Enterprise PDF for C# / .NET

The C# PDF library
.NET deserves.

Q: Does this C# PDF library do HTML-to-PDF?

No, and that is deliberate. rust-pdf renders PDFs natively from a C# document model instead of driving a headless Chromium browser. That keeps memory use low, output deterministic, and PDF/A and PDF/UA conformance precise, which a browser print path cannot guarantee.

Q: Is the C# PDF library free?

Everyday PDF generation (pages, text, fonts, images, tables, merge and split) is free forever, as are PDF/A archival, signatures and PAdES, AES-256 encryption and PDF/UA accessibility.

Q: Does it need a browser, JVM or any runtime besides .NET?

No. It is a native Rust core shipped per-runtime inside the NuGet package and called through source-generated P/Invoke. There is no Chromium process, no JVM and nothing to compile, just dotnet add package RustPdf.

Q: Is it AGPL like iTextSharp / iText?

No. rust-pdf uses MIT licensed, never the AGPL of iText or the per-server billing of Aspose. You can ship it inside a closed-source product without opening your own source.

Q: Which .NET versions are supported?

rust-pdf targets .NET 8 and later on Linux, macOS and Windows, including server, container and Native AOT deployments. The native core runs in-process on your own infrastructure.

rust-pdf is a C# PDF library that generates archival PDF/A, signs documents with PAdES, encrypts with AES-256 and produces accessible PDF/UA from idiomatic C#. One memory-safe core, the same behavior as every other binding, running entirely on your servers: no per-document SaaS fees, no data leaving your network, no AGPL strings.

Install from NuGet. The native core ships per-runtime, nothing to compile.

dotnet add package RustPdf

Start free · .NET Read the docs

Validated by independent tools: veraPDFpdfsigopenssl cmsqpdfmutool

Why .NET teams pick rust-pdf

.NET runs the back office of banks, insurers and the public sector, exactly where PDF/A archival, qualified signatures, AES-256 and PDF/UA are mandatory. Yet the established options are an AGPL library you can't ship without opening your source, a per-server commercial bill, or a SaaS that uploads your documents.

rust-pdf is one dotnet add package with source-generated P/Invoke, a clean Document / EditableDoc API, with every feature free. The native core is Send, so each request renders on its own handle with no GC pauses.

Native, not headless Chrome: no browser process, no gigabytes of RAM per worker.
Runs on your servers: documents never leave your network and nothing phones home, ideal for LGPD/GDPR, fintech and health.
No AGPL trap: MIT licensed, never the AGPL of iText or the per-server billing of Aspose.
Deterministic output: the same input always produces the same bytes, so you can diff and audit it.
Free to build with: every feature is free forever.

Create your first PDF in C# in five lines

Add the package and you have a working Document. No services to register, no browser to install. Generation is free, forever.

// dotnet add package RustPdf
using RustPdf;

using var doc = new Document();
int font = doc.AddFontFile("Roboto-Regular.ttf");
doc.AddPage();
doc.ShowText(font, 26, 72, 760, "Hello from C#");
doc.Save("hello.pdf");        // done — a valid PDF on disk

Sign PDFs with PAdES B-B · B-LT · B-LTA

A real PKCS#7/CMS detached signature, applied as an incremental update so the original bytes stay byte-for-byte intact. Build up the long-term validation chain one level at a time.

`B-B` · baseline

The signature itself: hashes the byte range, embeds the CMS with the signing certificate and the ESS signing-certificate-v2 attribute.

`B-LT` · long-term

Adds a Document Security Store (/DSS) carrying the certificates and CRLs needed to validate the signature years later, offline.

`B-LTA` · archival

Adds an RFC 3161 document timestamp (/DocTimeStamp) over the DSS, so the whole package can be re-validated after the certificates expire.

using RustPdf;

byte[] pdf  = new Document().AddPage().Save();
byte[] key  = File.ReadAllBytes("signer-key.der");
byte[] cert = File.ReadAllBytes("signer-cert.der");

// B-B: a PAdES baseline signature
byte[] signed = Pdf.Sign(pdf, key, cert, reason: "Approved", pades: true);

// B-LT: embed the validation material, then B-LTA: timestamp it
byte[] lt   = Pdf.AddDss(signed, certs: new[] { cert });
byte[] lta  = Pdf.Timestamp(lt, tsaKey, tsaCert);
File.WriteAllBytes("contract.pdf", lta);

Every signature is verified in CI with pdfsig and openssl cms. Read the full flow on the PAdES page.

Archival PDF/A, levels 1b through 3a

One call switches a document to an ISO 19005 archival profile: an embedded sRGB ICC profile, an output intent, synchronized XMP metadata and a conformance-correct structure. Pick the level your regulator asks for.

Level	Profile	Use it when
1b	PDF/A-1b	Legacy mandates pinned to PDF 1.4 (forces a `/CIDSet` per font, no object streams).
2b	PDF/A-2b	The modern default for visual archival: object streams, JPEG2000, transparency.
2a	PDF/A-2a	Everything in 2b plus a tagged logical structure, so it doubles as PDF/UA.
3b / 3a	PDF/A-3	Lets you attach the source file (e.g. the original XML invoice) inside the archive.

using var doc = new Document();
doc.Pdfa(PdfaLevel.A2a)               // archival + tagged in one builder
   .Tagged()
   .SetInfo(title: "Q3 Report");
int f = doc.AddFontFile("Roboto-Regular.ttf");
doc.AddPage();
doc.ShowText(f, 26, 72, 760, "Annual report", headingLevel: 1);
byte[] bytes = doc.ToBytes();         // veraPDF-clean PDF/A-2a

rust-pdf produces and validates 1b, 2b, 2a, 3b, 3a and 4. Read the PDF/A page for what each level guarantees.

