Merge PDFs with the API

Combine multiple existing PDFs into one document. Send publicly accessible HTTPS URLs or Base64-encoded files in the required order, and receive the merged PDF or a temporary download link. Merge reports with their attachments or combine multiple invoices into one PDF.

Try it in the Playground

Upload PDFs or add PDF URLs, arrange them in the order you need, and merge them without writing code.

Try in Playground →

Endpoints

Method	Endpoint	Successful response
POST	/v1/tools/merge/direct	PDF bytes with Content-Type: application/pdf
POST	/v1/tools/merge/sync	JSON with result metadata and a download URL when using default storage

Both endpoints wait for merging to complete before responding.

Authentication

Use a conversion API key in the API-KEY header.

API-KEY: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX

Find your key on the API Credentials page in your Dashboard.

Merge PDFs from URLs

The examples combine two sample PDFs and save the result as merged.pdf. Replace the sample URLs with direct HTTPS URLs to your files. PDFs are merged in the order listed in inputs.

The examples use the Direct endpoint. To receive a download URL, replace /direct with /sync and read the response as JSON. The documentUrl field contains the download URL.

Request body

{
  "inputs": [
    {"url": "https://pdfbolt.com/samples/merge-sample-1.pdf"},
    {"url": "https://pdfbolt.com/samples/merge-sample-2.pdf"}
  ]
}

cURL

curl --fail --show-error \
  'https://api.pdfbolt.com/v1/tools/merge/direct' \
  -H 'API-KEY: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX' \
  -H 'Content-Type: application/json' \
  -d '{
  "inputs": [
    {"url": "https://pdfbolt.com/samples/merge-sample-1.pdf"},
    {"url": "https://pdfbolt.com/samples/merge-sample-2.pdf"}
  ]
}' \
  -o merged.pdf

Node.js

Requires Node.js 18 or later.

const fs = require('fs');

async function mergePdfs() {
    const requestData = {
        inputs: [
            {url: 'https://pdfbolt.com/samples/merge-sample-1.pdf'},
            {url: 'https://pdfbolt.com/samples/merge-sample-2.pdf'}
        ]
    };

    const response = await fetch('https://api.pdfbolt.com/v1/tools/merge/direct', {
        method: 'POST',
        headers: {
            'API-KEY': 'XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX',
            'Content-Type': 'application/json'
        },
        body: JSON.stringify(requestData)
    });

    if (!response.ok) {
        const errorText = await response.text();
        throw new Error(`HTTP ${response.status} - ${errorText}`);
    }

    const pdfBuffer = await response.arrayBuffer();
    fs.writeFileSync('merged.pdf', Buffer.from(pdfBuffer));
    console.log('PDFs merged successfully');
}

mergePdfs().catch(console.error);

Python

Install requests with pip install requests.

import requests

url = "https://api.pdfbolt.com/v1/tools/merge/direct"
headers = {
    "API-KEY": "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
    "Content-Type": "application/json"
}

data = {
    "inputs": [
        {"url": "https://pdfbolt.com/samples/merge-sample-1.pdf"},
        {"url": "https://pdfbolt.com/samples/merge-sample-2.pdf"}
    ]
}

try:
    response = requests.post(url, headers=headers, json=data)
    response.raise_for_status()

    with open('merged.pdf', 'wb') as f:
        f.write(response.content)
    print("PDFs merged successfully")

except requests.exceptions.HTTPError:
    print(f"HTTP {response.status_code}")
    print(f"Error Message: {response.text}")
except requests.exceptions.RequestException as e:
    print(f"Error: {e}")

PHP

Install Guzzle with composer require guzzlehttp/guzzle.

