Frequently Asked Questions

Licensing and Open Source

What is the license for Aspose.PDF FOSS for Go?

Aspose.PDF FOSS for Go is released under the MIT License. The full license text is included in the repository at github.com/aspose-pdf-foss/aspose-pdf-foss-for-go. No registration, activation file, or runtime key is required.

Can I use Aspose.PDF FOSS for Go in a commercial product?

Yes. The MIT license permits unrestricted commercial use, modification, distribution, and private use. You must include the copyright notice and MIT license text in all copies or substantial portions of the software.

Is there an enterprise version?

Aspose.PDF FOSS is the open-source, MIT-licensed edition. A separate commercial Aspose.PDF product is available as the Aspose.PDF — Enterprise Product Family with enterprise support, extended format coverage, and cloud integration.

Installation and Requirements

How do I install Aspose.PDF FOSS for Go?

Add the module to your Go project:

go get github.com/aspose-pdf-foss/aspose-pdf-foss-for-go

Import it with an alias in your source files:

import pdf "github.com/aspose-pdf-foss/aspose-pdf-foss-for-go"

What Go version is required?

Go 1.24 or later is required. Verify your version with go version.

Are there native or system library dependencies?

No. Aspose.PDF FOSS for Go is a pure-Go implementation with no C, C++, or CGo dependencies. It does not require any system libraries, PDF viewers, or external tools.

API Usage

How do I open an existing PDF?

Use pdf.Open for standard PDFs and pdf.OpenWithPassword for password-protected files:

doc, err := pdf.Open("document.pdf")
if err != nil {
    panic(err)
}
fmt.Println(doc.PageCount())

How do I split a PDF into individual pages?

Document.Split returns a []*Document, one per page:

doc, _ := pdf.Open("report.pdf")
pages, _ := doc.Split()
for i, p := range pages {
    p.Save(fmt.Sprintf("page_%03d.pdf", i+1))
}

How do I merge multiple PDFs?

Document.Append merges a source document in-place:

base, _ := pdf.Open("part1.pdf")
part2, _ := pdf.Open("part2.pdf")
base.Append(part2)
base.Save("combined.pdf")

How do I fill an AcroForm field?

Use Document.Form().Field(name) and assert the concrete type:

doc, _ := pdf.Open("form.pdf")
text := doc.Form().Field("customer_name").(*pdf.TextBoxField)
text.SetValue("Jane Doe")

check := doc.Form().Field("agree").(*pdf.CheckboxField)
check.SetChecked(true)

doc.Save("form_filled.pdf")

Supported field types: TextBoxField, CheckboxField, RadioButtonField, ComboBoxField, ListBoxField, ButtonField.

How do I add bookmarks?

Create an OutlineItemCollection and set a Destination:

doc, _ := pdf.Open("manual.pdf")
page, _ := doc.Page(1)

bm := pdf.NewOutlineItemCollection(doc)
bm.SetTitle("Chapter 1")
bm.SetDestination(pdf.NewDestinationXYZ(page, 0, 800, 1.0))
doc.Outlines().Add(bm)
doc.Save("manual_with_bookmarks.pdf")

Security and Encryption

How do I password-protect a PDF?

Use Document.SetEncryption with an EncryptionOptions struct to apply password protection and permission flags. Provide a user password for opening the file and an owner password for modification rights:

doc, _ := pdf.Open("doc.pdf")
doc.SetEncryption(pdf.EncryptionOptions{
    UserPassword:  "userpass",
    OwnerPassword: "ownerpass",
    Permissions:   &pdf.Permissions{AllowPrint: true, AllowCopy: false},
})
doc.Save("doc_protected.pdf")

Which encryption algorithms are supported?

Three algorithms are available via EncryptionOptions.Algorithm:

How do I open a password-protected file?

Use pdf.OpenWithPassword when the file requires authentication. Pass the user password as the second argument; it returns a normal *Document once decryption succeeds:

doc, err := pdf.OpenWithPassword("protected.pdf", "userpass")
if err != nil {
    panic(err)
}
fmt.Println(doc.PageCount())

How do I remove encryption from a PDF?

Call Document.RemoveEncryption after opening the file with the correct password. Save the result to write an unencrypted copy:

doc, _ := pdf.OpenWithPassword("protected.pdf", "userpass")
doc.RemoveEncryption()
doc.Save("decrypted.pdf")

Rendering and Text

How do I render a PDF page to an image?

Use one of the device types: BmpDevice, PngDevice, JpegDevice, TiffDevice, or GifDevice. Construct the device with a Resolution value and call the corresponding Render* method with an io.Writer and RenderOptions:

doc, _ := pdf.Open("report.pdf")
page, _ := doc.Page(1)
f, _ := os.Create("page1.png")
defer f.Close()
page.RenderPNG(f, pdf.RenderOptions{DPI: 150})

How do I search for text in a PDF?

Call Document.SearchText with a query string and SearchOptions. The result is a slice of TextMatch values — each carries the matched text, its page index, and its bounding box.

doc, _ := pdf.Open("doc.pdf")
matches, _ := doc.SearchText("total", pdf.SearchOptions{CaseInsensitive: true})
for _, m := range matches {
    fmt.Printf("page %d: %q\n", m.PageNumber, m.Text)
}

How do I flatten a form?

Call Document.Flatten after filling or reviewing a form. The method bakes all field values into the page graphics and removes the interactive form fields:

doc, _ := pdf.Open("filled.pdf")
doc.Flatten()
doc.Save("flat.pdf")

Known Limitations

Are all PDF features supported?

The library covers the most common document management operations: open, create, save, split, merge, page extraction, encryption, AcroForms, tables, bookmarks, annotations, rendering to image, text search, and form flattening. Advanced features such as digital signatures, 3D content, and PDF/A conversion may not be fully implemented in the current release. Check the repository README for the current feature status.

What happens if I use a field type assertion that does not match?

A type assertion on Field that does not match the actual field type will panic. Use pdf.FieldType(f) to inspect the type before asserting, or use a type switch:

doc, _ := pdf.Open("form.pdf")
for _, f := range doc.Form().Fields() {
    switch v := f.(type) {
    case *pdf.TextBoxField:
        fmt.Println("text:", v.Value())
    case *pdf.CheckboxField:
        fmt.Println("checked:", v.Checked())
    }
}