Getting nghttp2.dll on Windows

Delphi-nghttp2 loads nghttp2.dll at startup via SafeLoadLibrary — the DLL must be findable by Windows's standard loader search order (.exe directory first, then PATH).

Three options, from easiest to most involved:

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Option A — Prebuilt from curl for Windows (recommended)

No compiler or toolchain needed. The curl for Windows project bundles nghttp2.dll alongside curl.exe.

1. Go to https://curl.se/windows/

2. Download the package that matches your Delphi target platform:

   Delphi target	Package to download
   Win64 (dcc64, Project → Target platforms → Windows 64-bit)	Win64 package
   Win32 (dcc32, Project → Target platforms → Windows 32-bit)	Win32 package

   The filename looks like curl-X.YY.Z_A-winNN-mingw.zip.

3. Extract the zip and open the bin\ subfolder.

4. Copy nghttp2.dll next to your compiled .exe.

Bitness must match. A Win64 executable loading a Win32 DLL (or vice versa) fails immediately with error 0xc000007b. Verify with:

dumpbin /headers nghttp2.dll | findstr machine

14C = Win32 (x86) · 8664 = Win64 (x64)

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Option B — vcpkg

Requires vcpkg bootstrapped and the Desktop development with C++ workload installed in Visual Studio or the Visual Studio Build Tools.

vcpkg install nghttp2:x64-windows   :: Win64 (most common)
vcpkg install nghttp2:x86-windows   :: Win32

The DLL lands in <vcpkg-root>\installed\<triplet>\bin\nghttp2.dll. Copy it next to your .exe, or add that bin\ folder to PATH.

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Option C — Build from source (MSVC + CMake)

Use this if you need a specific version, debug symbols, or the import library (.lib).

Prerequisites: Visual Studio with the Desktop development with C++ workload, CMake ≥ 3.25, Git.

Visual Studio Community is free for individual developers: https://visualstudio.microsoft.com/downloads/ During installation select the Desktop development with C++ workload. CMake: https://cmake.org/download/ — tick "Add CMake to the system PATH" during install.

Win64

git clone https://github.com/nghttp2/nghttp2.git
cd nghttp2

cmake -S . -B build64 -G "Visual Studio 17 2022" -A x64 ^
  -DENABLE_LIB_ONLY=ON  ^
  -DENABLE_SHARED=ON    ^
  -DENABLE_STATIC=OFF   ^
  -DENABLE_EXAMPLES=OFF ^
  -DENABLE_APP=OFF      ^
  -DENABLE_TESTS=OFF

cmake --build build64 --config Release --target nghttp2

Find the output:

dir /s /b build64\nghttp2.dll

You do not need the "x64 Native Tools Command Prompt". The Visual Studio generator with -A x64 targets 64-bit on its own, from an ordinary prompt or from VS Code's terminal. The Developer Command Prompt is only worth opening when you need MSVC environment variables available to other commands in the same session.

Do not mix MSVC and MinGW. Build nghttp2 with the same toolchain family as the application that will load it: MSVC for a Delphi or Visual Studio binary, MinGW/MSYS2 only if you specifically need a MinGW DLL. A mismatch links and loads, then fails in ways that look like corruption rather than a toolchain problem.

Win32 (32-bit)

cmake -S . -B build32 -G "Visual Studio 17 2022" -A Win32 ^
  -DENABLE_LIB_ONLY=ON  ^
  -DENABLE_SHARED=ON    ^
  -DENABLE_STATIC=OFF   ^
  -DENABLE_EXAMPLES=OFF ^
  -DENABLE_APP=OFF      ^
  -DENABLE_TESTS=OFF

cmake --build build32 --config Release --target nghttp2
dir /s /b build32\nghttp2.dll

Visual Studio version: replace "Visual Studio 17 2022" with the generator matching your installed toolchain ("Visual Studio 16 2019", "Visual Studio 15 2017", …). Run cmake --help for the full list.

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Where to place the DLL

Scenario	Placement
Run from Delphi IDE (F9)	Same folder as the .exe output (usually Win32\Debug\ or Win64\Release\)
Deployed .exe	Same folder as the .exe
Multiple .exes sharing one copy	Any folder on the system or user PATH

The .exe directory is always searched first — no registry or PATH change required.

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Verify the DLL loads

if not NghttpLoad then
  raise Exception.Create(NghttpLoadError);
// or just call TNghttp2Server.Start — it calls NghttpLoad automatically

NghttpLoadError returns the DLL names tried and the OS error, so the message tells you exactly what went wrong.

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Also needed: OpenSSL DLLs (TLS mode only)

TTlsServerContext / TTlsClientContext load libssl-3-x64.dll and libcrypto-3-x64.dll (OpenSSL 3.x) or their 1.1.x equivalents. Place those next to the .exe as well.

Prebuilt OpenSSL binaries for Windows:

• https://slproweb.com/products/Win32OpenSSL.html (full installer)
• The same curl for Windows bundle — bin\libssl-3-x64.dll and bin\libcrypto-3-x64.dll are included in the Win64 package alongside nghttp2.dll.

For h2c (cleartext) operation only nghttp2.dll is required.