<?php

require __DIR__ . '/vendor/autoload.php';

use GuzzleHttp\Client;
use GuzzleHttp\Exception\RequestException;

$headers = [
    'API-KEY' => 'XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX',
    'Content-Type' => 'application/json',
];

$body = [
    'inputs' => [
        ['url' => 'https://pdfbolt.com/samples/merge-sample-1.pdf'],
        ['url' => 'https://pdfbolt.com/samples/merge-sample-2.pdf'],
    ],
];

try {
    $client = new Client();
    $response = $client->post('https://api.pdfbolt.com/v1/tools/merge/direct', [
        'headers' => $headers,
        'json' => $body,
    ]);

    file_put_contents('merged.pdf', (string) $response->getBody());
    echo "PDFs merged successfully\n";

} catch (RequestException $e) {
    if ($e->hasResponse()) {
        echo "HTTP " . $e->getResponse()->getStatusCode() . "\n";
        echo "Error Message: " . $e->getResponse()->getBody() . "\n";
    } else {
        echo "Error: " . $e->getMessage() . "\n";
    }
}

Java

Requires Java 17 or later.

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.file.Files;
import java.nio.file.Paths;

public class PDFBoltIntegration {
    public static void main(String[] args) throws Exception {
        String jsonBody = """
            {
                "inputs": [
                    {"url": "https://pdfbolt.com/samples/merge-sample-1.pdf"},
                    {"url": "https://pdfbolt.com/samples/merge-sample-2.pdf"}
                ]
            }
            """;

        var client = HttpClient.newHttpClient();
        var request = HttpRequest.newBuilder()
                .uri(URI.create("https://api.pdfbolt.com/v1/tools/merge/direct"))
                .header("API-KEY", "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")
                .header("Content-Type", "application/json")
                .POST(HttpRequest.BodyPublishers.ofString(jsonBody))
                .build();

        var response = client.send(request, HttpResponse.BodyHandlers.ofByteArray());

        if (response.statusCode() == 200) {
            Files.write(Paths.get("merged.pdf"), response.body());
            System.out.println("PDFs merged successfully");
        } else {
            System.err.println("HTTP " + response.statusCode());
            System.err.println("Error Message: " + new String(response.body()));
        }
    }
}

C#

Use a .NET 6 or later console project.

using System;
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

public class PDFBoltIntegration {
    public static async Task Main(string[] args) {
        using var client = new HttpClient();

        var requestData = new {
            inputs = new[] {
                new {url = "https://pdfbolt.com/samples/merge-sample-1.pdf"},
                new {url = "https://pdfbolt.com/samples/merge-sample-2.pdf"}
            }
        };

        using var request = new HttpRequestMessage {
            Method = HttpMethod.Post,
            RequestUri = new Uri("https://api.pdfbolt.com/v1/tools/merge/direct"),
            Content = new StringContent(
                JsonSerializer.Serialize(requestData),
                Encoding.UTF8,
                "application/json"
            )
        };

        request.Headers.Add("API-KEY", "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX");

        try {
            using var response = await client.SendAsync(request);

            if (!response.IsSuccessStatusCode) {
                var errorContent = await response.Content.ReadAsStringAsync();
                Console.WriteLine($"HTTP {(int)response.StatusCode}");
                Console.WriteLine($"Error Message: {errorContent}");
                return;
            }

            var pdfBytes = await response.Content.ReadAsByteArrayAsync();
            await File.WriteAllBytesAsync("merged.pdf", pdfBytes);
            Console.WriteLine("PDFs merged successfully");
        } catch (Exception ex) {
            Console.WriteLine($"Error: {ex.Message}");
        }
    }
}

Go

Requires Go 1.16 or later.

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "io"
    "log"
    "net/http"
    "os"
)

func main() {
    data := map[string]interface{}{
        "inputs": []map[string]interface{}{
            {"url": "https://pdfbolt.com/samples/merge-sample-1.pdf"},
            {"url": "https://pdfbolt.com/samples/merge-sample-2.pdf"},
        },
    }

    jsonBody, err := json.Marshal(data)
    if err != nil {
        log.Fatal(err)
    }

    req, err := http.NewRequest("POST", "https://api.pdfbolt.com/v1/tools/merge/direct", bytes.NewReader(jsonBody))
    if err != nil {
        log.Fatal(err)
    }
    req.Header.Add("API-KEY", "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")
    req.Header.Add("Content-Type", "application/json")

