# Merge PDF documents

Combine several PDF documents into one, in the order you supply them. Send as many files as you need in a single call; nothing is stored afterwards.

Combine several PDF documents into one. The files are merged in the exact order
they appear in the request, so you control the final page sequence. Supply as
many files as you need in a single call. The API is stateless: your document is
processed in-region and never stored.

## Endpoint

<Endpoint method="POST" path="/v1/merge_documents" />

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/merge_documents`      |
| United States  | `https://us.api.pdfblocks.com/v1/merge_documents`   |
| US HIPAA       | `https://hipaa.api.pdfblocks.com/v1/merge_documents` |
| European Union | `https://eu.api.pdfblocks.com/v1/merge_documents`   |
| United Kingdom | `https://uk.api.pdfblocks.com/v1/merge_documents`   |
| Canada         | `https://ca.api.pdfblocks.com/v1/merge_documents`   |
| Australia      | `https://au.api.pdfblocks.com/v1/merge_documents`   |
| Japan          | `https://jp.api.pdfblocks.com/v1/merge_documents`   |
| India          | `https://in.api.pdfblocks.com/v1/merge_documents`   |
| Brazil         | `https://br.api.pdfblocks.com/v1/merge_documents`   |

## 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 documents, sent as repeated `file` parts. Provide at least one;
  supply as many files as you need in a single request. The documents are merged
  in the exact order the parts appear in the request. See
  [Working with files](/docs/api/working-with-files) for how to send multiple
  `file` parts.
</ParamField>

## Examples

Merge three PDFs into one, in order:

<CodeGroup>

```bash title="cURL"
curl https://api.pdfblocks.com/v1/merge_documents \
  -H 'X-API-Key: your_api_key' \
  -F file=@chapter-1.pdf \
  -F file=@chapter-2.pdf \
  -F file=@chapter-3.pdf \
  -o merged.pdf
```

```python title="Python"
# pip install requests
import requests

files = [
    ('file', open('chapter-1.pdf', 'rb')),
    ('file', open('chapter-2.pdf', 'rb')),
    ('file', open('chapter-3.pdf', 'rb')),
]

response = requests.post(
    'https://api.pdfblocks.com/v1/merge_documents',
    headers={'X-API-Key': 'your_api_key'},
    files=files,
)

response.raise_for_status()
with open('merged.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.append('file', new Blob([await readFile('chapter-1.pdf')]), 'chapter-1.pdf');
body.append('file', new Blob([await readFile('chapter-2.pdf')]), 'chapter-2.pdf');
body.append('file', new Blob([await readFile('chapter-3.pdf')]), 'chapter-3.pdf');

const response = await fetch('https://api.pdfblocks.com/v1/merge_documents', {
  method: 'POST',
  headers: { 'X-API-Key': 'your_api_key' },
  body,
});

if (!response.ok) throw new Error(`Request failed: ${response.status}`);
await writeFile('merged.pdf', Buffer.from(await response.arrayBuffer()));
```

```php title="PHP"
<?php
// composer require guzzlehttp/guzzle
require 'vendor/autoload.php';

use GuzzleHttp\Client;

// Repeat the `file` part once per document: they merge in the order sent.
$response = (new Client())->post('https://api.pdfblocks.com/v1/merge_documents', [
    'headers' => ['X-API-Key' => 'your_api_key'],
    'multipart' => [
        ['name' => 'file', 'contents' => fopen('chapter-1.pdf', 'r'), 'filename' => 'chapter-1.pdf'],
        ['name' => 'file', 'contents' => fopen('chapter-2.pdf', 'r'), 'filename' => 'chapter-2.pdf'],
        ['name' => 'file', 'contents' => fopen('chapter-3.pdf', 'r'), 'filename' => 'chapter-3.pdf'],
    ],
]);

if ($response->getStatusCode() === 200) {
    file_put_contents('merged.pdf', $response->getBody());
}
```

```ruby title="Ruby"
# gem install http
require 'http'

response = HTTP
  .headers('X-API-Key' => 'your_api_key')
  .post('https://api.pdfblocks.com/v1/merge_documents', form: {
    file: [
      HTTP::FormData::File.new('chapter-1.pdf'),
      HTTP::FormData::File.new('chapter-2.pdf'),
      HTTP::FormData::File.new('chapter-3.pdf'),
    ],
  })

File.write('merged.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)

	for _, name := range []string{"chapter-1.pdf", "chapter-2.pdf", "chapter-3.pdf"} {
		file, _ := os.Open(name)
		part, _ := form.CreateFormFile("file", name)
		io.Copy(part, file)
		file.Close()
	}
	form.Close()

	req, _ := http.NewRequest("POST", "https://api.pdfblocks.com/v1/merge_documents", &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("merged.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("chapter-1.pdf")), "file", "chapter-1.pdf" },
    { new ByteArrayContent(File.ReadAllBytes("chapter-2.pdf")), "file", "chapter-2.pdf" },
    { new ByteArrayContent(File.ReadAllBytes("chapter-3.pdf")), "file", "chapter-3.pdf" },
};

var response = await client.PostAsync(
    "https://api.pdfblocks.com/v1/merge_documents", form);
response.EnsureSuccessStatusCode();
await File.WriteAllBytesAsync(
    "merged.pdf", await response.Content.ReadAsByteArrayAsync());
```

