--- title: "onepdf articles" url: https://recursiveai.org/onepdf/articles/ description: "Guides to working with OnePDF: how-tos, migrations and comparisons." --- # onepdf articles Guides to working with OnePDF: how-tos, migrations and comparisons. - [QuestPDF license: who can use it free, and what it costs](https://recursiveai.org/onepdf/articles/questpdf-license/) (October 27, 2026): QuestPDF’s Community License is free below USD 1M revenue; Professional is $1,999 and Enterprise $4,999. The terms, the MIT versions and alternatives. - [Migrating from PDFsharp and MigraDoc to OnePDF](https://recursiveai.org/onepdf/articles/migrate-from-pdfsharp/) (October 27, 2026): Move C# code from PDFsharp and MigraDoc 6.x to OnePDF: MigraDoc documents to OnePdf.Layout, XGraphics to the content builder, samples run on both libraries. - [Migrating from PdfPig to OnePDF](https://recursiveai.org/onepdf/articles/migrate-from-pdfpig/) (October 27, 2026): Move C# code from PdfPig 0.1.16 to OnePDF: what changes, samples run on both libraries, and the difference for text order, images, merging and editing. - [Extract images from a PDF in C#](https://recursiveai.org/onepdf/articles/extract-images-from-pdf-csharp/) (October 27, 2026): Extract images from PDF files in C#: save JPEGs byte for byte, write the rest as PNG with transparency, and handle JPEG 2000 and CMYK, with tested code. - [Split a PDF in C#](https://recursiveai.org/onepdf/articles/split-pdf-csharp/) (October 26, 2026): Split a PDF in C# into single pages, fixed-size parts, page ranges or one file per bookmark, keeping bookmarks, links and form fields. Pure .NET, MIT or Apache-2.0. - [Digitally sign a PDF in C#](https://recursiveai.org/onepdf/articles/sign-pdf-csharp/) (October 26, 2026): Sign a PDF in C# with a .pfx certificate: PAdES B-B and B-T, visible or certification signatures, HSM and cloud keys, and verification that catches changes. - [Redact a PDF in C#](https://recursiveai.org/onepdf/articles/redact-pdf-csharp/) (October 26, 2026): Redact PDFs in C# so the text is really gone: find names and numbers, remove them from the page content, blank image areas, clean metadata, and check the result. - [PDFsharp license: what changed in 6.5.0](https://recursiveai.org/onepdf/articles/pdfsharp-license/) (October 26, 2026): PDFsharp and MigraDoc 6.5.0 are AGPL or a €750 commercial license, and 6.2.4 and earlier stay MIT. What changed, the license exception, and MIT alternatives. - [Create PDF/UA documents in C#](https://recursiveai.org/onepdf/articles/pdf-ua-csharp/) (October 26, 2026): Create PDF/UA-1 and PDF/UA-2 files in C#: tagged headings, tables, lists and alt text, PDF/A-2a in the same file, tagging existing PDFs, and checks that list every violation. - [Migrating from iText 7 and iTextSharp to OnePDF](https://recursiveai.org/onepdf/articles/migrate-from-itext/) (October 26, 2026): Move C# code from iText 7, 8 or 9 (and iTextSharp) to OnePDF: the API map, side-by-side samples run on both libraries, and what has no equivalent. - [Merge PDF files in C#](https://recursiveai.org/onepdf/articles/merge-pdf-csharp/) (October 26, 2026): Merge PDF files in C# with OnePDF: files, byte arrays and ASP.NET Core uploads, chosen pages, and bookmarks, links and form fields kept. MIT or Apache-2.0. - [iText license: AGPL, commercial and what it costs](https://recursiveai.org/onepdf/articles/itext-license/) (October 26, 2026): What an iText license costs and what the free AGPL version requires, from iText’s pages: quote-only pricing, iText 9, iTextSharp and permissive alternatives. - [Flatten a PDF form in C#](https://recursiveai.org/onepdf/articles/flatten-pdf-csharp/) (October 26, 2026): Flatten PDF forms in C# with OnePDF: bake filled values into the page, flatten chosen fields, drop on-screen buttons and check the result. MIT or Apache-2.0. - [Fill PDF form fields in C#](https://recursiveai.org/onepdf/articles/fill-pdf-form-csharp/) (October 26, 2026): Fill PDF form fields in C# with OnePDF: read field names, set text, check boxes, radio buttons and lists, catch bad values, then flatten. MIT or Apache-2.0. - [Extract text from a PDF in C#](https://recursiveai.org/onepdf/articles/extract-text-from-pdf-csharp/) (October 26, 2026): Extract text from PDF files in C# with OnePDF: every page in reading order, two-column pages, words with positions, uploads and passwords. MIT or Apache-2.0. - [Choosing a C# PDF library](https://recursiveai.org/onepdf/articles/csharp-pdf-library/) (October 26, 2026): C# PDF libraries compared by license, price and job: OnePDF, PdfPig, PDFsharp, QuestPDF, iText, IronPDF, Aspose.PDF and Syncfusion, with every term sourced. - [Create a PDF in C#](https://recursiveai.org/onepdf/articles/create-pdf-csharp/) (October 26, 2026): Create PDF files in C# from code with OnePdf.Layout: text, tables that break across pages, SVG logos, page X of Y, ASP.NET Core downloads and PDF/A. No HTML. - [Create PDF/A in C#](https://recursiveai.org/onepdf/articles/create-pdf-a-csharp/) (October 26, 2026): Create PDF/A-2 and PDF/A-3 files in C# from documents you generate or edit, attach XML data to PDF/A-3, and check any PDF. Limits first: it doesn’t convert arbitrary files. - [Arabic and Hindi text in a C# PDF](https://recursiveai.org/onepdf/articles/arabic-text-pdf-csharp/) (October 26, 2026): Why Arabic comes out unjoined and Hindi broken in C# PDFs, and how to fix it: shaped text, right-to-left layout and font fallback with OnePdf.Layout. MIT or Apache-2.0. - [Add an image or watermark to a PDF in C#](https://recursiveai.org/onepdf/articles/add-image-to-pdf-csharp/) (October 26, 2026): Add a PNG or JPEG to an existing PDF in C#, stamp a text or image watermark on every page, and write text onto pages, with pure .NET code. MIT or Apache-2.0.