    resp, err := http.DefaultClient.Do(req)
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()

    if resp.StatusCode != http.StatusOK {
        body, err := io.ReadAll(resp.Body)
        if err != nil {
            log.Fatal(err)
        }
        fmt.Printf("HTTP %d\n", resp.StatusCode)
        fmt.Printf("Error Message: %s\n", string(body))
        return
    }

    file, err := os.Create("merged.pdf")
    if err != nil {
        log.Fatal(err)
    }
    defer file.Close()

    if _, err := io.Copy(file, resp.Body); err != nil {
        log.Fatal(err)
    }
    fmt.Println("PDFs merged successfully")
}

Rust

Add these dependencies to Cargo.toml:

[dependencies]
reqwest = { version = "0.13", features = ["json"] }
serde_json = "1"
tokio = { version = "1", features = ["full"] }

use reqwest::Client;
use serde_json::json;
use std::fs;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();
    let url = "https://api.pdfbolt.com/v1/tools/merge/direct";
    let request_data = json!({
        "inputs": [
            {"url": "https://pdfbolt.com/samples/merge-sample-1.pdf"},
            {"url": "https://pdfbolt.com/samples/merge-sample-2.pdf"}
        ]
    });

    let response = client
        .post(url)
        .header("API-KEY", "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")
        .header("Content-Type", "application/json")
        .json(&request_data)
        .send()
        .await?;

    if !response.status().is_success() {
        println!("HTTP {}", response.status().as_u16());
        let error_text = response.text().await?;
        println!("Error Message: {}", error_text);
        return Ok(());
    }

    let pdf_bytes = response.bytes().await?;
    fs::write("merged.pdf", pdf_bytes)?;
    println!("PDFs merged successfully");

    Ok(())
}

Merge Local PDF Files

Encode each PDF as Base64 and use the encoded data in the inputs[].pdf fields shown below, without the data:application/pdf;base64, prefix.

Request body

{
  "inputs": [
    {"pdf": "BASE64_FIRST_PDF"},
    {"pdf": "BASE64_SECOND_PDF"}
  ]
}

cURL

curl --fail --show-error \
  'https://api.pdfbolt.com/v1/tools/merge/direct' \
  -H 'API-KEY: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX' \
  -H 'Content-Type: application/json' \
  -d '{
  "inputs": [
    {"pdf": "BASE64_FIRST_PDF"},
    {"pdf": "BASE64_SECOND_PDF"}
  ]
}' \
  -o merged.pdf

Node.js

Requires Node.js 18 or later.

const fs = require('fs');

async function mergePdfs() {
    const requestData = {
        inputs: [
            {pdf: 'BASE64_FIRST_PDF'},
            {pdf: 'BASE64_SECOND_PDF'}
        ]
    };

    const response = await fetch('https://api.pdfbolt.com/v1/tools/merge/direct', {
        method: 'POST',
        headers: {
            'API-KEY': 'XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX',
            'Content-Type': 'application/json'
        },
        body: JSON.stringify(requestData)
    });

    if (!response.ok) {
        const errorText = await response.text();
        throw new Error(`HTTP ${response.status} - ${errorText}`);
    }

    const pdfBuffer = await response.arrayBuffer();
    fs.writeFileSync('merged.pdf', Buffer.from(pdfBuffer));
    console.log('PDFs merged successfully');
}

mergePdfs().catch(console.error);

Python

Install requests with pip install requests.

import requests

url = "https://api.pdfbolt.com/v1/tools/merge/direct"
headers = {
    "API-KEY": "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
    "Content-Type": "application/json"
}

data = {
    "inputs": [
        {"pdf": "BASE64_FIRST_PDF"},
        {"pdf": "BASE64_SECOND_PDF"}
    ]
}

try:
    response = requests.post(url, headers=headers, json=data)
    response.raise_for_status()

    with open('merged.pdf', 'wb') as f:
        f.write(response.content)
    print("PDFs merged successfully")

except requests.exceptions.HTTPError:
    print(f"HTTP {response.status_code}")
    print(f"Error Message: {response.text}")
except requests.exceptions.RequestException as e:
    print(f"Error: {e}")

PHP

Install Guzzle with composer require guzzlehttp/guzzle.

