miPDFlib compared with iText and Syncfusion PDF

A short, practical comparison for the tasks that matter in form and signing projects. It is not a benchmark. A detailed version with background and examples is the article iText or Syncfusion PDF? A practical comparison for forms and digital signatures in .NET (German). For switching code over, see the migration guide.

iText and Syncfusion PDF are mature, widely used libraries with a much larger feature set and commercial support. miPDFlib is young; its strengths are the licence, signatures without BouncyCastle and archiving formats.

Licence

iText Syncfusion PDF miPDFlib
Licence AGPLv3 or commercial commercial; free Community License for small companies (revenue, team and capital limits) Apache-2.0
Closed commercial product commercial licence required commercial licence, or Community License within its limits allowed, free of charge
Obligations AGPL: disclose the source of your application; producer line in every PDF licence key registration, otherwise a trial watermark keep LICENSE and NOTICE when redistributing
Commercial support yes yes no

PDF handling

iText Syncfusion PDF miPDFlib
Incremental saving StampingProperties.UseAppendMode() PdfFileStructure.IncrementalUpdate = true new PdfSaveOptions { Incremental = true }; signing is always incremental
Office documents to PDF – in the same suite – (recommended: LibreOffice via Gotenberg, see README)

Forms (AcroForms)

Task iText Syncfusion PDF miPDFlib
Load the form PdfAcroForm.GetAcroForm(doc, …) PdfLoadedDocument.Form doc.GetForm()
Read fields GetAllFormFields() typed classes such as PdfLoadedTextBoxField form.Fields, typed via GetField<PdfTextField>("name")
Create fields builder classes, e.g. TextFormFieldBuilder a class per field type, e.g. PdfTextBoxField form.AddTextField(..), AddCheckBox(..), AddSignatureField(..)
Flatten via the AcroForm object Flatten = true / FlattenFields() form.Flatten()
Data exchange field API additionally FDF import/export form.GetValues(), FDF and XFDF import/export, XFA data

Digital signatures

Topic iText Syncfusion PDF miPDFlib
Signing PdfSigner, CMS or CAdES PdfSignature, CMS or CAdES PdfSigner.Sign, CMS or CAdES (default: PAdES)
PAdES levels PdfPadesSigner: B, T, LT, LTA timestamps, LTV, archive timestamps B-B, B-T; B-LT and B-LTA via PdfLtv
External signing (HSM, cloud) IExternalSignature, IExternalSignatureContainer ComputeHash event, IPdfExternalSigner IExternalSigner; two-step PrepareExternalSignature / CompleteExternalSignature
Custom signed attributes via your own CMS container via ComputeHash and your own CMS AdditionalSignedAttributes
Certification and field locks DocMDP, FieldMDP DocMDP DocMDP (Certification), FieldMDP (FieldLock)
Validation validation module (since 9) built in PdfSignatureValidator (integrity, chain, coverage, timestamp, PAdES level, field locks, revocation status from the embedded OCSP responses and CRLs)
Cryptography BouncyCastle (mandatory adapter) own implementation; BouncyCastle or .NET for custom CMS .NET (System.Security.Cryptography.Pkcs), no BouncyCastle

When to choose what

  • Open-source project under the AGPL: iText – mature, with very comprehensive signature support.
  • Closed product of a small company within the Community License limits: Syncfusion PDF.
  • Office conversion in the same workflow: Syncfusion.
  • Commercial support, FIPS or the widest feature set: iText or Syncfusion with a commercial licence.
  • Closed product without licence costs and without revenue or size limits, focused on forms, PAdES signatures, PDF/A, PDF/UA or e-invoices: miPDFlib – test it with your own documents before going live.

Information on iText and Syncfusion as of October 2026, from the vendors' documentation; the binding licence terms are those of the vendors.

Edit this page