Delta Patcher
Download

Delta Patcher Guide & Download

Delta Patcher: Download, Install & Use XDelta Patches

Delta Patcher is a free, open-source desktop app for applying and creating XDelta patches. Choose your original file and a .xdelta patch, click Apply patch, and it rebuilds the modified file, with no command line and nothing else to install. This independent guide walks you through each step, from choosing the right download to fixing checksum errors.

Download Delta Patcher How to Use Delta Patcher
  • XDelta (VCDIFF) patches
  • Apply & create
  • Windows · macOS · Linux
  • Free · GPL-2.0

Illustration of Delta Patcher 3.1.6 with “Backup original file” enabled. Field names match the real program.

Delta Patcher download

Official builds from the developer’s GitHub releases: portable .zip files with no installer and nothing bundled.

Latest version
3.1.6
Released
License
Free · GPL-2.0
Package
Portable .zip
Download Delta Patcher View Release Information

Always verify the required source file and patch version before applying a patch. The 32-bit Windows build and SHA-256 checksums are on the download page, and is Delta Patcher safe? explains the first-launch warnings.

The basics

What is Delta Patcher?

Delta Patcher, often written as one word (deltapatcher), is a graphical XDelta patcher: a program for applying and creating delta patches without touching the command line. It’s developed by Marco Calautti and released as open source under the GPL-2.0 license. It does two jobs: applying a patch to a file you already have, and creating a patch that records the differences between two versions of a file.

An XDelta patch doesn’t contain a complete file. It holds instructions such as “copy this range of bytes from the original” and “add these new bytes here.” That’s why patches are usually small, and why each one only works with the exact original file it was made from.

Many XDelta tools are front-ends that run the separate xdelta3 command-line program. Delta Patcher builds the xdelta3 engine into the app instead, so it works on its own.

XDelta patch: a .xdelta file in the VCDIFF format, also called a delta patch, that describes how to turn one file into another.
Original (source) file: the unmodified file the patch was built from. It has to match byte for byte.
Patched (output) file: the result, which is the original with the patch’s changes applied.
Who uses it: translators, modders and developers who share changes without redistributing whole files, and the people who apply those changes to their own copies.
Learn how Delta Patcher works What is XDelta?
Original file Game (USA).iso
XDelta patch patch.xdelta
Patched file your modified copy
The original file plus the patch rebuilds the modified file.
Developer
Marco Calautti
Latest version
3.1.6 (August 18, 2025)
License
GNU General Public License v2.0
Patch format
.xdelta (VCDIFF, as produced by xdelta3)
Engine
xdelta3 3.1.0, built in

Features

What Delta Patcher can do

Everything below is in the current release. None of it needs plugins, extra downloads or the command line.

  • XDelta patch support

    Reads and writes the VCDIFF format used by xdelta3, including patches that use lzma, djw or fgk secondary compression.

  • Apply existing patches

    Pick the original file and the patch, then click Apply patch. You can replace the original or keep it and write a separate patched copy.

  • Create XDelta patches

    Compare an original file with your modified version and save the differences as a .xdelta file, with an optional description for users.

  • Simple interface

    Two fields and one button for applying, four for creating. Drag and drop works too, so you rarely need a file dialog.

  • Checksum validation

    On by default. xdelta3 checks each block of output as it’s rebuilt, so a wrong source file stops the patch instead of producing a broken file.

  • Self-contained engine

    The xdelta3 3.1.0 library is built in. There’s no separate xdelta3 install, no runtime to add, and no installer to run.

  • Cross-platform builds

    Native builds for Windows 7 or later (64-bit and 32-bit), macOS 11 or later on Apple silicon and Intel, and Linux through GTK 3 or Flathub.

  • Patch creation options

    Set the compression level (0–9), secondary compression, source window size and whether checksums are written into the patch.

Explore every Delta Patcher feature in depth

Use cases

What people use Delta Patcher for

Delta Patcher works on any file, byte by byte. It doesn’t know or care whether the file is a disc image, a document or a program. Some uses below are general capabilities; others are simply common in communities that share patches.

Capability something the software is built to doCommunity use a popular way people use it

  • Community use

    Fan translations

    Translation groups publish a small patch instead of a full translated game. Players apply it to their own copy of the original release.

  • Community use

    ROM hacks and mods

    Level edits, bug fixes and restorations are often shared as XDelta patches, especially for DS and disc-based games, where changes move data around inside the file.

  • Capability

    Large disc images

    XDelta handles CD and DVD images and other large files. Since version 3.1.5, Delta Patcher also works with files larger than 4 GB.

  • Capability

    Binary patch distribution

    Ship an update as the difference between two versions of any file, so people download only what changed rather than the whole file again.

  • Capability

    Developer build diffs

    Create a patch between two builds of a data file or asset, and use the description field to tell users exactly which file it applies to.

  • Capability

    Testing modified files

    Keep one untouched original and rebuild the modified version whenever you need it, from the original plus a patch that’s a fraction of the size.

How it works

How delta patching works

Applying a patch takes five steps. Select a step to see what’s happening and why it matters.

  1. Choose the original fileThe unmodified file the patch was made for.

    Why it matters: the patch refers to exact byte positions in this file. A different revision, region or dump won’t line up, and the checksums inside the patch will stop the process.

  2. Choose the .xdelta patchThe patch file you downloaded from its author.

    If the author included a description, Delta Patcher shows it in a Patch info tooltip as soon as the patch loads. Read it: it often names the exact source file you need.

