PDF to PDF API - Go

Join multiple PDF files in Go using the Pdfcrowd API v2. The API is easy to use and the integration takes only a couple of lines of code.

Installation

Install the client library from Github
go get github.com/pdfcrowd/pdfcrowd-go

Learn more about other install options.

Authentication

Authentication is needed in order to use the Pdfcrowd API. The credentials used for accessing the API are your Pdfcrowd username and the API key.
Sign up for a Free Trial

Examples

package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
)

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // configure the conversion
    client.AddPdfFile("/path/to/cover.pdf")
    client.AddPdfFile("/path/to/proposal.pdf")
    client.AddPdfFile("/path/to/price.pdf")
    client.AddPdfFile("/path/to/contact.pdf")

    // run the conversion and write the result to a file
    err := client.ConvertToFile("offer.pdf")

    // check for a conversion error
    handleError(err)
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
)

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // configure the conversion
    client.AddPdfFile("/path/to/cover.pdf")
    client.AddPdfFile("/path/to/proposal.pdf")
    client.AddPdfFile("/path/to/price.pdf")
    client.AddPdfFile("/path/to/contact.pdf")

    // create output file for conversion result
    outputFile, err := os.Create("offer.pdf")

    // check for a file creation error
    handleError(err)

    // close the output file
    defer outputFile.Close()

    // run the conversion and store the result into a pdf variable
    pdf, err := client.Convert()

    // check for a conversion error
    handleError(err)

    // write the pdf into the output file
    _, err = outputFile.Write(pdf)

    // check for a file write error
    handleError(err)
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
)

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // configure the conversion
    client.AddPdfFile("/path/to/cover.pdf")
    client.AddPdfFile("/path/to/proposal.pdf")
    client.AddPdfFile("/path/to/price.pdf")
    client.AddPdfFile("/path/to/contact.pdf")

    // create output stream for conversion result
    outputStream, err := os.Create("offer.pdf")

    // check for a file creation error
    handleError(err)

    // close the output stream
    defer outputStream.Close()

    // run the conversion and write the result into the output stream
    err = client.ConvertToStream(outputStream)

    // check for a conversion error
    handleError(err)
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
    "io/ioutil"
)

func readFile(fileName string) []byte {
    content, err := ioutil.ReadFile(fileName)
    handleError(err)
    return content
}

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // configure the conversion
    client.AddPdfRawData(readFile("/path/to/cover.pdf"))
    client.AddPdfRawData(readFile("/path/to/proposal.pdf"))
    client.AddPdfRawData(readFile("/path/to/price.pdf"))
    client.AddPdfRawData(readFile("/path/to/contact.pdf"))

    // run the conversion and write the result to a file
    err := client.ConvertToFile("offer.pdf")

    // check for a conversion error
    handleError(err)
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
    "io/ioutil"
)

func readFile(fileName string) []byte {
    content, err := ioutil.ReadFile(fileName)
    handleError(err)
    return content
}

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // configure the conversion
    client.AddPdfRawData(readFile("/path/to/cover.pdf"))
    client.AddPdfFile("/path/to/proposal.pdf")
    client.AddPdfRawData(readFile("/path/to/price.pdf"))
    client.AddPdfFile("/path/to/contact.pdf")

    // run the conversion and write the result to a file
    err := client.ConvertToFile("offer.pdf")

    // check for a conversion error
    handleError(err)
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
)

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // configure the conversion
    client.AddPdfFile("/path/to/proposal.pdf")
    client.SetPageWatermark("/path/to/watermark.pdf")

    // run the conversion and write the result to a file
    err := client.ConvertToFile("company_offer.pdf")

    // check for a conversion error
    handleError(err)
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
)

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // configure the conversion
    client.AddPdfFile("/path/to/not_linearized.pdf")
    client.SetLinearize(true)

    // run the conversion and write the result to a file
    err := client.ConvertToFile("linearized.pdf")

    // check for a conversion error
    handleError(err)
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}
package main

import (
    "os"
    "fmt"
    "github.com/pdfcrowd/pdfcrowd-go"
    "io/ioutil"
)

func readFile(fileName string) []byte {
    content, err := ioutil.ReadFile(fileName)
    handleError(err)
    return content
}

func main() {
    // create the API client instance
    client := pdfcrowd.NewPdfToPdfClient("demo", "ce544b6ea52a5621fb9d55f8b542d14d")

    // configure the conversion
    client.SetDebugLog(true)
    client.AddPdfRawData(readFile("/path/to/cover.pdf"))
    client.AddPdfRawData(readFile("/path/to/proposal.pdf"))

    // run the conversion and write the result to a file
    err := client.ConvertToFile("offer.pdf")

