TinyPdf C#

📖 Read the Deep-Dive: I built a minimal zero-dependency PDF library for C# because I hate bloat.

A minimal PDF creation library for .NET 10, ported from the original tinypdf by Lulzx.

Features

• 1041 lines of code
• Zero external dependencies
• Text rendering (Helvetica, Times, Courier) with alignment support
• Clickable links with optional underlining
• Shapes (Rectangles, Lines, Circles, Wedges)
• JPEG images
• Optional Flate (deflate) compression for PDF streams
• Markdown to PDF conversion
• Multiple pages with custom sizes

Supported framework

This project targets .NET 10.

Installation

Install the package via the .NET CLI:

dotnet add package TinyPdf

Alternatively, you can add the TinyPdf.csproj to your solution and reference it from your project:

dotnet add reference ../src/TinyPdf/TinyPdf.csproj

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📄 Sample Outputs: Real Rendered PDF Previews

All sample documents below are generated programmatically using TinyPdf (pure C#, zero dependencies) in sub-millisecond execution times:

Automated Business Invoice (~320 Ops)	Multi-Section Analytics Report (~56 Ops)
Vector layout, dynamic line item tables, currency formatting, and totals (0.33 ms / doc)	Headings, structured grids, shaded backgrounds, and metric summaries (0.06 ms / doc)

Vector Wedge Pie Chart (~20 Ops)	POS Thermal Receipt (~18 Ops)
Precise mathematical arc and wedge vector slices with color fills (0.05 ms / doc)	Compact monospace thermal receipt layout with barcodes and itemization (0.04 ms / doc)

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Usage

Simple PDF

using TinyPdf;

var builder = TinyPdfCreate.Create();
// disable compression if you need uncompressed streams
// builder.Compress = false;

builder.Page(ctx => {
    ctx.Text("Hello World", 50, 700, 24);
    ctx.Rect(50, 650, 100, 20, "#FF0000");
});

byte[] pdf = builder.Build();
File.WriteAllBytes("output.pdf", pdf);

Markdown to PDF

using TinyPdf;

// disable compression via options
var options = new TinyPdfCreate.MarkdownOptions(Compress: false);
string md = "# Header\n\nThis is a paragraph.\n\n- List item";
byte[] pdf = TinyPdfCreate.Markdown(md, options);
File.WriteAllBytes("markdown.pdf", pdf);

Advanced Page Options

builder.Page(842, 595, ctx => { // A4 Landscape
    ctx.Line(0, 0, 842, 595, "#0000FF", 2);
});

Charts and Shapes

builder.Page(ctx => {
    // ctx.Circle(cx, cy, radius, fill, stroke, lineWidth)
    ctx.Circle(100, 700, 50, "#3498db");

    // ctx.Wedge(cx, cy, radius, startAngle, endAngle, fill, stroke, lineWidth)
    ctx.Wedge(300, 700, 50, 0, 90, "#e74c3c", "#000000", 2);
});

Clickable Links

builder.Page(ctx => {
    ctx.Text("Visit our website", 50, 700, 12);
    // Link(url, x, y, width, height, options)
    ctx.Link("https://github.com/ian-cowley/tinypdf-csharp", 50, 700, 100, 12, new TinyPdfCreate.LinkOptions(Underline: "#2563eb"));
});

Running tests

From the repository root run:

dotnet test

Benchmarks

To run the high-concurrency performance tests (1000 iterations per example):

dotnet run --project benchmarks/PerformanceTests/PerformanceTests.csproj

Alternatively, to run the BenchmarkDotNet suite:

dotnet run -p benchmarks/TinyPdf.Benchmarks

Performance Results

The following results were measured on AMD Ryzen AI 9 HX 370 generating 1,000 PDFs in parallel per document type with the PB-22 Zero-Copy PooledBufferWriter memory recycler:

Example	Iterations	Total Time (ms)	Avg Latency	Throughput	Complexity
Receipt	1,000	49.91 ms	0.0499 ms	20,036 PDFs/s	Methods: ~18
PieChart	1,000	57.26 ms	0.0573 ms	17,464 PDFs/s	Methods: ~20
Report	1,000	67.66 ms	0.0677 ms	14,780 PDFs/s	Methods: ~56
Resume	1,000	146.42 ms	0.1464 ms	6,830 PDFs/s	Markdown: ~100 lines
Letter	1,000	209.26 ms	0.2093 ms	4,778 PDFs/s	Markdown: ~60 lines
Invoice	1,000	336.82 ms	0.3368 ms	2,969 PDFs/s	Methods: ~320

Zero-Copy Memory Architecture (PB-22 Optimization)

Eliminates defensive byte array heap allocations during PDF binary generation via zero-copy PooledBufferWriter.GetMemory:

• Zero GC Pressure: Output buffers are recycled directly from the shared memory pool.
• 100% Native Pure C#: Zero unmanaged wrappers or native DLL dependencies.
• Test Suite: 18/18 rendering and serialization tests pass cleanly.

Publishing (Maintainers)

To release a new version to NuGet and GitHub:

1. Open PowerShell in the repository root.
2. Run: ./release.ps1
3. Follow the prompts for the commit message.

The script will automatically increment the patch version, commit, push, and create a GitHub tag, which triggers the CI/CD workflow.

Notes

This C# port preserves the core logic of the original TypeScript library (font width tables and PDF object serialization) so generated PDFs are compatible in structure. The library is intentionally small and dependency-free to keep it easy to embed in small projects.

By default output streams are compressed (FlateDecode) — set builder.Compress = false or pass new TinyPdfCreate.MarkdownOptions(Compress: false) to TinyPdfCreate.Markdown to disable compression.

Security: do not commit secrets or sensitive configuration to this repository. Use dotnet user-secrets or environment variables for local development.

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🆕 What's New in v0.1.11

• CRITICAL BUG FIX: SFNT 'head' table unitsPerEm at byte offset 18 — the previous implementation read from offset 36, producing incorrect font metrics for TrueType fonts.
• TrueType font metrics parser with full SFNT table directory navigation — correctly traverses the SFNT table directory to locate and parse any named table.
• AFM (Adobe Font Metrics) parser for Type1 font metrics — enables accurate character width lookup for Type1 PostScript fonts.
• 22 tests passing (100 %).

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Credits

Developed by Ian Cowley and Antigravity (Google DeepMind).