript, Python, Java, C#, or PHP. See the getting started guide for API key setup, or the dedicated HTML-to-DOCX API for that specific conversion.

Is CSS styling preserved in the Office output?

Yes. The API renders your HTML and CSS and maps the result into the target Office format, preserving layout, fonts, tables, and styling as closely as the format allows. Some advanced CSS may render differently across DOCX, XLSX, and PPTX because each format has its own structural constraints.

When should I use HTML to Office instead of HTML to PDF?

Use HTML to Office when recipients need to edit or repurpose the output in Word, Excel, or PowerPoint — for example, DOCX, XLSX, or PPTX. Use the HTML-to-PDF API when you need a fixed, non-editable document for sharing, printing, or archiving.

Is there a free trial or sandbox to test conversions?

Yes. Start a free trial to get an API key and test conversions before moving to production. Production usage runs on credit-based pricing; see Processor API pricing for details.