Encrypt with AES-256 (R6)

Apply standard security-handler encryption with a user and/or owner password. The file key and IVs come from the OS CSPRNG, so every output is unique. RC4 and AES-128 are there too for legacy readers.

using var ed = EditableDoc.Load(bytes);
ed.Encrypt(owner: "owner-secret", method: Encryption.Aes256);
ed.Save("secured.pdf");               // qpdf-verified AES-256

More on the cipher and key derivation on the AES-256 page.

Accessible, tagged PDF/UA-1

Accessibility here means a real structure tree. rust-pdf builds a nested tree of semantic tags so screen readers and ISO 14289-1 (PDF/UA) validators see a genuine document, not a flat canvas.

Headings H1–H6 with a correct reading order and nesting.
Figures with /Alt text; decorative art marked as /Artifact.
Tables with header scope and cell-to-header associations.
Lists (/L · /LI · /LBody) and captions.
/Lang, /MarkInfo and DisplayDocTitle set for you.

Validated against PDF/UA-1 with veraPDF. See the PDF/UA page.

No Chromium. No JVM. No AGPL.

The big C# PDF libraries make you choose between a heavyweight browser dependency, an open-source license that forces your code open, or a metered bill. rust-pdf is a single native package, MIT licensed and free.

	rust-pdf	IronPDF	iText 7	QuestPDF
Engine	Native Rust core	Chromium	Java/.NET	.NET (SkiaSharp)
Heavy runtime dependency	None	Chromium	—	None
License to ship closed source	MIT, free	Commercial	AGPL or paid	Free <$1M, else paid
Per-document / metered fees	No	No	No	No
Runs fully offline	Yes	Yes	Yes	Yes
PDF/A 1b–3a + A-4/4e/4f	Yes	Partial	Yes	No
PAdES B-B/B-LT/B-LTA	Yes	Basic	Yes	No
PDF/UA tagged structure	Yes	Yes	Yes	No
Same engine in other languages	8 bindings	.NET only	Java/.NET	.NET only

Comparison reflects publicly documented behavior at time of writing; verify against each vendor's current docs for your use case.

Every feature is free.

Prototype and ship everyday PDFs for free. PDF/A, signatures, encryption and accessibility are all included in .NET and every other binding.

Core free

Pages & vector graphics
Embedded/subset fonts, Unicode shaping
Justified paragraphs & tables
Images (JPEG/PNG/alpha/16-bit)
Merge / split / rotate
Text extraction & optimize

Advanced free

PDF/A: 1b / 2b / 2a / 3b / 3a archival
Digital signatures: PKCS#7, visible & multiple
PAdES: B-B / B-LT / B-LTA + RFC 3161 timestamps
Encryption: RC4 / AES-128 / AES-256 (R6)
Accessibility: Tagged PDF / PDF/UA-1
AcroForm: fields with generated appearances
Validate & convert: verify signatures, PDF→PDF/A, ZUGFeRD/Factur-X
Process: redaction, image extraction, form fill/flatten, page→PNG

Every feature is free.

rust-pdf is MIT licensed — PDF/A, digital signatures, encryption, accessibility and page rendering are all included. No key, no account, no card.

One engine. Eight languages. Identical bytes.

The C# package wraps the exact same Rust core as every other binding, so a PDF generated from .NET is byte-identical to one generated from Python or Go. Standardize one document pipeline across your whole stack,

Python Go Node.js PHP Ruby Swift Delphi All languages

Start building in .NET

One Rust core, the same output in every language — free and MIT licensed.

Start free · .NET Read the docs

C# PDF library FAQ

Does this C# PDF library do HTML-to-PDF?

No, and that's deliberate. rust-pdf renders PDFs natively from a C# document model instead of driving a headless Chromium browser. That keeps memory use low, output deterministic, and PDF/A and PDF/UA conformance precise, guarantees a browser print path can't make. If your input is HTML, render it server-side first and place the result; if it's structured data, build it directly with the API.

Is the C# PDF library free?

Everyday PDF generation (pages, text, fonts, images, tables, merge and split) is free forever, as are PDF/A archival, signatures and PAdES, AES-256 encryption and PDF/UA accessibility.

Does it need a browser, JVM or any runtime besides .NET?

No. It's a native Rust core shipped per-runtime inside the NuGet package and called through source-generated P/Invoke. There's no Chromium process, no JVM and nothing to compile, just dotnet add package RustPdf.

Is it AGPL like iTextSharp / iText?

No. rust-pdf uses MIT licensed, never the AGPL of iText or the per-server billing of Aspose. You can ship it inside a closed-source product without opening your own source.

Which .NET versions are supported?

rust-pdf targets .NET 8 and later on Linux, macOS and Windows, including server, container and Native AOT deployments. The native core runs in-process on your own infrastructure.

How is the output validated?

Independently: veraPDF (PDF/A 1b–3a + A-4/4e/4f and PDF/UA-1), pdfsig and openssl cms for signatures, and qpdf/mutool for structure, all in CI, not "conformance marketing".

The C# PDF library.NET deserves.

Why .NET teams pick rust-pdf

Create your first PDF in C# in five lines

Sign PDFs with PAdES B-B · B-LT · B-LTA

B-B · baseline

B-LT · long-term

B-LTA · archival

Archival PDF/A, levels 1b through 3a

Encrypt with AES-256 (R6)

Accessible, tagged PDF/UA-1

No Chromium. No JVM. No AGPL.

Every feature is free.

Core free

Advanced free

Every feature is free.

One engine. Eight languages. Identical bytes.

Start building in .NET

C# PDF library FAQ

The C# PDF library
.NET deserves.

`B-B` · baseline

`B-LT` · long-term

`B-LTA` · archival