exiv2-wasm

> 🇰🇷 Read this in Korean: README.ko.md

Use Exiv2 in the browser via WebAssembly.
A tiny C++ wrapper (embind) exposes simple functions to read/write EXIF / IPTC / XMP.
Minimal deps are built for wasm (expat, brotli dec/common, inih); zlib comes from the Emscripten port.

---

Online Demo

- 한국어 버전
- English version

---

Project structure

``
exiv2-wasm/
├─ exiv2/ # submodule (Exiv2)
├─ libexpat/ # submodule (expat)
├─ brotli/ # submodule (google/brotli)
├─ inih/ # submodule (benhoyt/inih)
├─ scripts/
│ ├─ build.ps1 # Windows PowerShell build
│ └─ build.bash # Linux/macOS bash build
├─ wrapper.cpp # embind wrapper (read/write metadata)
├─ index.html # demo UI page
├─ dist/ # build outputs: exiv2.js / exiv2.wasm
└─ (build/, deps/) # build cache / installed deps (git-ignored)
`

Clone with submodules:
`bash
git clone --recurse-submodules https://github.com/gerosyab/exiv2-wasm.git
`

---

Prerequisites

$3

- CMake, Ninja
- Emscripten SDK (emcmake / emcc / em++ / emar)

Windows (PowerShell)
`powershell
winget install Kitware.CMake
winget install Ninja-build.Ninja
`

Linux (Debian/Ubuntu)
`bash
sudo apt update
sudo apt install -y cmake ninja-build python3
`

Emscripten SDK (all OS)
`bash

anywhere you like

git clone https://github.com/emscripten-core/emsdk.git
cd emsdk
./emsdk install latest
./emsdk activate latest

new shell(s):

source ./emsdk_env.sh # Linux/macOS

or on Windows PowerShell:

.\emsdk_env.ps1

`
> Re-run emsdk_env.sh / emsdk_env.ps1 in each new shell.

---

Build

Windows (PowerShell)
`powershell
cd exiv2-wasm

one-session policy (optional)

Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass

clean build

.\scripts\build.ps1 -Clean

incremental build

.\scripts\build.ps1
`

Linux/macOS (bash/zsh)
`bash
cd exiv2-wasm
chmod +x scripts/build.bash

clean build

./scripts/build.bash -c

incremental build

./scripts/build.bash
`

Outputs: dist/exiv2.js and dist/exiv2.wasm

---

Run the demo

`bash

from project root

python -m http.server 8080

open:

http://localhost:8080/index.html

`

---

JavaScript usage

Wrapper API:

- read(u8: Uint8Array) -> { exif: Object, iptc: Object, xmp: Object }
- readTagText(u8, key: string) -> string | null
- readTagBytes(u8, key: string) -> Uint8Array | null
- writeString(u8, key: string, value: string) -> Uint8Array (returns new buffer)
- writeBytes(u8, key: string, data: Uint8Array) -> Uint8Array

Browser (CDN +


`

Browser (CDN + ESM import)
`js


`

ESM (Node.js / Vite / webpack / Rollup)
`
import { createExiv2Module } from 'exiv2-wasm';

const exiv2 = await createExiv2Module();

const fs = await import('fs/promises');
const u8 = new Uint8Array(await fs.readFile('image.jpg'));
const meta = exiv2.read(u8);
console.log('Model:', meta.exif['Exif.Image.Model']);
`

CommonJS
`js
const { createExiv2Module } = require('exiv2-wasm');
const fs = require('fs');

function fileToU8(path) {
return new Uint8Array(fs.readFileSync(path));
}

createExiv2Module().then((exiv2) => {
const u8 = fileToU8('image.jpg');
const meta = exiv2.read(u8);
console.log('Model:', meta.exif['Exif.Image.Model']);
});
`

Common keys (examples)
- Camera: Exif.Image.Make, Exif.Image.Model
- Exposure: Exif.Photo.ExposureTime, Exif.Photo.ShutterSpeedValue
- Aperture: Exif.Photo.FNumber, Exif.Photo.ApertureValue
- ISO: Exif.Photo.PhotographicSensitivity (or Exif.Photo.ISOSpeedRatings)
- Title/Author/Comment:
- XMP: Xmp.dc.title, Xmp.dc.creator, Xmp.dc.description
- EXIF: Exif.Image.ImageDescription, Exif.Image.Artist, Exif.Photo.UserComment
- Windows XP* Unicode: Exif.Image.XPTitle, Exif.Image.XPAuthor, Exif.Image.XPComment (UTF-16LE)

---

Notes

- Exiv2 CLI build is disabled: -DEXIV2_BUILD_EXIV2_COMMAND=OFF
- BMFF/HEIF support enabled: -DEXIV2_ENABLE_BMFF=ON
- If submodules show empty after clone:
git submodule update --init --recursive`