    // check for a conversion error
    handleError(err)
    
    // print URL to the debug log
    fmt.Println("Debug log url:", client.GetDebugLogUrl())
    
    // print the number of available conversion credits in your account
    fmt.Println("Remaining credit count:", client.GetRemainingCreditCount())
    
    // print the number of credits consumed by the conversion
    fmt.Println("Consumed credit count:", client.GetConsumedCreditCount())
    
    // print the unique ID of the conversion
    fmt.Println("Job id:", client.GetJobId())
    
    // print the total number of pages in the output document
    fmt.Println("Page count:", client.GetPageCount())
    
    // print the size of the output in bytes
    fmt.Println("Output size:", client.GetOutputSize())
}

func handleError(err error) {
    if err != nil {
        // report the error
        why, ok := err.(pdfcrowd.Error)
        if ok {
            os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))
        } else {
            os.Stderr.WriteString(fmt.Sprintf("Generic Error: %s\n", err))
        }

        // handle the exception here or rethrow and handle it at a higher level
        panic(err.Error())
    }
}

Error Handling

// call the API 

    // print error
    os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error: %s\n", why))

    // print just error code
    os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error Code: %v\n", why.getCode()))

    // print just error message
    os.Stderr.WriteString(fmt.Sprintf("Pdfcrowd Error Message: %v\n", why.getMessage()))

    // or handle the error in your way

Troubleshooting

API Reference - class PdfToPdfClient

Conversion from PDF to PDF. All setter methods return PdfToPdfClient object unless otherwise specified.

Constructor

func NewPdfToPdfClient(userName string, apiKey string) PdfToPdfClient
Constructor for the Pdfcrowd API client.
userName
Your username at Pdfcrowd.
apiKey
Your API key.

 

PDF Manipulation

func (client *PdfToPdfClient) SetAction(action string) *PdfToPdfClient
Specifies the action to be performed on the input PDFs.
action
Allowed values:
  • join
    Concatenate input PDFs into a single one.
  • shuffle
    Collate pages from input PDFs into a single one, take one page at a time from each input PDF. This is useful when combining two scanned documents containing odd and even pages.
Default: join
func (client *PdfToPdfClient) Convert() ([]byte, error)
Perform an action on the input files.
Returns
  • []byte - Byte array containing the output PDF.
func (client *PdfToPdfClient) ConvertToStream(outStream io.Writer) error
Perform an action on the input files and write the output PDF to an output stream.
outStream
The output stream that will contain the output PDF.
func (client *PdfToPdfClient) ConvertToFile(filePath string) error
Perform an action on the input files and write the output PDF to a file.
filePath
The output file path.
The string must not be empty.
func (client *PdfToPdfClient) AddPdfFile(filePath string) *PdfToPdfClient
Add a PDF file to the list of the input PDFs.
filePath
The file path to a local PDF file.
The file must exist and not be empty.
func (client *PdfToPdfClient) AddPdfRawData(pdfRawData []byte) *PdfToPdfClient
Add in-memory raw PDF data to the list of the input PDFs.
Typical usage is for adding PDF created by another Pdfcrowd converter.

Example in PHP:
$clientPdf2Pdf->addPdfRawData($clientHtml2Pdf->convertUrl('http://www.example.com'));
pdfRawData
The raw PDF data.
The input data must be PDF content.

 