<?php

require __DIR__ . '/vendor/autoload.php';

use GuzzleHttp\Client;
use GuzzleHttp\Exception\RequestException;

$headers = [
    'API-KEY' => 'XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX',
    'Content-Type' => 'application/json',
];

$body = [
    'inputs' => [
        ['pdf' => 'BASE64_FIRST_PDF'],
        ['pdf' => 'BASE64_SECOND_PDF'],
    ],
];

try {
    $client = new Client();
    $response = $client->post('https://api.pdfbolt.com/v1/tools/merge/direct', [
        'headers' => $headers,
        'json' => $body,
    ]);

    file_put_contents('merged.pdf', (string) $response->getBody());
    echo "PDFs merged successfully\n";

} catch (RequestException $e) {
    if ($e->hasResponse()) {
        echo "HTTP " . $e->getResponse()->getStatusCode() . "\n";
        echo "Error Message: " . $e->getResponse()->getBody() . "\n";
    } else {
        echo "Error: " . $e->getMessage() . "\n";
    }
}

Java

Requires Java 17 or later.

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.file.Files;
import java.nio.file.Paths;

public class PDFBoltIntegration {
    public static void main(String[] args) throws Exception {
        String jsonBody = """
            {
                "inputs": [
                    {"pdf": "BASE64_FIRST_PDF"},
                    {"pdf": "BASE64_SECOND_PDF"}
                ]
            }
            """;

        var client = HttpClient.newHttpClient();
        var request = HttpRequest.newBuilder()
                .uri(URI.create("https://api.pdfbolt.com/v1/tools/merge/direct"))
                .header("API-KEY", "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")
                .header("Content-Type", "application/json")
                .POST(HttpRequest.BodyPublishers.ofString(jsonBody))
                .build();

        var response = client.send(request, HttpResponse.BodyHandlers.ofByteArray());

        if (response.statusCode() == 200) {
            Files.write(Paths.get("merged.pdf"), response.body());
            System.out.println("PDFs merged successfully");
        } else {
            System.err.println("HTTP " + response.statusCode());
            System.err.println("Error Message: " + new String(response.body()));
        }
    }
}

C#

Use a .NET 6 or later console project.

using System;
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

public class PDFBoltIntegration {
    public static async Task Main(string[] args) {
        using var client = new HttpClient();

        var requestData = new {
            inputs = new[] {
                new {pdf = "BASE64_FIRST_PDF"},
                new {pdf = "BASE64_SECOND_PDF"}
            }
        };

        using var request = new HttpRequestMessage {
            Method = HttpMethod.Post,
            RequestUri = new Uri("https://api.pdfbolt.com/v1/tools/merge/direct"),
            Content = new StringContent(
                JsonSerializer.Serialize(requestData),
                Encoding.UTF8,
                "application/json"
            )
        };

        request.Headers.Add("API-KEY", "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX");

        try {
            using var response = await client.SendAsync(request);

            if (!response.IsSuccessStatusCode) {
                var errorContent = await response.Content.ReadAsStringAsync();
                Console.WriteLine($"HTTP {(int)response.StatusCode}");
                Console.WriteLine($"Error Message: {errorContent}");
                return;
            }

            var pdfBytes = await response.Content.ReadAsByteArrayAsync();
            await File.WriteAllBytesAsync("merged.pdf", pdfBytes);
            Console.WriteLine("PDFs merged successfully");
        } catch (Exception ex) {
            Console.WriteLine($"Error: {ex.Message}");
        }
    }
}

Go

Requires Go 1.16 or later.

