Free · No telemetry · v1.0.0

Compare anything.
Merge with confidence.

A fast, free diff and 3-way merge tool for Windows. Text, folders and binaries, built to slot straight into TortoiseGit and git.

Download for Windows Quick start

v1.0.0 150.7 MB Windows 10/11 x64 Portable zip

eMass Compare text diff: two versions of decoder.js side by side, changed words highlighted in red and green, with a differences overview on the right

785automated tests

20,000+fuzz cases

200kline files, virtualized

100 MB+binaries in hex view

0telemetry, accounts, ads

Four tools, one window

Every kind of compare you reach for

Text, 3-way merge, folders and raw bytes. The right view opens automatically for what you give it.

Side-by-side text diff

Line and word-level highlighting shows exactly what changed, not just which lines moved.

Ignore whitespace, case and blank lines
Copy blocks across, edit in place and save
Keeps encoding (UTF-8, UTF-16, BOM) and line endings
Virtualized rendering stays smooth on 200k-line files

Text diff of decoder.js with word-level changes highlighted

Text diff of decoder.js in the light theme

3-way merge that git can trust

Mine, Base and Theirs side by side above an editable output. Non-conflicting changes merge themselves.

Per conflict: take mine, theirs, both or base
Edit the result directly, with undo and redo
Auto-merge of non-conflicting changes
Exit code 0 / 1 that TortoiseGit and git mergetool trust

3-way merge of uart.c: Mine, Base and Theirs panes above the merged output, with two unresolved conflicts and per-conflict buttons

3-way merge of uart.c in the light theme

Recursive folder compare

See what was added, removed or changed across two whole trees, then open any pair with a double-click.

Compare by content, size or date
Exclude globs such as .git; node_modules; *.o
Filter to all, differences, same or orphans
Works with git difftool -d

Folder compare of release-2.3 and release-2.4: changed, left-only and right-only files marked

Folder compare of two release folders in the light theme

Hex compare for big binaries

Firmware images, archives and build outputs. Files are streamed, so 100 MB+ opens without a stall.

Byte-level differences in hex and ASCII
Go to any offset (0x1F0 or 496)
Jump between differences with F7
Binary files are detected automatically

Hex compare of two firmware images with differing bytes highlighted in both hex and ASCII columns

Hex compare of two firmware images in the light theme

Built for daily use

The details that make it dependable

A drop-in replacement

Understands TortoiseGit and Beyond Compare command-line syntax, so existing configs and scripts keep working.

/base:/mine:/theirs:/merged:/title1:/leftreadonly

Saves what it read

UTF-8, UTF-16 and BOM preserved. CRLF stays CRLF. No surprise whole-file diffs after a save.

Fast on huge files

Virtualized rendering for 200k-line files, and streamed hex compare for 100 MB+ binaries.

Headless CLI for CI

Unified diff output, merges with conflict markers, and exit codes 0, 1 and 2 for scripts.

Dark & light themes

Carefully tuned diff colours in both themes, switchable with one click.

Keyboard-driven

Move between differences, copy blocks and save without touching the mouse.

F7 / Shift+F7 next / previous Alt+→ copy block right Ctrl+S save

Private by default

No telemetry, no account, no network needed. Nothing phones home, so your code stays on your machine.

No telemetryWorks offlineNo accountNo cookies on this site

TortoiseGit & git

Plugs into the workflow you already have

Right-click › TortoiseGit › Diff opens eMass Compare. Conflicts open the 3-way merge. When you save with every conflict resolved it exits with 0, so the file is marked resolved, and never before.

One-command TortoiseGit setup that backs up and restores your previous diff tool
git difftool and git mergetool config included
Diff output byte-identical to git diff; merge output identical to git merge-file in cross-checks

PowerShell · from the source repo

powershell -ExecutionPolicy Bypass -File scripts\integration\install-tortoisegit.ps1 -GitConfig

~/.gitconfig

[diff]
    tool = emass
[merge]
    tool = emass
[difftool "emass"]
    cmd = \"C:/path/EmassCompare.exe\" \"$LOCAL\" \"$REMOTE\" --left-readonly
[mergetool "emass"]
    cmd = \"C:/path/EmassCompare.exe\" --merge --base \"$BASE\" --mine \"$LOCAL\" --theirs \"$REMOTE\" --output \"$MERGED\"
    trustExitCode = true

Quick start

Up and running in about a minute

No installer, no admin rights. Unzip it anywhere and point TortoiseGit at it.

Download & unzip

Extract EmassCompare-1.0.0-win-x64.zip to a folder such as C:\Tools\EmassCompare and run EmassCompare.exe once.
Download zip
Point TortoiseGit at it

TortoiseGit › Settings › Diff Viewer: set both the diff viewer and the Merge Tool to External with the command lines below.

From the source repo, install-tortoisegit.ps1 does it for you and backs up your previous tools.
Right-click › Diff

Right-click a modified file › TortoiseGit › Diff. On a conflict, Edit conflicts opens the 3-way merge.

TortoiseGit external tool settings

Replace C:\path with the folder you unzipped to. TortoiseGit adds the quotes around each %placeholder itself.