Watermark & Background

func (client *PdfToPdfClient) SetPageWatermark(pageWatermark string) *PdfToPdfClient
Apply the first page of the watermark PDF to every page of the output PDF.
pageWatermark
The file path to a local watermark PDF file.
The file must exist and not be empty.
func (client *PdfToPdfClient) SetPageWatermarkUrl(pageWatermarkUrl string) *PdfToPdfClient
Load a watermark PDF from the specified URL and apply the first page of the watermark PDF to every page of the output PDF.
pageWatermarkUrl
The supported protocols are http:// and https://.
Examples:
  • SetPageWatermarkUrl("http://myserver.com/watermark.pdf")
func (client *PdfToPdfClient) SetMultipageWatermark(multipageWatermark string) *PdfToPdfClient
Apply each page of the specified watermark PDF to the corresponding page of the output PDF.
multipageWatermark
The file path to a local watermark PDF file.
The file must exist and not be empty.
func (client *PdfToPdfClient) SetMultipageWatermarkUrl(multipageWatermarkUrl string) *PdfToPdfClient
Load a watermark PDF from the specified URL and apply each page of the specified watermark PDF to the corresponding page of the output PDF.
multipageWatermarkUrl
The supported protocols are http:// and https://.
Examples:
  • SetMultipageWatermarkUrl("http://myserver.com/watermark.pdf")
func (client *PdfToPdfClient) SetPageBackground(pageBackground string) *PdfToPdfClient
Apply the first page of the specified PDF to the background of every page of the output PDF.
pageBackground
The file path to a local background PDF file.
The file must exist and not be empty.
func (client *PdfToPdfClient) SetPageBackgroundUrl(pageBackgroundUrl string) *PdfToPdfClient
Load a background PDF from the specified URL and apply the first page of the background PDF to every page of the output PDF.
pageBackgroundUrl
The supported protocols are http:// and https://.
Examples:
  • SetPageBackgroundUrl("http://myserver.com/background.pdf")
func (client *PdfToPdfClient) SetMultipageBackground(multipageBackground string) *PdfToPdfClient
Apply each page of the specified PDF to the background of the corresponding page of the output PDF.
multipageBackground
The file path to a local background PDF file.
The file must exist and not be empty.
func (client *PdfToPdfClient) SetMultipageBackgroundUrl(multipageBackgroundUrl string) *PdfToPdfClient
Load a background PDF from the specified URL and apply each page of the specified background PDF to the corresponding page of the output PDF.
multipageBackgroundUrl
The supported protocols are http:// and https://.
Examples:
  • SetMultipageBackgroundUrl("http://myserver.com/background.pdf")

 

PDF Format

Miscellaneous values for PDF output.

func (client *PdfToPdfClient) SetLinearize(linearize bool) *PdfToPdfClient
Create linearized PDF. This is also known as Fast Web View.
linearize
Set to true to create linearized PDF.
Default: false
func (client *PdfToPdfClient) SetEncrypt(encrypt bool) *PdfToPdfClient
Encrypt the PDF. This prevents search engines from indexing the contents.
encrypt
Set to true to enable PDF encryption.
Default: false
func (client *PdfToPdfClient) SetUserPassword(userPassword string) *PdfToPdfClient
Protect the PDF with a user password. When a PDF has a user password, it must be supplied in order to view the document and to perform operations allowed by the access permissions.
userPassword
The user password.
func (client *PdfToPdfClient) SetOwnerPassword(ownerPassword string) *PdfToPdfClient
Protect the PDF with an owner password. Supplying an owner password grants unlimited access to the PDF including changing the passwords and access permissions.
ownerPassword
The owner password.
func (client *PdfToPdfClient) SetNoPrint(noPrint bool) *PdfToPdfClient
Disallow printing of the output PDF.
noPrint
Set to true to set the no-print flag in the output PDF.
Default: false
func (client *PdfToPdfClient) SetNoModify(noModify bool) *PdfToPdfClient
Disallow modification of the output PDF.
noModify
Set to true to set the read-only only flag in the output PDF.
Default: false
func (client *PdfToPdfClient) SetNoCopy(noCopy bool) *PdfToPdfClient
Disallow text and graphics extraction from the output PDF.
noCopy
Set to true to set the no-copy flag in the output PDF.
Default: false

 

Viewer Preferences

These preferences specify how a PDF viewer should present the document. The preferences may be ignored by some PDF viewers.