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "io"
    "log"
    "net/http"
    "os"
)

func main() {
    data := map[string]interface{}{
        "inputs": []map[string]interface{}{
            {"pdf": "BASE64_FIRST_PDF"},
            {"pdf": "BASE64_SECOND_PDF"},
        },
    }

    jsonBody, err := json.Marshal(data)
    if err != nil {
        log.Fatal(err)
    }

    req, err := http.NewRequest("POST", "https://api.pdfbolt.com/v1/tools/merge/direct", bytes.NewReader(jsonBody))
    if err != nil {
        log.Fatal(err)
    }
    req.Header.Add("API-KEY", "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")
    req.Header.Add("Content-Type", "application/json")

    resp, err := http.DefaultClient.Do(req)
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()

    if resp.StatusCode != http.StatusOK {
        body, err := io.ReadAll(resp.Body)
        if err != nil {
            log.Fatal(err)
        }
        fmt.Printf("HTTP %d\n", resp.StatusCode)
        fmt.Printf("Error Message: %s\n", string(body))
        return
    }

    file, err := os.Create("merged.pdf")
    if err != nil {
        log.Fatal(err)
    }
    defer file.Close()

    if _, err := io.Copy(file, resp.Body); err != nil {
        log.Fatal(err)
    }
    fmt.Println("PDFs merged successfully")
}

Rust

Add these dependencies to Cargo.toml:

[dependencies]
reqwest = { version = "0.13", features = ["json"] }
serde_json = "1"
tokio = { version = "1", features = ["full"] }

use reqwest::Client;
use serde_json::json;
use std::fs;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();
    let url = "https://api.pdfbolt.com/v1/tools/merge/direct";
    let request_data = json!({
        "inputs": [
            {"pdf": "BASE64_FIRST_PDF"},
            {"pdf": "BASE64_SECOND_PDF"}
        ]
    });

    let response = client
        .post(url)
        .header("API-KEY", "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")
        .header("Content-Type", "application/json")
        .json(&request_data)
        .send()
        .await?;

    if !response.status().is_success() {
        println!("HTTP {}", response.status().as_u16());
        let error_text = response.text().await?;
        println!("Error Message: {}", error_text);
        return Ok(());
    }

    let pdf_bytes = response.bytes().await?;
    fs::write("merged.pdf", pdf_bytes)?;
    println!("PDFs merged successfully");

    Ok(())
}

Request Parameters

Set the Content-Type header to application/json.

inputs

Type: array of objects

Required: Yes

Details: An array of 2–20 PDF sources in merge order. Each item must contain either url or pdf, not both. You can mix both source types in the same request. All pages from each source are included.

Usage:

{
  "inputs": [
    {"url": "https://pdfbolt.com/samples/merge-sample-1.pdf"},
    {"pdf": "BASE64_SECOND_PDF"}
  ]
}

inputs[].url

Type: string

Required: Yes, if pdf is omitted from the same item

Details: Direct, publicly accessible HTTPS URL of the input PDF. Maximum length: 2,048 characters.

URLs must not contain credentials or fragments such as #page=2. Redirects and private network addresses are not supported. Custom headers cannot be supplied when fetching the PDF.

inputs[].pdf

Type: string

Required: Yes, if url is omitted from the same item

Details: Base64-encoded contents of the input PDF, without the data:application/pdf;base64, prefix.

filename

Type: string

Required: No

Default Value: merge.pdf

Details: Output PDF filename in the Content-Disposition header. Maximum 255 characters. Allowed characters: A–Z, a–z, 0–9, ., _, and -. Provide the filename with or without the .pdf extension.

contentDisposition

Type: string

Required: No

Default Value: inline

Details: Specifies whether the browser should display or download the PDF.

• "inline": Display the PDF in the browser, if supported.
• "attachment": Prompt a download.