</CodeGroup>

## Response

On success, the response is `200 OK` with the merged PDF as the body:

```http
HTTP/1.1 200 OK
Content-Type: application/pdf
Content-Length: 96124
```

The output is a single PDF whose page count is the sum of the inputs', laid out
in request order. 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 one of the `file` parts isn't a
readable PDF. The `errors` object names the field:

```json
{
  "type": "https://www.pdfblocks.com/docs/api/v1/error/400",
  "title": "One or more validation errors occurred.",
  "status": 400,
  "errors": {
    "file": ["Could not parse the PDF document. The file may be invalid or corrupt."]
  }
}
```

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="Put a cover page in front of a report">

<CodeGroup>

```bash title="cURL"
curl https://api.pdfblocks.com/v1/merge_documents \
  -H 'X-API-Key: your_api_key' \
  -F file=@cover.pdf \
  -F file=@report.pdf \
  -o report-with-cover.pdf
```

```python title="Python"
import requests

files = [
    ('file', open('cover.pdf', 'rb')),
    ('file', open('report.pdf', 'rb')),
]

response = requests.post(
    'https://api.pdfblocks.com/v1/merge_documents',
    headers={'X-API-Key': 'your_api_key'},
    files=files,
)

response.raise_for_status()
with open('report-with-cover.pdf', 'wb') as output:
    output.write(response.content)
```

```javascript title="Node.js"
import { readFile, writeFile } from 'node:fs/promises';

const body = new FormData();
body.append('file', new Blob([await readFile('cover.pdf')]), 'cover.pdf');
body.append('file', new Blob([await readFile('report.pdf')]), 'report.pdf');

const response = await fetch('https://api.pdfblocks.com/v1/merge_documents', {
  method: 'POST',
  headers: { 'X-API-Key': 'your_api_key' },
  body,
});

if (!response.ok) throw new Error(`Request failed: ${response.status}`);
await writeFile('report-with-cover.pdf', Buffer.from(await response.arrayBuffer()));
```

```php title="PHP"
<?php
// composer require guzzlehttp/guzzle
require 'vendor/autoload.php';

use GuzzleHttp\Client;

$response = (new Client())->post('https://api.pdfblocks.com/v1/merge_documents', [
    'headers' => ['X-API-Key' => 'your_api_key'],
    'multipart' => [
        ['name' => 'file', 'contents' => fopen('cover.pdf', 'r'), 'filename' => 'cover.pdf'],
        ['name' => 'file', 'contents' => fopen('report.pdf', 'r'), 'filename' => 'report.pdf'],
    ],
]);

if ($response->getStatusCode() === 200) {
    file_put_contents('report-with-cover.pdf', $response->getBody());
}
```

```ruby title="Ruby"
require 'http'

response = HTTP
  .headers('X-API-Key' => 'your_api_key')
  .post('https://api.pdfblocks.com/v1/merge_documents', form: {
    file: [
      HTTP::FormData::File.new('cover.pdf'),
      HTTP::FormData::File.new('report.pdf'),
    ],
  })

File.write('report-with-cover.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)

	for _, name := range []string{"cover.pdf", "report.pdf"} {
		file, _ := os.Open(name)
		part, _ := form.CreateFormFile("file", name)
		io.Copy(part, file)
		file.Close()
	}
	form.Close()

	req, _ := http.NewRequest("POST", "https://api.pdfblocks.com/v1/merge_documents", &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("report-with-cover.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("cover.pdf")), "file", "cover.pdf" },
    { new ByteArrayContent(File.ReadAllBytes("report.pdf")), "file", "report.pdf" },
};

var response = await client.PostAsync(
    "https://api.pdfblocks.com/v1/merge_documents", form);
response.EnsureSuccessStatusCode();
await File.WriteAllBytesAsync(
    "report-with-cover.pdf", await response.Content.ReadAsByteArrayAsync());
```

</CodeGroup>

</Accordion>

</AccordionGroup>

## Related actions

<CardGroup cols={2}>

<Card title="Extract pages" href="/docs/api/extract-pages-from-pdf">
  Pull a subset of pages out of the merged file.
</Card>

<Card title="Reorder pages" href="/docs/api/reorder-pages-of-pdf">
  Rearrange pages after merging.
</Card>

<Card title="Split at page" href="/docs/api/split-pdf-at-page">
  Break the combined document back apart.
</Card>

<Card title="Add a text watermark" href="/docs/api/add-text-watermark-to-pdf">
  Stamp the merged document.
</Card>

</CardGroup>