Diff Viewer › External

"C:\path\EmassCompare.exe" %base %mine /title1=%bname /title2=%yname /leftreadonly

Merge Tool › External

"C:\path\EmassCompare.exe" /base:%base /mine:%mine /theirs:%theirs /merged:%merged /basename:%bname /minename:%yname /theirsname:%tname /mergedname:%mname

Command line

Headless mode for scripts & CI

The same diff and merge engines, without a window. Results go to a file or pipe and the exit code tells your script what happened.

0: Identical, or merged cleanly
1: Different, or conflicts left (written with markers)
2: Error. For a merge, nothing is written

EmassCompare.exe is a GUI program: redirect its output to a file or pipe it. Exit codes work everywhere.

Examples

# Unified diff, same format as git diff
EmassCompare.exe --headless old\app.js new\app.js > changes.diff

# Ignore all whitespace (-w), case (-i) and blank lines (-B)
EmassCompare.exe --headless -w -i -B a.txt b.txt > changes.diff

# 3-way merge; conflicts are written with markers (exit 1)
EmassCompare.exe --headless --merge --base base.c --mine mine.c --theirs theirs.c -o merged.c

# Add the ||||||| base section to conflict markers
EmassCompare.exe --headless --merge --diff3 base.c mine.c theirs.c -o merged.c

# Folder compare by content, skipping build output
EmassCompare.exe --headless --folder --exclude node_modules --exclude "*.o" v2.3 v2.4 > tree.txt

# Beyond Compare positional merge order also works
EmassCompare.exe mine.c theirs.c base.c merged.c

Correctness first

Tested like it matters, because merges do

A diff tool you can't trust is worse than none. Every release is checked against git itself.

785

Automated tests

Diff, merge, encodings, folder scans, CLI parsing and the TortoiseGit integration scripts.

20,000+

Fuzz cases

Randomised inputs hammer the diff and merge engines looking for crashes and wrong output.

= git

Cross-checked against git

Diff output byte-identical to git diff, merge output identical to git merge-file.

How it stacks up

An honest comparison

Against what you typically get from free diff tools. Where we are behind, we say so.

Feature	eMass Compare	Typical free diff tools
Side-by-side diff with word-level highlighting		Common
3-way merge with editable output		Varies
Per-conflict mine / theirs / both / base, auto-merge		Varies
Exit codes TortoiseGit and git mergetool can trust		Varies
Accepts TortoiseGit & Beyond Compare switches		Rare
Streaming hex compare of 100 MB+ files		Rare
Recursive folder compare with exclude globs		Varies
Preserves encoding, BOM and line endings on save		Varies
Headless CLI (unified diff, merge, exit codes)		Varies
Dark and light themes		Varies
No telemetry, works offline, no account		Varies
Syntax highlighting	Planned	Common
Installer	Portable zip	Common
Price	Free	Free

Roadmap

Coming next

Planned, not promised dates. Version 1.0 focuses on getting compare and merge right.

Syntax highlighting
Find & replace
Tabs
Explorer context menu
Installer

FAQ

Questions, answered

Is it really free?

Yes. No trial period, no licence key, no account and no nag screens.

Windows says “Windows protected your PC”. Is that normal?

Yes. EmassCompare.exe is not code-signed yet, so Microsoft Defender SmartScreen warns about it. Click More info › Run anyway. If you want to be sure the file is the one we published, check its SHA-256 first (next question).

How do I verify the download?

Run this in PowerShell in the folder you downloaded to:

PowerShell

Get-FileHash .\EmassCompare-1.0.0-win-x64.zip -Algorithm SHA256

The hash should be:

SHA-256

5d39b13ba87952b1acbf3cc5448e51f5314ce8d26c08519882118542c98600bb

Does the app collect any data?

No. There is no telemetry, no account and it works fully offline. (This website counts page views and downloads anonymously, without cookies, so we know whether anyone is using it.)

Can it replace Beyond Compare in my existing configs and scripts?

For diff and merge, usually yes. It accepts the TortoiseGit and Beyond Compare switches (/base: /mine: /theirs: /merged: /title1:, read-only flags) and Beyond Compare's four-argument merge order mine theirs base merged. Change the exe path and keep the rest.

How does git know a merge is finished?

The merge window exits with 0 only after you save with no conflicts left, and with 1 if you cancel or leave conflicts. Set mergetool.emass.trustExitCode = true so git relies on that instead of just checking whether the file changed.

What are the system requirements?

Windows 10 or 11, 64-bit (x64). It is a portable zip of about 150.7 MB: unzip it and run EmassCompare.exe. No installer and no admin rights needed.

How do I uninstall it?

Delete the folder. If you set it up in TortoiseGit by hand, switch the Diff Viewer and Merge Tool back. If you used install-tortoisegit.ps1, run uninstall-tortoisegit.ps1 to restore your previous tools.

Make your next merge the easy one.

Free, portable and private. Ready in about a minute.

Download v1.0.0

150.7 MBWindows 10/11 x64No installer

Compare anything.Merge with confidence.