Usage:

{
  "inputs": [
    {"url": "https://pdfbolt.com/samples/merge-sample-1.pdf"},
    {"url": "https://pdfbolt.com/samples/merge-sample-2.pdf"}
  ],
  "filename": "combined-report.pdf",
  "contentDisposition": "attachment"
}

customS3PresignedUrl

Type: string

Required: No

Details: Uploads the merged PDF to your S3-compatible bucket using an HTTPS pre-signed PUT URL. Available only with /v1/tools/merge/sync on paid plans. Maximum 2048 characters.

The URL must remain valid until the upload completes. On success, isCustomS3Bucket is true, and documentUrl and expiresAt are null. Omit this parameter to use PDFBolt's temporary storage.

See Uploading to Your S3 Bucket for setup details.

Usage:

{
  "inputs": [
    {"url": "https://pdfbolt.com/samples/merge-sample-1.pdf"},
    {"url": "https://pdfbolt.com/samples/merge-sample-2.pdf"}
  ],
  "filename": "combined-report.pdf",
  "contentDisposition": "attachment",
  "customS3PresignedUrl": "https://your-bucket.s3.amazonaws.com/combined-report.pdf?<presigned-query-params>"
}

Successful Response

The response format depends on the endpoint.

Direct

Returns HTTP 200 with the merged PDF in the response body.

Content-Type: application/pdf

Save the response body as a PDF file. The result is not stored for later download.

Sync

Returns HTTP 200 with a JSON response containing the result metadata.

Content-Type: application/json

With PDFBolt's default storage, download the PDF from documentUrl before expiresAt (valid for 24 hours). The example below uses default storage.

{
  "requestId": "679bd05f-99ae-49a8-b0b7-eb0d694e284b",
  "status": "SUCCESS",
  "errorCode": null,
  "errorMessage": null,
  "documentUrl": "https://s3.pdfbolt.com/pdfbolt_679bd05f-99ae-49a8-b0b7-eb0d694e284b_2026-11-04T10-00-00Z.pdf",
  "expiresAt": "2026-11-05T10:00:00Z",
  "isAsync": false,
  "duration": 420,
  "documentSizeMb": 0.08,
  "isCustomS3Bucket": false
}

With customS3PresignedUrl, the PDF is uploaded to your bucket. On success, isCustomS3Bucket is true, and documentUrl and expiresAt are null.

See Sync response fields for field descriptions.

Failure Response

If any input fails validation or cannot be downloaded, the entire request fails. No partial PDF is returned and no credits are charged. Check errorCode and errorMessage for details before retrying.

HTTP status	Common cause	Action
400	Invalid parameters, fewer than 2 or more than 20 inputs, an inaccessible URL or PDF download timeout, or an encrypted or invalid PDF.	Check errorMessage and correct the input or settings.
400	Custom S3 upload failed (CUSTOM_S3_UPLOAD_ERROR, Sync only).	Check the pre-signed URL and upload permissions.
413	The combined input PDFs, request body, or output PDF exceeds its size limit.	Reduce the combined file size or request size. See Limits and Credits.
422	Processing exceeded its time limit (CONVERSION_TIMEOUT).	Use smaller or less complex PDFs.

Input errors may include inputs[index] to identify the affected PDF.

Example validation error:

{
  "timestamp": "2026-11-04T10:00:00Z",
  "httpErrorCode": 400,
  "errorCode": "BAD_REQUEST",
  "errorMessage": "Expected 2-20 PDF files."
}

See Error Handling for the error response format and other common errors.

Limits and Credits

Limit	Value
Input files per request	2–20 PDFs
Combined input PDF size	100 MB

Encrypted, empty, and invalid PDFs are rejected. On the Free API plan, the output PDF is limited to 2 MB.

Successful merges cost one credit per started 5 MB of output. Failed operations consume no credits.

Requests share your account's rate limits. The x-pdfbolt-conversion-cost response header reports the credits charged.

Related Documentation

📄️ Compress PDFs

Reduce the size of existing PDF files.

📄️ Convert to PDF/X

Convert existing PDFs to PDF/X-4 or PDF/X-1a.

📄️ OpenAPI Reference

Explore endpoint schemas and response formats.