IronPDF

replacing existing text in PDF documents with the IronPDF .NET library, where the official Replace Text in PDF how-to says the replace text action can be applied to any PdfDocument object whether newly rendered or imported, using ReplaceTextOnAllPages with the old and the new text, ReplaceTextOnPage for a single page and ReplaceTextOnPages for multiple specified pages, with zero based page indexes, support for newline characters in the replacement text and an optional custom font and size on the page method, raising an exception when the old text cannot be found, and saving the edited PDF to a new file, with the page showing version 2026.10

converting other formats into PDF and PDF pages into other formats with the IronPDF .NET library, where the official how-to guides document DOCX to PDF through the DocxToPdfRenderer class and RenderDocxAsPdf taking a file path, a byte array or a stream with DocxPdfRenderOptions for mail merge and page setup, image to PDF for single or multiple JPG, PNG or TIFF images through ImageToPdfConverter.ImageToPdf with customizable placement, and further official guides for HTML file, HTML string, HTML element, HTML zip, ASPX, JavaScript, Markdown, RTF, URL and XML to PDF, and document PDF to HTML through the SaveAsHtml method, PDF to SVG through the PdfToSvg namespace converting page by page, and rasterizing PDF pages into PNG, JPEG or TIFF image files through RasterizeToImageFiles

protecting PDF documents with passwords and permissions using the IronPDF .NET library, where the official Passwords and Permissions guide documents a user password, also called the open password, which is required to open and view the document, and an owner password, also called the permissions password, which controls permissions for editing, printing and other actions, set through the SecuritySettings UserPassword and OwnerPassword properties, with permissions that can make a document unprintable, read-only and encrypted, an EncryptionType setting whose values are Rc4_128 for 128 bit RC4 as the default, Aes_128 for 128 bit AES and Aes_256 for 256 bit AES, each listed with the PDF version and minimum Acrobat reader it requires, a note that RC4 remains the default so existing code is unaffected but is cryptographically weak and that AES is recommended for new documents, and opening a protected document through PdfDocument FromFile with a password that the library detects as user or owner and uses to grant the corresponding access level

signing PDF documents with the IronPDF .NET library, where the official Signing PDF Documents guide distinguishes three separate things, applying a certificate based digital signature with an X509Certificate2 certificate, stamping a visual handwritten signature image onto a document, and adding an interactive form field for users to sign electronically, where the HSM guide documents signing through the PKCS#11 API with a UsbPkcs11HsmSigner built from the library path, a PIN, a token label and a key label so that private keys stay on the device, and where the Verify PDF Signatures guide documents reading verified signatures through PdfDocument GetVerifiedSignatures, which returns VerifiedSignature objects whose SignerCertificate and CertificateChain properties expose the signer X.509 identity, the issuing CA, validity dates, a SHA 256 thumbprint, the raw DER bytes and the intermediate certificates up to the root

merging PDF documents with the IronPDF .NET library, where the official How to Merge or Split PDFs guide says IronPDF merges multiple PDF files into one document using the Merge method, and its quickstart merges two documents loaded with PdfDocument FromFile into a single document that is saved with SaveAs, with the inputs documented as existing PDFs or PDFs rendered from an HTML string, file or URL, and with the guide stating no ordering, bookmark or metadata preservation behaviour for the merged output

reducing PDF file size through the PdfDocument compression API, which re-encodes embedded images as JPEG at a chosen quality and can strip the PDF structure tree; not lossless compression and no guaranteed size reduction

exporting PDF documents to the PDF/UA accessibility standard with the IronPDF .NET library, where the official Export PDF/UA Documents guide says PDFs are exported using the SaveAsPdfUA method on a PdfDocument, or built with RenderHtmlAsPdfUA straight from HTML, that the library writes both PDF/UA-1 (ISO 14289-1) and PDF/UA-2 (ISO 14289-2:2024) while tagging the document so screen readers and other assistive technologies can read it, that PDF/UA defines how a PDF carries its structure through a tagged content tree, alternative text for images, a declared reading order and a document language, that an existing PDF can be loaded and converted to the standard in one call, and that examples produce PDF/UA-1 by default while PDF/UA-2 is written using a version parameter