  3. Decide how the output is savedReplace the original, or keep it and write a new file.

    There’s no output picker. The result goes next to the original. With Backup original file ticked, your original stays and the result is saved as namePATCHED.ext. Otherwise, a successful patch replaces the original.

  4. Apply the patchClick Apply patch and wait for the confirmation.

    xdelta3 rebuilds the new file window by window and checks each window against the checksum stored in the patch. On a mismatch it stops and tells you the file you’re trying to patch isn’t the right one.

  5. Test the resultOpen the patched file in the program that uses it.

    If the patch author published a checksum for the finished file, compare it with yours. A match confirms the patch was applied exactly as intended.

Original fileGame (USA).iso Ready
XDelta patchtranslation-v1.2.xdelta Ready
OutputGame (USA)PATCHED.iso Ready
Apply patchchecksum validation: on Ready
Patched fileready to test Ready

Original file + XDelta patch → patched file. Delta Patcher checks every window of output as it rebuilds the file.

See the Complete Delta Patcher Guide Go deeper: how XDelta patches work

Installation

Install Delta Patcher on Windows, macOS or Linux

Delta Patcher is a portable app: download a .zip, extract it and run the program. There’s no setup wizard, and removing it is as simple as deleting the file.

  • Windows

    Windows 7 or later · 64-bit & 32-bit

    1. Download the 64-bit .zip (or the 32-bit build for 32-bit Windows).
    2. Right-click the .zip and choose Extract All.
    3. Open the folder and run DeltaPatcher.exe.

    The program isn’t code-signed, so SmartScreen may warn you the first time. Continue only if the file came from the official release.

  • macOS

    macOS 11 Big Sur or later · Apple silicon & Intel

    1. Download the macOS universal .zip.
    2. Open it to get DeltaPatcher.app, then move the app to Applications.
    3. Open the app. If macOS blocks it, allow it under Privacy & Security.

    The app is distributed outside the App Store, so macOS may ask you to approve it on first launch.

  • Linux

    Flathub (x86-64, ARM64) or GTK 3 .zip (x86-64)

    1. Install it from Flathub, or download the GTK 3 .zip.
    2. For the .zip: extract it and make DeltaPatcher executable.
    3. Launch it from your app menu or with ./DeltaPatcher.

    The .zip build needs glibc 2.38 or newer. On older distributions, use the Flathub package.

Read the full installation guide

Quick start

How to use Delta Patcher

Here’s the short version of applying an XDelta patch. The full guide explains every option and what to do if something fails.

  1. Download Delta Patcher

    Get the official build for your system from the download page.

  2. Launch the program

    It opens in patch application mode, with Original file and XDelta patch fields.

  3. Select the original file

    Click the folder button next to Original file, or drag the file onto the window.

  4. Select the .xdelta patch

    Click the folder button next to XDelta patch. If a Patch info tooltip appears, read it.

  5. Choose whether to keep the original

    Open the options menu next to Apply patch and tick Backup original file to keep it. It’s off by default.

  6. Apply the patch

    Click Apply patch and wait for “Patch successfully applied!”

  7. Verify the result

    Test the patched file, and compare its checksum if the author published one.

Delta Patcher 3.1.6 running on Windows in patch application mode, with an original file and a .xdelta patch selected above the Apply patch button
The whole program: two fields and a button. This is Delta Patcher 3.1.6 on Windows.
Read the Full Step-by-Step Guide

Patch creation

Create an XDelta patch

Switch Delta Patcher to patch creation mode and it compares two files: the untouched original and your modified version. The differences are written to a .xdelta file you can share. Anyone who uses the patch needs their own copy of the same original.

  • Add an optional description that Delta Patcher users see when they load the patch.
  • Tune the compression level, secondary compression and source window size.
  • Keep Add Checksum to patch on so a wrong source file is caught instead of producing a broken result.
Learn how to create an XDelta patch
ORIGINAL FILEGame (USA).iso
MODIFIED FILEGame (USA) [translated].iso
.XDELTA PATCHtranslation-v1.2.xdelta

Troubleshooting

Common Delta Patcher errors

Most failed patches come down to one thing: the original file isn’t the exact one the patch expects. These are the messages people see most often.

Troubleshoot every common XDelta error

Guides

Guides for every step

Background reading for when you want to understand what’s happening, not just which button to click.

Browse all guides

FAQ

Delta Patcher questions, answered

Is Delta Patcher free?

Yes. Delta Patcher is free, open-source software released under the GNU General Public License v2.0. Its source code is public on GitHub (opens external site).

Do I need to install xdelta3 separately?

No. The xdelta3 engine is built into Delta Patcher (version 3.1.6 includes xdelta3 3.1.0), so the program works on its own.

Does Delta Patcher work on Windows, macOS and Linux?

Yes. There are builds for Windows 7 or later (64-bit and 32-bit), macOS 11 Big Sur or later on Apple silicon and Intel, and Linux through a GTK 3 build or Flathub. See the installation guide for each system.

Where does Delta Patcher save the patched file?

In the same folder as the original file. By default it replaces the original. If you tick Backup original file, the original is kept and the result is saved with PATCHED added to its name. More on where the output goes.

Why does my patch fail with a checksum error?

Your original file isn’t the exact file the patch was made from. Check the patch’s readme for the required version and checksum, then compare it with your file.

See all Delta Patcher FAQs

Ready to apply your patch?

Download the official Delta Patcher build for your system, then follow the step-by-step guide. If anything goes wrong, the troubleshooting guide covers every common error.

Download Delta Patcher How to Use Delta Patcher