func (client *PdfToPdfClient) SetPageLayout(pageLayout string) *PdfToPdfClient
Specify the page layout to be used when the document is opened.
pageLayout
Allowed values:
  • single-page
    Display one page at a time.
  • one-column
    Display the pages in one column.
  • two-column-left
    Display the pages in two columns, with odd-numbered pages on the left.
  • two-column-right
    Display the pages in two columns, with odd-numbered pages on the right.
func (client *PdfToPdfClient) SetPageMode(pageMode string) *PdfToPdfClient
Specify how the document should be displayed when opened.
pageMode
Allowed values:
  • full-screen
    Full-screen mode.
  • thumbnails
    Thumbnail images are visible.
  • outlines
    Document outline is visible.
func (client *PdfToPdfClient) SetInitialZoomType(initialZoomType string) *PdfToPdfClient
Specify how the page should be displayed when opened.
initialZoomType
Allowed values:
  • fit-width
    The page content is magnified just enough to fit the entire width of the page within the window.
  • fit-height
    The page content is magnified just enough to fit the entire height of the page within the window.
  • fit-page
    The page content is magnified just enough to fit the entire page within the window both horizontally and vertically. If the required horizontal and vertical magnification factors are different, use the smaller of the two, centering the page within the window in the other dimension.
func (client *PdfToPdfClient) SetInitialPage(initialPage int) *PdfToPdfClient
Display the specified page when the document is opened.
initialPage
Must be a positive integer number.
func (client *PdfToPdfClient) SetInitialZoom(initialZoom int) *PdfToPdfClient
Specify the initial page zoom in percents when the document is opened.
initialZoom
Must be a positive integer number.
func (client *PdfToPdfClient) SetHideToolbar(hideToolbar bool) *PdfToPdfClient
Specify whether to hide the viewer application's tool bars when the document is active.
hideToolbar
Set to true to hide tool bars.
Default: false
func (client *PdfToPdfClient) SetHideMenubar(hideMenubar bool) *PdfToPdfClient
Specify whether to hide the viewer application's menu bar when the document is active.
hideMenubar
Set to true to hide the menu bar.
Default: false
func (client *PdfToPdfClient) SetHideWindowUi(hideWindowUi bool) *PdfToPdfClient
Specify whether to hide user interface elements in the document's window (such as scroll bars and navigation controls), leaving only the document's contents displayed.
hideWindowUi
Set to true to hide ui elements.
Default: false
func (client *PdfToPdfClient) SetFitWindow(fitWindow bool) *PdfToPdfClient
Specify whether to resize the document's window to fit the size of the first displayed page.
fitWindow
Set to true to resize the window.
Default: false
func (client *PdfToPdfClient) SetCenterWindow(centerWindow bool) *PdfToPdfClient
Specify whether to position the document's window in the center of the screen.
centerWindow
Set to true to center the window.
Default: false
func (client *PdfToPdfClient) SetDisplayTitle(displayTitle bool) *PdfToPdfClient
Specify whether the window's title bar should display the document title. If false , the title bar should instead display the name of the PDF file containing the document.
displayTitle
Set to true to display the title.
Default: false
func (client *PdfToPdfClient) SetRightToLeft(rightToLeft bool) *PdfToPdfClient
Set the predominant reading order for text to right-to-left. This option has no direct effect on the document's contents or page numbering but can be used to determine the relative positioning of pages when displayed side by side or printed n-up
rightToLeft
Set to true to set right-to-left reading order.
Default: false

 

Miscellaneous

func (client *PdfToPdfClient) SetDebugLog(debugLog bool) *PdfToPdfClient
Turn on the debug logging. Details about the conversion are stored in the debug log. The URL of the log can be obtained from the getDebugLogUrl method or available in conversion statistics.
debugLog
Set to true to enable the debug logging.
Default: false
func (client *PdfToPdfClient) GetDebugLogUrl() string
Get the URL of the debug log for the last conversion.
Returns
  • string - The link to the debug log.
func (client *PdfToPdfClient) GetRemainingCreditCount() int
Get the number of conversion credits available in your account.
This method can only be called after a call to one of the convertXYZ methods.
The returned value can differ from the actual count if you run parallel conversions.
The special value 999999 is returned if the information is not available.
Returns
  • int - The number of credits.
func (client *PdfToPdfClient) GetConsumedCreditCount() int
Get the number of credits consumed by the last conversion.
Returns
  • int - The number of credits.
func (client *PdfToPdfClient) GetJobId() string
Get the job id.
Returns
  • string - The unique job identifier.
func (client *PdfToPdfClient) GetPageCount() int
Get the total number of pages in the output document.
Returns
  • int - The page count.
func (client *PdfToPdfClient) GetOutputSize() int
Get the size of the output in bytes.
Returns
  • int - The count of bytes.
func (client *PdfToPdfClient) SetTag(tag string) *PdfToPdfClient
Tag the conversion with a custom value. The tag is used in conversion statistics. A value longer than 32 characters is cut off.
tag
A string with the custom tag.

 

API Client Options

func (client *PdfToPdfClient) SetUseHttp(useHttp bool) *PdfToPdfClient
Specifies if the client communicates over HTTP or HTTPS with Pdfcrowd API.
useHttp
Set to true to use HTTP.
Default: false
func (client *PdfToPdfClient) SetUserAgent(userAgent string) *PdfToPdfClient
Set a custom user agent HTTP header. It can be usefull if you are behind some proxy or firewall.
userAgent
The user agent string.
Default: pdfcrowd_go_client/4.11.0 (http://pdfcrowd.com)
func (client *PdfToPdfClient) SetProxy(host string, port int, userName string, password string) *PdfToPdfClient
Specifies an HTTP proxy that the API client library will use to connect to the internet.
host
The proxy hostname.
port
The proxy port.
userName
The username.
password
The password.
func (client *PdfToPdfClient) SetRetryCount(retryCount int) *PdfToPdfClient
Specifies the number of retries when the 502 HTTP status code is received. The 502 status code indicates a temporary network issue. This feature can be disabled by setting to 0.
retryCount
Number of retries wanted.
Default: 1